Vitamin B3
Uses
The body uses the water-soluble vitamin B3 in the process of releasing energy from carbohydrates. It is needed to form fat from carbohydrates and to process alcohol. The niacin form of vitamin B3 also regulates cholesterol, though niacinamide does not.
Our proprietary “Star-Rating” system was developed to help you easily understand the amount of scientific support behind each supplement in relation to a specific health condition. While there is no way to predict whether a vitamin, mineral, or herb will successfully treat or prevent associated health conditions, our unique ratings tell you how well these supplements are understood by the medical community, and whether studies have found them to be effective for other people.
For over a decade, our team has combed through thousands of research articles published in reputable journals. To help you make educated decisions, and to better understand controversial or confusing supplements, our medical experts have digested the science into these three easy-to-follow ratings. We hope this provides you with a helpful resource to make informed decisions towards your health and well-being.
3 Stars Reliable and relatively consistent scientific data showing a substantial health benefit.
2 Stars Contradictory, insufficient, or preliminary studies suggesting a health benefit or minimal health benefit.
1 Star For an herb, supported by traditional use but minimal or no scientific evidence. For a supplement, little scientific support.
This supplement has been used in connection with the following health conditions:
| Used for | Why |
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3 Stars
Acne Vulgaris
Apply 4% gel twice per day
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In a double-blind trial, applying a topical 4% niacinamide gel twice daily for two months significantly improved acne.
In a double-blind trial, topical application of a 4% gel twice daily for two months resulted in significant in improvement in people with acne. However, there is little reason to believe this vitamin would have similar actions if taken orally.
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3 Stars
High Triglycerides
500 mg three times per day
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The niacin form of vitamin B3 is used by some doctors to lower triglycerides, however, the quantity needed to achieve reductions may cause side effects. Ask your doctor is niacin is right for you.
The form of vitamin B3 is used by doctors to lower cholesterol levels, but niacin also lowers TG levels. The amount of niacin needed to achieve worthwhile reductions in cholesterol and TG levels is several grams per day. Such quantities can cause side effects, including potential damage to the liver, and should not be taken without the supervision of a doctor. Some doctors recommend (a special form of vitamin B3) as an alternative to niacin. A typical amount recommended is 500 mg three times per day. This form of vitamin B3 does not typically cause a skin flush and is said to be safer for the liver than niacin. However, the alleged safety advantage of inositol hexaniacinate needs to be confirmed by additional clinical trials. Moreover, it is not clear whether inositol hexaniacinate is as effective as niacin at lowering cholesterol and TG levels. |
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3 Stars
Intermittent Claudication
2 grams twice per day
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Inositol hexaniacinate, a special form of vitamin B3, has been used successfully to reduce symptoms, this treatment should be monitored by a doctor.
(IHN), a special form of vitamin B3, has been used successfully to treat intermittent claudication. The alleged advantage of IHN over niacin (another form of vitamin B3) is a lower risk of toxicity. A double-blind trial explored the effect of 2 grams of IHN taken twice per day for three months. In nonsmokers and in people with unchanged smoking habits, the increase in walking distance was significantly greater in the IHN group than in the placebo group. Other double-blind research has confirmed IHN’s ability to improve symptoms of intermittent claudication compared with placebo. This treatment should be monitored by a doctor. |
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3 Stars
Osteoarthritis
Refer to label instructions
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Supplemental niacinamide (a form of vitamin B3) has been reported to increase joint mobility, improve muscle strength, and decrease fatigue in people with osteoarthritis.
In the 1940s and 1950s, one doctor reported that supplemental (a form of vitamin B3) increased joint mobility, improved muscle strength, and decreased fatigue in people with osteoarthritis. In the 1990s, a double-blind trial confirmed a reduction in symptoms from niacinamide within 12 weeks of beginning supplementation. Although amounts used have varied from trial to trial, many doctors recommend 250 to 500 mg of niacinamide four or more times per day (with the higher amounts reserved for people with more advanced arthritis). The mechanism by which niacinamide reduces symptoms is not known. |
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2 Stars
Atherosclerosis
2,000 mg per day (only under a doctor's supervision)
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In a preliminary trial, doctor-supervised supplementation with extended-release niacin in combination with a cholesterol-lowering statin drug appeared to reverse atherosclerosis of the carotid arteries (the arteries that supply blood to the brain).
Niacin is known to reduce serum cholesterol levels and to increase levels of HDL ("good") cholesterol. In a preliminary trial, supplementation with extended-release niacin, when used in combination with a cholesterol-lowering statin drug, appeared to reverse atherosclerosis of the carotid arteries (the arteries that supply blood to the brain). The combination of a statin drug and niacin was significantly more effective than a statin drug combined with a second cholesterol-lowering drug (ezetimibe). In addition, the statin-niacin combination was associated with a significant reduction in the number of major cardiovascular event (such as myocardial infarction or death from coronary heart disease). Niacin was used in this study in amounts up to 2,000 mg per day. These large amounts of niacin have the potential to cause side effects, including liver damage, and should be taken only with the supervision of a doctor.
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2 Stars
Dysmenorrhea
200 mg daily throughout menstrual cycle; for cramps: 100 mg every two to three hours
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The niacin form of vitamin B3 has been reported to be effective in relieving menstrual cramps in 87% of a group of women supplementing with it throughout the menstrual cycle.
The niacin form of has been reported to be effective in relieving menstrual cramps in 87% of a group of women taking 200 mg of niacin per day throughout the menstrual cycle. They then took 100 mg every two or three hours while experiencing menstrual cramps. In a follow-up study, this protocol was combined with 300 mg of vitamin C and 60 mg of the flavonoid rutin per day, which resulted in a 90% effectiveness for relieving menstrual cramps. Since these two preliminary studies were published many years ago, no further research has explored the relationship between niacin and dysmenorrhea. Niacin may not be effective unless taken for seven to ten days before the onset of menstrual flow. |
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2 Stars
Dysmenorrhea (Rutin, Vitamin C)
200 mg niacin daily, 300 mg vitamin C daily, and 60 mg rutin daily througout menstrual cycle; for cramps: 100 mg niacin every two to three hours
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Supplementing with a combination of vitamin B3, vitamin C, and the flavonoid rutin resulted in a 90% effectiveness for relieving menstrual cramps in one study.
The niacin form of vitamin B3 has been reported to be effective in relieving menstrual cramps in 87% of a group of women taking 200 mg of niacin per day throughout the menstrual cycle. They then took 100 mg every two or three hours while experiencing menstrual cramps. In a follow-up study, this protocol was combined with 300 mg of vitamin C and 60 mg of the flavonoid rutin per day, which resulted in a 90% effectiveness for relieving menstrual cramps. Since these two preliminary studies were published many years ago, no further research has explored the relationship between niacin and dysmenorrhea. Niacin may not be effective unless taken for seven to ten days before the onset of menstrual flow.
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2 Stars
High Triglycerides
500 mg three times per day
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Some doctors recommend inositol hexaniacinate (a special form of vitamin B3) as an alternative to niacin, which can have negative side effects.
The niacin form of vitamin B3 is used by doctors to lower cholesterol levels, but niacin also lowers TG levels. The amount of niacin needed to achieve worthwhile reductions in cholesterol and TG levels is several grams per day. Such quantities can cause side effects, including potential damage to the liver, and should not be taken without supervision of a doctor. Some doctors recommend inositol hexaniacinate (a special for of vitamin B3) as an alternative to niacin. A typical amount recommended is 500 mg three times per day. This form of vitamin B3 does not typically cause a skin flush and is said to be safer for the liver than niacin. However, the alleged safety advantage of inositol hexaniacinate needs to be confirmed by addition clinical trials. Moreover, it is not clear whether inositol hexaniacinate is as effective as niacin at lowering cholesterol and TG levels.
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2 Stars
Peripheral Vascular Disease
1,200 mg a day of inositol hexaniacinate
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Vitamin B3 may help prevent and treat skin ulcers caused by peripheral vascular disease.
One controlled study compared a type of niacin (vitamin B3) known as to the drug pyridinolcarbamate for the treatment of skin ulcers caused by PVD. A placebo was not included in this trial, and both 1.2 grams daily of inositol hexaniacinate and 1.5 grams daily of the drug produced beneficial results in about half of the patients. |
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2 Stars
Raynaud’s Disease
3 to 4 grams daily of inositol hexaniacinate
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A variation on the B vitamin niacin, inositol hexaniacinate has been shown to reduce arterial spasm and improve peripheral circulation.
has been used with some success for relieving symptoms of Raynaud’s disease. In one study, 30 people with Raynaud’s disease taking 4 grams of inositol hexaniacinate each day for three months showed less spasm of their arteries. Another study, involving six people taking 3 grams per day of inositol hexaniacinate, again showed that this supplement improved peripheral circulation. People taking this supplement in these amounts should be under the care of a doctor.
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2 Stars
Schizophrenia
Consult a qualified healthcare practitioner
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High amounts of vitamin B3 may create a more optimal biochemical environment and increase recovery rate and reduce hospitalization and suicide rates.
The term “orthomolecular psychiatry” was coined by Linus Pauling in 1968 to refer to the treatment of psychiatric illnesses with substances (such as vitamins) that are normally present in the body. In orthomolecular psychiatry, high amounts of vitamins are sometimes used, not to correct a deficiency per se, but to create a more optimal biochemical environment. The mainstay of the orthomolecular approach to schizophrenia is or () in high amounts. In early double-blind trials, 3 grams of niacin daily resulted in a doubling of the recovery rate, a 50% reduction in hospitalization rates, and a dramatic reduction in suicide rates. In a preliminary trial, some schizophrenic patients continued a course of vitamins (4 to 10 grams of niacin or niacinamide, 4 grams of vitamin C, and 50 mg or more of vitamin B6) after being discharged from the hospital, while another group of patients discontinued the vitamins upon discharge. Both groups continued to take their psychiatric medications. Those who continued to take the vitamins had a 50% lower re-admission rate compared with those who did not. Several later double-blind trials, including trials undertaken by the Canadian Mental Health Association, have been unable to reproduce these positive results. Early supporters of niacin therapy contend that many of these trials were poorly designed. One clinical trial reported no greater improvement in a group of schizophrenic patients given 6 grams of niacin than in others given 3 mg of niacin; all patients were also being treated with psychiatric medications. There are potential side-effects of niacin therapy, including an uncomfortable flushing sensation, dermatitis (skin inflammation), heartburn, aggravation of peptic ulcers, increased blood sugar, increased panic and anxiety, and elevation of liver enzymes, which may indicate damage to liver cells. A positive side effect of niacin therapy is reduction of cholesterol levels. Some of these effects, such as flushing, gastric upset, and reduction of serum cholesterol, do not occur with the use of . Because of the seriousness of some of these side effects, high amounts of should not be used without the supervision of a healthcare practitioner. Vitamin B6 has been used in combination with niacin in the orthomolecular approach to schizophrenia. Pioneers of orthomolecular medicine reported benefits from this combination. However, although two placebo-controlled trials found significant improvement when schizophrenic patients were given either 3 grams of niacin or 75 mg of pyridoxine along with their psychiatric medications, this improvement was lost when the two vitamins were combined. In a double-blind trial, schizophrenic patients were given either a vitamin program based on their individual laboratory tests or a placebo (25 mg of vitamin C) in addition to their psychiatric medications. The vitamin program included large amounts of various B vitamins, as well as vitamin C and vitamin E. After five months, the number of patients who improved was not different in the vitamin group compared with the placebo group. Clinical trials of the effects of vitamin B6 have yielded differing results. The results of supplementation with 100 mg daily in one schizophrenic patient included dramatic reduction in side effects from medication, as well as reduction in schizophrenic symptoms. In a preliminary trial, 60 mg per day of vitamin B6 resulted in symptomatic improvement in only 5% of schizophrenic patients after four weeks. Another preliminary trial, however, found that a higher amount of vitamin B6—50 mg three times daily given for eight to twelve weeks—in addition to psychiatric medications, did bring about significant improvements in schizophrenic patients. These patients experienced a better sense of well-being, increased motivation, and greater interest in their “personal habits and their environment.” |
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2 Stars
Type 1 Diabetes
Consult a qualified healthcare practitioner
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Taking vitamin B3 (as niacin or niacinamide) might prevent or limit the severity of type 1 diabetes.
High doses of niacin (a form of vitamin B3), such as 2 to 3 grams per day, are sometimes recommended to lower high triglyceride and cholesterol levels in people with type 1 diabetes. However, niacin’s ability to reduce cardiovascular risk in the context of type 1 diabetes has not been established. It is important to note that niacin doses this high, particularly in extended release formulations, may cause flushing, stomach upset, and liver toxicity, and should be used by people with diabetes only with medical supervision. Animal research suggests that niacinamide, a form of vitamin B3 with fewer side effects, may prevent toxic damage to the pancreatic cells that make insulin. Although one intriguing study found niacinamide supplementation was associated with a lower incidence of type 1 diabetes in children at high risk, more recent studies have not confirmed a protective effect. A controlled clinical trial in subjects with recently diagnosed type 1 diabetes found the addition of niacinamide (25 mg per day per kg of body weight; approximately 2–3 grams per day) to intensive insulin treatment led to greater improvement in HgA1c over two years, but other clinical trials have found no benefit on glucose metabolism in similar subjects. |
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1 Star
Alcohol Withdrawal
Refer to label instructions
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Preliminary research has suggested that niacin may help wean some alcoholics away from alcohol. Niacinamide—a safer form of the same vitamin—might have similar actions.
Many alcoholics are deficient in B vitamins, including . John Cleary, M.D., observed that some alcoholics spontaneously stopped drinking in association with taking niacin supplements (niacin is a form of vitamin B3). Cleary concluded that alcoholism might be a manifestation of niacin deficiency in some people and recommended that alcoholics consider supplementation with 500 mg of niacin per day. Without specifying the amount of niacin used, Cleary’s preliminary research findings suggested that niacin supplementation helped wean some alcoholics away from alcohol. Activated vitamin B3 used intravenously has also helped alcoholics quit drinking. Niacinamide—a safer form of the same vitamin—might have similar actions and has been reported to improve alcohol metabolism in animals. The daily combination of 3 grams of vitamin C, 3 grams of , 600 mg of vitamin B6, and 600 IU of vitamin E has been used by researchers from the University of Mississippi Medical Center in an attempt to reduce anxiety and depression in alcoholics. Although the effect of vitamin supplementation was no better than placebo in treating alcohol-associated depression, the vitamins did result in a significant drop in anxiety within three weeks of use. Because of possible side effects, anyone taking such high amounts of niacin and vitamin B6 must do so only under the care of a doctor. |
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1 Star
Anxiety
Refer to label instructions
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Niacinamide (a form of vitamin B3) has been shown in animals to work in the brain in ways similar to anxiety medications. One study found that niacinamide helped people get through withdrawal from benzodiazepines—a common problem.
Niacinamide (a form of ) has been shown in animals to work in the brain in ways similar to drugs such as benzodiazepines (Valium-type drugs), which are used to treat anxiety. One study found that niacinamide (not niacin) helped people get through withdrawal from benzodiazepines—a common problem. A reasonable amount of niacinamide to take for anxiety, according to some doctors, is up to 500 mg four times per day. |
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1 Star
Cataracts
40 mg daily with 3 mg daily vitamin B2
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Vitamin B3 is needed to protect glutathione, an important antioxidant in the eye.
People with low blood levels of antioxidants and those who eat few antioxidant-rich fruits and vegetables have been reported to be at high risk for cataracts. Vitamin B2 and are needed to protect glutathione, an important antioxidant in the eye. Vitamin B2 deficiency has been linked to cataracts. Older people taking 3 mg of vitamin B2 and 40 mg of vitamin B3 per day were partly protected against cataracts in one trial. However, the intake of vitamin B2 in China is relatively low, and it is not clear whether supplementation would help prevent cataracts in populations where vitamin B2 intake is higher. |
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1 Star
High Cholesterol
400 to 500 mg of inositol hexaniacinate three to four times daily
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Inositol hexaniacinate, a special form of niacin, does not appear to improve cholesterol levels.
In an attempt to avoid the side effects of niacin (vitamin B3), inositol hexaniacinate (also called ) is sometimes recommended instead of niacin. This special compound contains six molecules of niacin bound to a single molecule of inositol, and the niacin in this compound is released slowly. Early reports suggested inositol hexaniacinate could lower serum cholesterol without toxic effects. However, in a placebo-controlled trial in 120 participants with mildly to moderately elevated cholesterol levels, 1,500 mg of inositol hexaniacinate for six weeks had no impact on lipid levels. Similarly, a crossover trial also found inositol hexaniacinate had no significant effect on cholesterol levels.
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1 Star
High Cholesterol
1,500 to 3,000 mg daily under a doctor's supervision
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High amounts (several grams per day) of niacin, a form of vitamin B3, have been shown to raise HDL-cholesterol and lower LDL-cholesterol levels; however, niacin therapy has not been found to reduce the incidence of cardiovascular events and has substantial toxicity.
, or nicotinic acid, is a form of vitamin B3. High amounts of niacin, such as 1.5–3 grams per day, have been shown to improve lipid profiles, mainly by raising HDL-cholesterol levels. A review of clinical trials found 3 grams per day of niacin can lower total cholesterol levels by 12.6%, lower LDL-cholesterol levels by 15.4%, and raise HDL-cholesterol levels by 22.5%. Niacin was widely used as a prescription medication for treating high cholesterol before the introduction and success of statin drugs, but more recent research has shown niacin therapy and other treatments that increase low HDL-cholesterol levels have little impact on cardiovascular outcomes and its use is generally no longer recommended. Another challenge with niacin therapy is toxicity: acute flushing, headache, and stomachache from high-dose niacin limit its tolerability, and chronic toxic effects, such as liver toxicity and musculoskeletal damage, can be severe. Serious toxic events are more common with sustained release formulations. Therefore, high intakes of niacin must only be taken under the supervision of a doctor. Importantly, another form of vitamin B3 called niacinamide (also nicotinamide) has no effect on cholesterol levels and does not have the same toxic effects.
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1 Star
HIV and AIDS Support
Refer to label instructions
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Vitamin B3 may play a role in HIV prevention and treatment. A form of vitamin B3 (niacinamide) has been shown to inhibit HIV in test tube studies.
Preliminary observations suggest a possible role for in HIV prevention and treatment. A form of vitamin B3 (niacinamide) has been shown to inhibit HIV in test tube studies. However, no published data have shown vitamin B3 to inhibit HIV in animals or in people. One study did show that HIV-positive people who consume more than 64 mg of vitamin B3 per day have a decreased risk of progression to AIDS or AIDS-related death. Clinical trials in humans are required to validate these preliminary observations. |
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1 Star
Hypoglycemia
Refer to label instructions
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Research has shown that supplementing with niacinamide (vitamin B3) can prevent blood sugar levels from falling excessively in people with hypoglycemia.
Research has shown that supplementing with chromium (200 mcg per day) or magnesium (340 mg per day) can prevent blood sugar levels from falling excessively in people with hypoglycemia. (vitamin B3) has also been found to be helpful for hypoglycemic people. Other nutrients, including vitamin C, vitamin E, zinc, copper, manganese, and vitamin B6, may help control blood sugar levels in diabetics. Since there are similarities in the way the body regulates high and low blood sugar levels, these nutrients might be helpful for hypoglycemia as well, although the amounts needed for that purpose are not known. |
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1 Star
Hypothyroidism
Refer to label instructions
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Vitamin B3 (niacin) supplementation may decrease thyroid hormone levels.
Preliminary data indicate that (niacin) supplementation may decrease thyroid hormone levels. In one small study, 2.6 grams of niacin per day helped lower blood fat levels. After a year or more, thyroid hormone levels had fallen significantly in each person, although none experienced symptoms of hypothyroidism. In another case report, thyroid hormone levels decreased in two people who were taking niacin for high cholesterol and triglycerides; one of these two was diagnosed with hypothyroidism. When the niacin was discontinued for one month, thyroid hormone levels returned to normal. |
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1 Star
Multiple Sclerosis
Refer to label instructions
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Thiamine (vitamin B1) deficiency may contribute to nerve damage. Researchers have found that injections of thiamine or thiamine combined with niacin (vitamin B3) may reduce symptoms.
Deficiency of thiamine may contribute to nerve damage. Many years ago, researchers found that injecting thiamine into the spinal cord or using intravenous thiamine combined with niacin in people with MS led to a reduction in symptoms. Using injectable vitamins requires medical supervision. No research has yet studied the effects of oral supplementation with B vitamins in people with MS.
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1 Star
Photosensitivity
Refer to label instructions
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Niacinamide, a form of vitamin B3, can reduce the formation of a kynurenic acid—a substance that has been linked to photosensitivity.
, a form of vitamin B3, can reduce the formation of a kynurenic acid—a substance that has been linked to photosensitivity. One trial studied the effects of niacinamide in people who had polymorphous light eruption. While taking one gram three times per day, most people remained free of problems, despite exposure to the sun. Because of the potential for adverse effects, people taking this much niacinamide should do so only under medical supervision. |
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1 Star
Tardive Dyskinesia
Refer to label instructions
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In some studies, taking vitamin B3 as niacin or niacinamide, along with other nutrients, appeared to prevent the development of tardive dyskinesia.
During a ten-year period, doctors at the North Nassau Mental Health Center in New York treated approximately 11,000 people with schizophrenia with a megavitamin regimen that included vitamin C (up to 4 grams per day), —either as niacin or niacinamide—(up to 4 grams per day), vitamin B6 (up to 800 mg per day), and vitamin E (up to 1,200 IU per day). During that time, not a single new case of TD was seen, even though many of the people were taking neuroleptic drugs. Another psychiatrist who routinely used , vitamin C, and vitamin B-complex over a 28-year period rarely saw TD develop in her patients. Further research is needed to determine which nutrients or combinations of nutrients were most important for preventing TD. The amounts of niacinamide and vitamin B6 used in this research may cause significant side effects and may require monitoring by a doctor. |
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1 Star
Type 2 Diabetes
Less than 2 grams daily
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Dietary niacin (vitamin B3) is important for healthy management of cholesterol and triglycerides; however, high dose supplementation with niacin could worsen glycemic control in people with type 2 diabetes.
Vitamin B3 (niacin) is an important nutrient for regulating lipid metabolism and has well established positive effects on cholesterol and triglyceride levels. High dietary intake of niacin may protect against diabetes-related fatty liver. Unfortunately, the intake of therapeutic amounts of niacin, such as 2 to 3 grams per day, has been associated with an increased risk of type 2 diabetes and worsening of blood glucose control in people with diabetes. A microencapsulated niacin (but not niacinamide) product, however, was found in a pilot trial to improve insulin sensitivity in men with obesity, possibly by altering the gut microbiome. The potential benefits of microencapsulated niacin in type 2 diabetes remain to be investigated.
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How It Works
How to Use It
In part because it is added to white flour, most people generally get enough vitamin B3 from their diets to prevent a deficiency. However, 10–25 mg of the vitamin can be taken as part of a B-complex or multivitamin supplement. Larger amounts are used for the treatment of various health conditions.
Where to Find It
The best food sources of vitamin B3 are peanuts, brewer’s yeast, fish, and meat. Some vitamin B3 is also found in whole grains.
Possible Deficiencies
Pellagra, the disease caused by a vitamin B3 deficiency, is rare in Western societies. Symptoms include loss of appetite, skin rash, diarrhea, mental changes, beefy tongue, and digestive and emotional disturbance.
Best Form to Take
Vitamin B3 occurs naturally in two forms: niacin (or nicotinic acid) and niacinamide (or nicotinamide). There are important differences between the forms when it comes to effectiveness and side effects. In very large doses (more than 3 grams a day), both forms may cause reversible hepatotoxicity (liver damage). However, niacinamide does not appear to have the other side effects associated with niacin, such as skin flushing, itching, and urticaria. Time-release niacin may reduce the risk of skin flushing, but such preparations raise even greater concerns about hepatotoxicity. Niacin improves serum lipid levels, whereas niacinamide does not. Niacinamide is used more often than niacin for conditions that respond to vitamin B3, because of its lower toxicity profile.1
Interactions
Interactions with Supplements, Foods, & Other Compounds
Vitamin B3 works with vitamin B1 and vitamin B2 to release energy from carbohydrates. Therefore, these vitamins are often taken together in a B-complex or multivitamin supplement (although most B3 research uses niacin or niacinamide alone).
Interactions with Medicines
Certain medicines interact with this supplement.
Replenish Depleted Nutrients
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Carbidopa
A study in animals has found that carbidopa inhibits an enzyme involved in the synthesis of niacin in the body. In addition, there is evidence that niacin synthesis is decreased in people taking carbidopa and other drugs in its class, raising the concern that people taking these drugs could be at risk of niacin deficiency, even if not frankly deficient. Further studies will be required determine if niacin supplementation is appropriate in people taking carbidopa.
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Carbidopa-Levodopa
A study in animals has found that carbidopa inhibits an enzyme involved in the synthesis of niacin in the body. In addition, there is evidence that niacin synthesis is decreased in people taking carbidopa and other drugs in its class. Further studies are needed to determine whether niacin supplementation is appropriate in people taking carbidopa.
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Desogestrel-Ethinyl Estradiol
A review of literature suggests that women who use oral contraceptives may experience decreased vitamin B1, B2, , B12, C, and zinc levels. Oral contraceptive use has been associated with increased absorption of calcium and copper and with increased blood levels of copper and vitamin A. Oral contraceptives may interfere with manganese absorption. The clinical importance of these actions remains unclear.
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Ethinyl Estradiol and Levonorgestrel
A review of literature suggests that women who use oral contraceptives may experience decreased vitamin B1, B2, , B12, C, and zinc levels. Oral contraceptive use has been associated with increased absorption of calcium and copper and with increased blood levels of copper and vitamin A. Oral contraceptives may interfere with manganese absorption. The clinical importance of these actions remains unclear.
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Ethinyl Estradiol and Norethindrone
A review of literature suggests that women who use OCs may experience decreased vitamin B1, B2, , B12, C, and zinc levels. OC use has been associated with increased absorption of calcium and copper and with increased blood levels of copper and vitamin A. OCs may interfere with manganese absorption. The clinical importance of these actions remains unclear.
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Ethinyl Estradiol and Norgestimate
A review of literature suggests that women who use OCs may experience decreased vitamin B1, B2, , B12, C, and zinc levels. OC use has been associated with increased absorption of calcium and copper and with increased blood levels of copper and vitamin A. OCs may interfere with manganese absorption. The clinical importance of these actions remains unclear.
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Ethinyl Estradiol and Norgestrel
A review of literature suggests that women who use oral contraceptives may experience decreased vitamin B1, B2, , B12, C, and zinc levels. Oral contraceptive use has been associated with increased absorption of calcium and copper and with increased blood levels of copper and vitamin A. Oral contraceptives may interfere with manganese absorption. The clinical importance of these actions remains unclear.
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Isoniazid
Isoniazid is capable of causing vitamin B3 (niacin) deficiency, most likely due to its ability to interfere with cell-repair enzymes made from niacin. Significant niacin deficiency, also known as pellagra, features dermatitis, diarrhea, and dementia (impaired intellectual function). Supplementation with vitamin B6 is thought to reduce this risk, although small amounts (e.g. 10 mg daily) has been noted to be inadequate in some cases.
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Levonorgestrel
A review of literature suggests that women who use oral contraceptives may experience decreased vitamin B1, B2, , B12, C, and zinc levels. Oral contraceptive use has been associated with increased absorption of calcium and copper and with increased blood levels of copper and vitamin A. Oral contraceptives may interfere with manganese absorption. The clinical importance of these actions remains unclear.
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Levonorgestrel-Ethinyl Estrad
A review of literature suggests that women who use oral contraceptives may experience decreased vitamin B1, B2, , B12, C, and zinc levels. Oral contraceptive use has been associated with increased absorption of calcium and copper and with increased blood levels of copper and vitamin A. Oral contraceptives may interfere with manganese absorption. The clinical importance of these actions remains unclear.
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Mestranol and Norethindrone
A review of literature suggests that women who use oral contraceptives may experience decreased vitamin B1, B2, , B12, C, and zinc levels. Oral contraceptive use has been associated with increased absorption of calcium and copper and with increased blood levels of copper and vitamin A. Oral contraceptives may interfere with manganese absorption. The clinical importance of these actions remains unclear.
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Norgestimate-Ethinyl Estradiol
A review of literature suggests that women who use oral contraceptives may experience decreased vitamin B1, B2, , B12, C, and zinc levels. Oral contraceptive use has been associated with increased absorption of calcium and copper and with increased blood levels of copper and vitamin A. Oral contraceptives may interfere with manganese absorption. The clinical importance of these actions remains unclear.
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Tetracycline
Taking large amounts of niacinamide, a form of , can suppress inflammation in the body. According to numerous preliminary reports, niacinamide, given in combination with tetracycline or minocycline, may be effective against bullous pemphigoid, a benign, autoimmune blistering disease of the skin. Preliminary evidence also suggests a similar beneficial interaction may exist between tetracycline and niacinamide in the treatment of dermatitis herpetiformis.
Reduce Side Effects
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none
Support Medicine
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Amitriptyline
Combination of 6 grams per day L-tryptophan and 1,500 mg per day (a form of vitamin B3) with imipramine has shown to be more effective than imipramine alone for people with bipolar disorder. These levels did not improve the effects of imipramine in people with depression. Lower amounts (4 grams per day of L-tryptophan and 1,000 mg per day of niacinamide) did show some tendency to enhance the effect of imipramine.
The importance of the amount of L-tryptophan was confirmed in other studies, suggesting that if too much L-tryptophan (6 grams per day) is used, it is not beneficial, while levels around 4 grams per day may make tricyclic antidepressants work better.
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Amoxapine
Combination of 6 grams per day L-tryptophan and 1,500 mg per day (a form of vitamin B3) with imipramine has shown to be more effective than imipramine alone for people with bipolar disorder. These levels did not improve the effects of imipramine in people with depression. Lower amounts (4 grams per day of L-tryptophan and 1,000 mg per day of niacinamide) did show some tendency to enhance the effect of imipramine.
The importance of the amount of L-tryptophan was confirmed in other studies, suggesting that if too much L-tryptophan (6 grams per day) is used, it is not beneficial, while levels around 4 grams per day may make tricyclic antidepressants work better.
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Benztropine
Akathisia is an adverse reaction to anti-psychotic drugs, where a person has an uncontrollable desire to be in constant motion. One preliminary report suggested that 4,000 mg of L-tryptophan and 25 mg niacin per day taken with benztropine enhances the treatment of akathisia. Controlled studies are necessary to determine whether L-tryptophan and niacin supplements might benefit most people taking benztropine who experience adverse reactions to anti-psychotic drugs.
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Clomipramine
Combination of 6 grams per day L-tryptophan and 1,500 mg per day (a form of vitamin B3) with imipramine has shown to be more effective than imipramine alone for people with bipolar disorder. These levels did not improve the effects of imipramine in people with depression. Lower amounts (4 grams per day of L-tryptophan and 1,000 mg per day of niacinamide) did show some tendency to enhance the effect of imipramine.
The importance of the amount of L-tryptophan was confirmed in other studies, suggesting that if too much L-tryptophan (6 grams per day) is used, it is not beneficial, while levels around 4 grams per day may make tricyclic antidepressants work better.
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Doxepin
Combination of 6 grams per day L-tryptophan and 1,500 mg per day (a form of vitamin B3) with imipramine has shown to be more effective than imipramine alone for people with bipolar disorder. These levels did not improve the effects of imipramine in people with depression. Lower amounts (4 grams per day of L-tryptophan and 1,000 mg per day of niacinamide) did show some tendency to enhance the effect of imipramine.
The importance of the amount of L-tryptophan was confirmed in other studies, suggesting that if too much L-tryptophan (6 grams per day) is used, it is not beneficial, while levels around 4 grams per day may make tricyclic antidepressants work better.
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Gemfibrozil
Niacin (not niacinamide) and gemfibrozil have successfully raised HDL (good) cholesterol levels, both alone and in combination.
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Imipramine
Combination of 6 grams per day L-tryptophan and 1,500 mg per day (a form of vitamin B3) with imipramine has shown to be more effective than imipramine alone for people with bipolar disorder. These levels did not improve the effects of imipramine in people with depression. Lower amounts (4 grams per day of L-tryptophan and 1,000 mg per day of niacinamide) did show some tendency to enhance the effect of imipramine.
The importance of the amount of L-tryptophan was confirmed in other studies, suggesting that if too much L-tryptophan (6 grams per day) is used, it is not beneficial, while levels around 4 grams per day may make tricyclic antidepressants work better.
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Minocycline
Niacinamide taken in combination with minocycline has produced beneficial effects in an individual with cicatricial pemphigoid, an autoimmune blistering disease, as well as in a 46-year-old woman with pemphigus vegetans, another blistering disease. Several other studies have confirmed the efficacy of this combination for bullous (blistering) pemphigoid.
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Nortriptyline
Combination of 6 grams per day L-tryptophan and 1,500 mg per day (a form of vitamin B3) with imipramine has shown to be more effective than imipramine alone for people with bipolar disorder. These levels did not improve the effects of imipramine in people with depression. Lower amounts (4 grams per day of L-tryptophan and 1,000 mg per day of niacinamide) did show some tendency to enhance the effect of imipramine.
The importance of the amount of L-tryptophan was confirmed in other studies, suggesting that if too much L-tryptophan (6 grams per day) is used, it is not beneficial, while levels around 4 grams per day may make tricyclic antidepressants work better.
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Protriptyline
Combination of 6 grams per day L-tryptophan and 1,500 mg per day (a form of vitamin B3) with imipramine has shown to be more effective than imipramine alone for people with bipolar disorder. These levels did not improve the effects of imipramine in people with depression. Lower amounts (4 grams per day of L-tryptophan and 1,000 mg per day of niacinamide) did show some tendency to enhance the effect of imipramine.
The importance of the amount of L-tryptophan was confirmed in other studies, suggesting that if too much L-tryptophan (6 grams per day) is used, it is not beneficial, while levels around 4 grams per day may make tricyclic antidepressants work better.
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Thioridazine
In a controlled study, individuals taking thioridazine for psychosis cooperated better and withdrew less from other people when niacin (nicotinic acid), 300–1,500 mg each day, was added. Whether people who are taking thioridazine for other mental health problems might benefit from niacin supplementation is unknown.
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Trimipramine
Combination of 6 grams per day L-tryptophan and 1,500 mg per day (a form of vitamin B3) with imipramine has shown to be more effective than imipramine alone for people with bipolar disorder. These levels did not improve the effects of imipramine in people with depression. Lower amounts (4 grams per day of L-tryptophan and 1,000 mg per day of niacinamide) did show some tendency to enhance the effect of imipramine.
The importance of the amount of L-tryptophan was confirmed in other studies, suggesting that if too much L-tryptophan (6 grams per day) is used, it is not beneficial, while levels around 4 grams per day may make tricyclic antidepressants work better.
Reduces Effectiveness
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none
Potential Negative Interaction
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Glimepiride
Vitamin B3 can raise blood sugar levels, which makes diabetes difficult to control. Use of niacin along with glimepiride may increase requirements for the drug. On the other hand, individuals who stop taking niacin while on glimepiride should monitor their blood for lower-than-usual glucose levels.
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Repaglinide
Supplementation with large amounts of niacin (also called nicotinic acid) can increase blood glucose levels in diabetics, which might interfere with the blood-sugar-lowering effects of repaglinide. The form of vitamin B3 known as niacinamide does not have this effect. People who start or stop supplementing niacin while on repaglinide should carefully monitor their blood sugar levels and consult their prescribing doctor about making adjustments in the daily amount of drug taken.
Explanation Required
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Atorvastatin
Niacin is the form of vitamin B3 used to lower cholesterol. Ingestion of large amounts of niacin along with lovastatin (a drug closely related to atorvastatin) or with atorvastatin itself may cause muscle disorders (myopathy) that can become serious (rhabdomyolysis). Such problems appear to be uncommon when HMG-CoA reductase inhibitors are combined with niacin. Moreover, concurrent use of niacin with HMG-CoA reductase inhibitors has been reported to enhance the cholesterol-lowering effect of the drugs. Individuals taking atorvastatin should consult their physician before taking niacin.
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Cerivastatin
Some sources have reported that taking niacin (vitamin B3) together with HMG-CoA reductase inhibitors may result in serious muscle damage. However, niacin has also been used in combination with statin drugs without ill effects, and has been found to enhance the cholesterol-lowering effect of these drugs. Persons taking cerivastatin or any other HMG-CoA reductase inhibitor should consult with their doctor before taking niacin.
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Fluvastatin
Niacin is the form of vitamin B3 used to lower cholesterol. Fluvastatin and niacin used together have been shown to be more effective than either substance alone. Ingestion of large amounts of niacin along with HMG-CoA reductase inhibitors such as fluvastatin may cause muscle disorders (myopathy) that can become serious (rhabdomyolysis). Such problems appear to be uncommon. Nonetheless, individuals taking fluvastatin should consult with their doctor before taking niacin.
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Lovastatin
Niacin is a vitamin used to lower cholesterol. Large amounts of niacin taken with lovastatin have been reported to cause potentially serious muscle disorders (myopathy or rhabdomyolysis). However, niacin also enhances the cholesterol-lowering effect of lovastatin. Taking as little as 500 mg three times per day of niacin with lovastatin has been shown to have these complementary, supportive actions with almost none of the side effects seen when higher amounts of niacin are taken. Nevertheless, individuals taking lovastatin should consult with their doctor before taking niacin.
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Pravastatin
Niacin is a vitamin used to lower cholesterol. Sixteen people with diabetes and high cholesterol were given pravastatin plus niacin to lower cholesterol. Niacin was added over a two week period, to a maximum amount of 500 mg three times per day. The combination of pravastatin plus niacin was continued for four weeks. Compared with pravastatin, niacin plus pravastatin resulted in significantly reduced cholesterol levels. Others have also shown that the combination of pravastatin and niacin is more effective in lowering cholesterol levels than is pravastatin alone. However, large amounts of niacin taken with pravastatin might cause serious muscle disorders (myopathy or rhabdomyolysis). Individuals taking pravastatin should consult a doctor before taking niacin.
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Rosuvastatin
A recent blinded study showed that individuals taking both rosuvastatin and niacin had a greater increase in HDL (“good”) cholesterol and apolipoprotein A-I than did those taking rosuvastatin alone. People taking rosuvastatin might benefit from taking niacin, though they should consult with their healthcare provider before starting the supplement. When taken with niacin, some statin drugs may become more toxic so there is a possibility of an adverse interaction.
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Simvastatin
Niacin is the form of vitamin B3 used to lower cholesterol. Taking large amounts of niacin along with HMG-CoA reductase inhibitors may cause muscle disorders (myopathy) that can become serious (rhabdomyolysis). Such problems appear to be uncommon. Moreover, concurrent use of niacin has been reported to enhance the cholesterol-lowering effect of HMG-CoA reductase inhibitors. Individuals taking simvastatin should consult a doctor before taking niacin.
Side Effects
Side Effects
Niacinamide is almost always safe to take in amounts of 1,000 mg per day or less, though rare liver problems have occurred at amounts in excess of 1,000 mg per day. Niacin, in amounts as low as 50–100 mg, may cause flushing, headache, and stomachache in some people. Doctors sometimes prescribe very high amounts of niacin (as much as 3,000 mg per day or more) for certain health problems. These large amounts can cause liver damage, diabetes, gastritis, damage to eyes, and elevated blood levels of uric acid (which can cause gout).2 Symptoms caused by niacin supplements, such as flushing, have been reduced with sustained-release (also called ‘time-release’) niacin products. However, sustained-release forms of niacin have caused significant liver toxicity in some cases and, rarely, liver failure.3, 4, 5, 6, 7 One partial time-release (intermediate-release) niacin product has demonstrated clinical efficacy without flushing, and also with much less of the liver function abnormalities typically associated with sustained-release niacin formulations.8 However, this form of niacin is available by prescription only.
In a controlled clinical trial, 1,000 mg or more per day of niacin raised blood levels of homocysteine, a substance associated with increased risk of heart disease.9 Since other actions of niacin lower heart disease risk,10, 11 the importance of this finding is unclear. Nonetheless, for all of the reasons discussed above, large amounts of niacin should never be taken without consulting a doctor.
The inositol hexaniacinate form of niacin has not been linked with the side effects associated with niacin supplementation. In a group of people being treated alternatively with niacin and inositol hexaniacinate for skin problems, niacin supplementation (50–100 mg per day) was associated with numerous side effects, including skin flushing, nausea, vomiting and agitation.12 In contrast, people taking inositol hexaniacinate experienced no complaints whatsoever, even at amounts two to five times higher than the previously used amounts of niacin. However, the amount of research studying the safety of inositol hexaniacinate remains quite limited. Therefore, people taking this supplement in large amounts (2,000 mg or more per day) should be under the care of a doctor.
References
1. Gaby, AR. Nutritional Medicine. Concord, NH: Fritz Perlberg Publishing, 2011.
2. Goldie C, Taylor AJ, Nguyen P, et al. Niacin therapy and the risk of new-onset diabetes: a meta-analysis of randomised controlled trials. Heart 2016;102:198–203.
3. McKenney JM, Proctor JD, Harris S, Chinchili VM. A comparison of the efficacy and toxic effects of sustained—vs immediate-release niacin in hypercholesterolemic patients. JAMA 1994;271:672-7.
4. Knopp RH, Ginsberg J, Albers JJ, et al. Contrasting effects of unmodified and time-release forms of niacin on lipoproteins in hyperlipidemic subjects: clues to mechanism of action of niacin. Metabolism 1985;34:642-50.
5. Gray DR, Morgan T, Chretien SD, Kashyap ML. Efficacy and safety of controlled-release niacin in dyslipoproteinemic veterans. Ann Intern Med 1994;121:252-8.
6. Rader JI, Calvert RJ, Hathcock JN. Hepatic toxicity of unmodified and time-release preparations of niacin. Am J Med 1992;92:77-81 [Review].
7. Knopp RH. Niacin and hepatic failure. Ann Intern Med 1989;111:769 [letter].
8. Goldberg A, Alagona P Jr, Capuzzi DM, et al. Multiple-dose efficacy and safety of an extended-release form of niacin in the management of hyperlipidemia. Am J Cardiol 2000;85:1100-5.
9. Garg R, Malinow M, Pettinger M, Upson B, Hunninghake D. Niacin treatment increases plasma homocyst(e)ine levels. Am Heart J 1999;138:1082-7.
10. Brown WV. Niacin for lipid disorders. Postgrad Med 1995;98:185-93 [review].
11. Guyton JR. Effect of niacin on atherosclerotic cardiovascular disease. Am J Cardiol 1998;82(12A):18U-23U [review].
12. Welsh AL, Ede M. Inositol hexanicotinate for improved nicotinic acid therapy. Int Record Med 1961;174:9–15.
Last Review: 06-01-2015
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The information presented by TraceGains is for informational purposes only. It is based on scientific studies (human, animal, or in vitro), clinical experience, or traditional usage as cited in each article. The results reported may not necessarily occur in all individuals. For many of the conditions discussed, treatment with prescription or over the counter medication is also available. Consult your doctor, practitioner, and/or pharmacist for any health problem and before using any supplements or before making any changes in prescribed medications. Information expires December 2025.
