Niacin

Print

What is it?

Niacin is a form of vitamin B3. It is found in foods such as yeast, meat, fish, milk, eggs, green vegetables, and cereal grains. Niacin is also produced in the body from tryptophan, which is found in protein-containing food. When taken as a supplement, niacin is often found in combination with other B vitamins.

Do not confuse niacin with NADH, niacinamide, inositol nicotinate, IP-6, or tryptophan. See the separate listings for these topics.

Prescription forms of niacin are approved by the US Food and Drug Administration (FDA) for high cholesterol and to increase levels of a specific type of good cholesterol, known as HDL. Niacin supplements and prescription products are also taken by mouth for preventing vitamin B3 deficiency and related conditions such as pellagra.

It is effective?
Natural Medicines rates effectiveness based on scientific evidence according to the following scale: Effective, Likely Effective, Possibly Effective, Possibly Ineffective, Likely Ineffective, Ineffective, and Insufficient Evidence to Rate.

Probably Effective for …

  • Abnormal levels of cholesterol or blood fats (dyslipidemia). Some niacin products are approved by the U.S. Food and Drug Administration (FDA) as prescription products for treating abnormal levels of blood fats. These prescription niacin products typically come in high strengths of 500 mg or higher. Dietary supplement forms of niacin usually come in strengths of 250 mg or less. Since very high doses of niacin are required for improving cholesterol levels, dietary supplement niacin usually isn’t appropriate. Niacin may be combined with other cholesterol-lowering drugs when diet and single-drug therapy is not enough. Niacin improves cholesterol levels, but does not improve cardiovascular outcomes such as heart attacks and strokes.
  • A disease caused by niacin deficiency (pellagra). Niacin is approved by the U.S. Food and Drug Administration (FDA) for this use. However, niacin can cause “flushing” (redness, itching, and tingling). So another product, called niacinamide, is sometimes preferred because it doesn’t cause this side effect.

Possibly Effective for …

  • Abnormal levels of blood fats in people with HIV/AIDS. Taking niacin seems to improve levels of cholesterol and blood fats called triglycerides in patients with this condition.
  • A grouping of symptoms that increase the risk of diabetes, heart disease, and stroke (metabolic syndrome). Taking niacin seems to increase levels of high-density lipoprotein (HDL or “good”) cholesterol and reduce levels of blood fats called triglycerides in people with metabolic syndrome. Taking the niacin along with a prescription omega-3 fatty acid seems to work even better.

Ineffective for …

  • Heart disease. High quality research shows that niacin does not prevent heart attack or stroke in people who take niacin to prevent or treat heart disease. Niacin has also not been shown to reduce the risk of death. Niacin should not be taken to treat or prevent heart disease.

Insufficient Evidence to Make a Determination for …

  • Hardening of the arteries (atherosclerosis). Taking niacin by mouth along with medicines called bile acid sequestrants might reduce hardening of the arteries in men with this condition. It seems to work best in men with high levels of blood fats called triglycerides. But taking niacin does not seem to reduce hardening of the arteries in patients with a condition called peripheral arterial disease (PAD). Also, niacin does not prevent cardiovascular events such as a heart attack or stroke.
  • Alzheimer disease. People who consume higher amounts of niacin from food and multivitamins seem to have a lower risk of getting Alzheimer disease than people who consume less niacin. But there is no evidence that taking a niacin supplement helps to prevent Alzheimer disease.
  • Cataracts. People who eat a diet high in niacin might have a reduced chance of developing nuclear cataracts. Nuclear cataract is the most common type of cataract. The effect of taking niacin supplementation is unknown.
  • An infection of the intestines that causes diarrhea (cholera). Taking niacin by mouth seems to reduce diarrhea in people with cholera.
  • Erectile dysfunction (ED). Taking extended-release niacin at bedtime for 12 weeks seems to help men who have ED and high lipid levels maintain an erection during sexual intercourse.
  • High levels of phosphate in the blood (hyperphosphatemia). People with kidney failure might have high blood levels of phosphate. Some early research shows that taking niacin can reduce blood levels of phosphate in people with end-stage kidney disease and high levels of blood phosphate. But other research shows that taking niacin does not lower blood phosphate levels in people who are also taking medications used to lower blood phosphate levels.
  • Blockage of the vein in the eye (retinal vein occlusion): Early research shows that taking niacin might improve eyesight in people with this condition.
  • Sickle cell disease: Early research shows that taking niacin does not improve the levels of blood fats in people with sickle cell disease.
  • Acne.
  • Alcohol use disorder.
  • Athletic performance.
  • Attention deficit-hyperactivity disorder (ADHD).
  • Depression.
  • Dizziness.
  • Drug-induced hallucinations.
  • Migraine.
  • Motion sickness.
  • Schizophrenia.
  • Other conditions.

More evidence is needed to rate niacin for these uses.

How does it work?
Niacin is absorbed by the body when dissolved in water and taken by mouth. It is converted to niacinamide if taken in amounts greater than what is needed by the body.

Niacin is required for the proper function of fats and sugars in the body and to maintain healthy cells. At high doses, niacin might help people with heart disease because of its beneficial effects on clotting. It may also improve levels of a certain type of fat called triglycerides in the blood.

Niacin deficiency can cause a condition called pellagra, which causes skin irritation, diarrhea, and dementia. Pellagra was common in the early twentieth century, but is less common now, since some foods containing flour are now fortified with niacin. Pellagra has been virtually eliminated in western culture.

People with poor diet, alcoholism, and some types of slow-growing tumors called carcinoid tumors might be at risk for niacin deficiency.

Is there concern for the safety of its use?
When taken by mouth:

Niacin is LIKELY SAFE for most people when taken appropriately. Prescription products containing niacin are safe when taken as directed. Niacin-containing foods or niacin supplements are safe when taken in doses lower than 35 mcg daily.

A common side effect of niacin is a flushing reaction. This might cause burning, tingling, itching, and redness of the face, arms, and chest, as well as headaches. Starting with small doses of niacin and taking 325 mg of aspirin before each dose of niacin will help reduce the flushing reaction. Usually, this reaction goes away as the body gets used to the medication. Alcohol can make the flushing reaction worse. Avoid large amounts of alcohol while taking niacin.

Other minor side effects of niacin are stomach upset, intestinal gas, dizziness, pain in the mouth, and other problems.

When doses of over 3 grams per day of niacin are taken, more serious side effects can happen. These include liver problems, gout, ulcers of the digestive tract, loss of vision, high blood sugar, irregular heartbeat, and other serious problems.

Special Precautions & Warnings:

Pregnancy and breast-feeding: Niacin is LIKELY SAFE for pregnant and breast-feeding women when taken by mouth in the recommended amounts. The maximum recommended amount of niacin for pregnant or breast-feeding women is 30 mg per day for women under 18 years of age, and 35 mg for women over 18.

Children: Niacin is LIKELY SAFE when taken by mouth in the recommended amounts for each age group. But children should avoid taking doses of niacin above the daily upper limits, which are 10 mg for children 1-3 years of age, 15 mg for children 4-8 years of age, 20 mg for children 9-13 years of age, and 30 mg for children 14-18 years of age.

Allergies: Niacin might worsen allergies by causing histamine, the chemical responsible for allergic symptoms, to be released.

Heart disease/unstable angina: Large amounts of niacin can increase the risk of irregular heartbeat. Use with caution.

Crohn disease: People with Crohn disease might have low niacin levels and require supplementation during flare-ups.

Diabetes: Niacin might increase blood sugar. People with diabetes who take niacin should check their blood sugar carefully.

Gallbladder disease: Niacin might make gallbladder disease worse.

Gout: Large amounts of niacin might bring on gout.

Kidney disease: Niacin might accumulate in people with kidney disease. This might cause harm.

Liver disease: Niacin might increase liver damage. Don’t use large amounts if you have liver disease.

Stomach or intestinal ulcers: Niacin might make ulcers worse. Don’t use large amounts if you have ulcers.

Very low blood pressure: Niacin might lower blood pressure and worsen this condition.

Surgery: Niacin might interfere with blood sugar control during and after surgery. Stop taking niacin at least 2 weeks before a scheduled surgery.

Fatty deposits around tendons (tendon xanthomas): Niacin might increase the risk of infections in xanthomas.

Thyroid disorders: Thyroxine is a hormone produced by the thyroid gland. Niacin might lower blood levels of thyroxine. This might worsen symptoms of certain thyroid disorders.

Are there any drug interactions?

Alcohol (ethanol)

Interaction Rating=Moderate Be cautious with this combination.

Niacin can cause flushing and itchiness. Consuming alcohol along with niacin might make the flushing and itching worse. There is also some concern that consuming alcohol with niacin might increase the chance of having liver damage.

Allopurinol (Zyloprim)

Interaction Rating=Moderate Be cautious with this combination.

Allopurinol (Zyloprim) is used to treat gout. Taking large doses of niacin might worsen gout and decrease the effectiveness of allopurinol (Zyloprim).

Aspirin

Interaction Rating=Minor Be watchful with this combination.

Aspirin is often used with niacin to reduce the flushing caused by niacin. Taking high doses of aspirin might decrease how fast the body gets rid of niacin. This could cause there to be too much niacin in the body and possibly lead to side effects. But the low doses of aspirin most commonly used for niacin-related flushing don’t seem to be a problem.

Carbamazepine (Tegretol)

Interaction Rating=Moderate Be cautious with this combination.

Carbamazepine (Tegretol) is broken down by the body. There is some concern that niacinamide might decrease how fast the body breaks down carbamazepine (Tegretol). But there is not enough information to know if this is important.

Clonidine (Catapres)

Interaction Rating=Moderate Be cautious with this combination.

Clonidine and niacin both lower blood pressure. Taking both niacin with clonidine might cause your blood pressure to become too low.

Medications for diabetes (Antidiabetes drugs)

Interaction Rating=Moderate Be cautious with this combination.

Long-term use of niacin and niacinamide might increase blood sugar. By increasing blood sugar, niacin and niacinamide might decrease the effectiveness of diabetes medications. Monitor your blood sugar closely. The dose of your diabetes medication might need to be changed.

Some medications used for diabetes include glimepiride (Amaryl), glyburide (DiaBeta, Glynase PresTab, Micronase), insulin, pioglitazone (Actos), rosiglitazone (Avandia), metformin (Glucophage), nateglinide (Starlix), repaglinide (Prandin), chlorpropamide (Diabinese), glipizide (Glucotrol), tolbutamide (Orinase), and others.

Medications used for lowering cholesterol (Bile acid sequestrants)

Interaction Rating=Moderate Be cautious with this combination.

Some medication for lowering cholesterol called bile acid sequestrants can decrease how much niacin or niacinamide the body absorbs. This might reduce the effectiveness of niacin or niacinamide. Take niacin or niacinamide and the medications at least 4 hours apart.

Some of these medications used for high cholesterol include cholestyramine (Questran) and colestipol (Colestid).

Medications used for lowering cholesterol (Statins)

Interaction Rating=Moderate Be cautious with this combination.

Niacin can adversely affect the muscles. Some medications used for lowering cholesterol called statins can also affect the muscles. Taking niacin along with these medications for lowering cholesterol might increase the risk of muscle problems.

Some of these medications used for high cholesterol include rosuvastatin (Crestor), atorvastatin (Lipitor), lovastatin (Mevacor), pravastatin (Pravachol), and simvastatin (Zocor).

Nicotine patch (Transdermal nicotine)

Interaction Rating=Minor Be watchful with this combination.

Niacin can sometimes cause flushing and dizziness. The nicotine patch can also cause flushing and dizziness. Taking niacin and/or niacinamide (vitamin B3) and using a nicotine patch can increase the possibility of becoming flushed and dizzy.

Primidone (Mysoline)

Interaction Rating=Moderate Be cautious with this combination.

Primidone (Mysoline) is broken down by the body. There is some concern that niacinamide might decrease how fast the body breaks down primidone (Mysoline). But there is not enough information to know if this is important.

Probenecid

Interaction Rating=Moderate Be cautious with this combination.

Probenecid is used to treat gout. Taking large doses of niacin might worsen gout and decrease the effectiveness of probenecid.

Sulfinpyrazone (Anturane)

Interaction Rating=Moderate Be cautious with this combination.

Sulfinpyrazone (Anturane) is used to treat gout. Taking large doses of niacin might worsen gout and decrease the effectiveness of sulfinpyrazone (Anturane).

Are there any interactions with herbs and supplements?
Beta-carotene: A combination of niacin and the prescription drug simvastatin (Zocor) raises HDL (high density lipoprotein) cholesterol (“good cholesterol”) in people with coronary heart disease and low HDL levels. However, taking niacin along with combinations of antioxidants, including beta-carotene, seems to blunt this rise in HDL. It is not known whether this effect happens in people who don’t have coronary heart disease.
Chromium: Taking niacin and chromium together might lower blood sugar. If you have diabetes and take chromium and niacin supplements together, monitor your blood sugar to make sure it doesn’t get too low.
Herbs and supplements that might harm the liver: Niacin, especially in higher doses can cause liver damage. Taking niacin along with other herbs or supplements that might harm the liver could increase this risk. Some of these products include androstenedione, borage leaf, chaparral, comfrey, dehydroepiandrosterone (DHEA), germander, kava, pennyroyal oil, red yeast, and others.
Herbs and supplements that might lower blood pressure: Niacin might lower blood pressure. Taking niacin with other herbs and supplements that also lower blood pressure might cause blood pressure to drop too much. Other herbs and supplements that can lower blood pressure include andrographis, casein peptides, cat’s claw, coenzyme Q10, L-arginine, lycium, stinging nettle, theanine, and others.
Herbs and supplements that might slow blood clotting: Niacin might slow blood clotting. Using niacin along with other herbs and supplements that also slow blood clotting might increase the risk of bleeding in some people. Some other herbs of this type include angelica, clove, danshen, garlic, ginger, Panax ginseng, and others.
Kombucha tea: There is some concern that kombucha tea might decrease niacin absorption. However, this needs to be studied more.
Selenium: A combination of niacin and the prescription drug simvastatin (Zocor) raises HDL (high density lipoprotein) cholesterol (“good cholesterol”) in people with coronary heart disease and low HDL levels. However, taking niacin along with combinations of antioxidants, including selenium, seems to blunt this rise in HDL. It is not known whether this effect happens in people who don’t have coronary heart disease.
Tryptophan: Some tryptophan from the diet can be converted into niacin in the body. Taking niacin and tryptophan together might increase levels and side effects of niacin.
Vitamin C: A combination of niacin and the prescription drug simvastatin (Zocor) raises HDL (high density lipoprotein) cholesterol (“good cholesterol”) in people with coronary heart disease and low HDL levels. However, taking niacin along with combinations of antioxidants, including vitamin C, seems to blunt this rise in HDL. It is not known whether this effect happens in people who don’t have coronary heart disease.
Vitamin E: A combination of niacin and the prescription drug simvastatin (Zocor) raises HDL (high density lipoprotein) cholesterol (“good cholesterol”) in people with coronary heart disease and low HDL levels. However, taking niacin along with combinations of antioxidants, including vitamin E, seems to blunt this rise in HDL. It is not known whether this effect happens in people who don’t have coronary heart disease.
Zinc: The body can make niacin. People who are malnourished and have niacin deficiency, such as chronic alcoholics, make extra niacin if they take zinc. There might be an increased risk of niacin-related side effects such as flushing and itching if niacin and zinc are taken together.

Are there any interactions with food?
Hot drinks: Niacin can cause flushing and itching. These effects might be increased if niacin is taken with a hot drink.

What dose is used?
The following doses have been studied in scientific research:

ADULTS

BY MOUTH:

  • General: Some dietary supplement products list niacin on the label in niacin equivalents (NE). 1 mg of niacin is the same as 1 mg NE. When niacin is listed on a label as NE, it might include other forms of niacin as well, including niacinamide, inositol nicotinate, and tryptophan. The daily recommended dietary allowances (RDAs) for niacin in adults are 16 mg NE for men, 14 mg NE for women, 18 mg NE for pregnant women, and 17 mg NE for lactating women.
  • For high cholesterol:The effects of niacin are dose-dependent. Doses of niacin as low as 50 mg and as high as 12 grams each day have been used. However, the biggest increases in HDL and decreases in triglycerides occur at 1200 to 1500 mg/day. Niacin’s greatest effects on LDL occur at 2000 to 3000 mg/day. Niacin is often used with other medications for improving cholesterol levels.
  • For preventing and treating vitamin B3 deficiency and related conditions such as pellagra: 300-1000 mg daily in divided doses.
  • For treating hardening of the arteries: Doses of niacin have been as high as 12 grams daily. However, a dose of about 1 to 4 grams of niacin daily, alone or along with statins or bile acid sequestrants (a cholesterol-lowering medicine), has been used for up to 6.2 years.
  • For reducing fluid loss caused by cholera toxin: 2 grams daily has been used.
  • For abnormal blood fat levels due to treatment for HIV/AIDS: Up to 2 grams daily has been used.
  • For metabolic syndrome: 2 grams of niacin has been taken daily for 16 weeks. In some cases, niacin 2 grams daily, alone or at this dosage, is taken along with 4 grams of prescription omega-3 ethyl esters (Lovaza, GlaxoSmithKline Pharmaceuticals).

BY IV:

  • For preventing and treating vitamin B3 deficiency and related conditions such as pellagra: 60 mg of niacin has been used.

AS A SHOT:

  • For preventing and treating vitamin B3 deficiency and related conditions such as pellagra: 60 mg of niacin has been used.

CHILDREN

BY MOUTH:

  • General: The daily recommended dietary allowances (RDAs) for niacin in children are 2 mg NE for infants 0-6 months of age, 4 mg NE for infants 7-12 months of age, 6 mg NE for children 1-3 years of age, 8 mg NE for children 4-8 years of age, 12 mg NE for children 9-13 years of age, 16 mg NE for boys 14-18 years of age, and 14 mg NE for girls 14-18 years of age.
  • For preventing and treating vitamin B3 deficiency and related conditions such as pellagra: 100-300 mg per day of niacin, given in divided doses.

By what other names is the product known?
3-Pyridinecarboxylic Acid, Acide Nicotinique, Acide Pyridine-Carboxylique-3, Anti-Blacktongue Factor, Antipellagra Factor, B Complex Vitamin, Complexe de Vitamines B, Facteur Anti-Pellagre, Niacina, Niacine, Nicosedine, Nicotinic Acid, Pellagra Preventing Factor, Vitamin B3, Vitamin PP, Vitamina B3, Vitamine B3, Vitamine PP.

Natural Medicines disclaims any responsibility related to medical consequences of using any medical product. Effort is made to ensure that the information contained in this monograph is accurate at the time it was published. Consumers and medical professionals who consult this monograph are cautioned that any medical or product related decision is the sole responsibility of the consumer and/or the health care professional. A legal License Agreement sets limitations on downloading, storing, or printing content from this Database. Except for any possible exceptions written into your License Agreement, no reproduction of this monograph or any content from this Database is permitted without written permission from the publisher. Unlawful to download, store, or distribute content from this site.

For the latest comprehensive data on this and every other natural medicine, health professionals should consult the Professional Version of the Natural Medicines. It is fully referenced and updated daily.

© Copyright 1995-2021. Therapeutic Research Faculty, publishers of Natural Medicines, Prescriber’s Letter, and Pharmacist’s Letter. All rights reserved.