Niacin

Related Terms

• 2-pyridone, 3-pyridine carboxamide, acipimox (5-methylpyrazinecarboxylic acid 4-oxide), acipomox, Acipimox®, anti-blacktongue factor, antipellagra factor, B vitamin, B-complex vitamin, benicot, B-vitamin, chromium polynicotinate (niacin-bound chromium), coenzyme beta-nicotinamide adenine dinucleotide (NAD(+)), crystalline niacin, dihydropyridines, Efacin®, Endur-Acin® (sustained release niacin (nicotinic acid)), Enduramide®, ER niacin, esters of niacin, extended-release (ER) niacin, extended-release (ER) niacin monotherapy, extended-release (ER) niacin therapy, Hexopal®, immediate-release (crystalline) niacin, immediate-release niacin, inositol hexaniacinate, inositol hexanicotinate, inositol nicotinate, kynurenine (KYN), low-dose sustained-release nicotinic acid (Tri-B3), meso-inositol hexanicotinate, methyl niacinamide, Nature's Bounty® Flush Free Niacin Inositol Hexanicotinate 500mg Dietary Supplement, NIAC®, niacin, niacin (nicotinic acid), niacin equivalents, niacin ER, niacinamide, niacinamide adenine dinucleotide (NAD), niacinamide adenine dinucleotide phosphate (NADP), niacin/colestipol therapy, Niacor®, Niaspan® (prolonged-release nicotinic acid), Niaspan® (sustained-release nicotinic acid), Nicalex®, nicamid, Nicamin®, Nicangin®, Niceritrol, Nico-400®, Nicobid® (sustained-released niacin), Nicobid® (time-release niacin), Nicolar® (unmodified niacin), nicosedine, Nico-Span®, nicotinamide, nicotinamide (niacinamide), Nicotinamide cures, nicotinate, Nicotinex®, nicotinic acid, nicotinic acid adenine, nicotinic acid adenine dinucleotide phosphate (NAADP), nicotinic acid amide, nicotinic acid analog (low plasma free fatty acid trial, LFA), nicotinic acid analogue, nicotinic amide, nicotinuric acid, nicotylamidum, nutrient supplements, Papulex®, pellagra preventing factor, pentaerythritoltetranicotinate, perycit, prolonged-release (PR) nicotinic acid (niacine)[Niaspan®], pyridine-3-carboxylic acid, Slo-Niacin® (sustained-release niacin), sustained-release nicotinic acid (Nico-Span®), Tega-Span®, Tri-B3®, trigonelline, tryptophan, vitamin B-3, vitamin B3, vitamin B3 (nicotinamide), vitamin B3 derivative, vitamin-B complex (vit-B), Wampocap®, wax-matrix sustained release niacin, wax-matrix sustained-release niacin (Endur-Acin®).

Background

• Vitamin B3 is made up of niacin (nicotinic acid) and its amide, niacinamide, and can be found in many foods, including yeast, meat, fish, milk, eggs, green vegetables, and cereal grains. Dietary tryptophan is also converted to niacin in the body. Vitamin B3 is often found in combination with other B vitamins including thiamine, riboflavin, pantothenic acid, pyridoxine, cyanocobalamin, and folic acid.

Evidence

*Key to grades:

A: Strong scientific evidence for this use;
B: Good scientific evidence for this use;
C: Unclear scientific evidence for this use;
D: Fair scientific evidence against this use (it may not work);
F: Strong scientific evidence against this use (it likely does not work).

For full grading rationale, click here.

Safety

The U.S. Food and Drug Administration does not strictly regulate herbs and supplements. There is no guarantee of strength, purity or safety of products, and effects may vary. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare professional before starting a new therapy. Consult a healthcare professional immediately if you experience side effects.

Allergies

• Rarely, anaphylactic shock (severe allergic reaction) has been described after intravenous or oral niacin therapy.

Side Effects and Warnings

• Most people taking niacin experience skin flushing and a warm sensation, especially of the face, neck, and ears when they begin treatment or increase dose. This reaction is usually mild, but has been intolerable enough to cause up to half of participants in studies to stop therapy. Dry skin and itching is also commonly experienced. Taking aspirin or non-steroidal anti-inflammatory drugs such as ibuprofen (Advil®, Motrin®), naproxen (Naprosyn®), or indomethacin (Indocin®) can reduce the flushing. Use of an antihistamine 15 minutes prior to a niacin dose may also be helpful. Slow-release niacin products may have less skin flushing than regular release niacin preparations or may simply delay the appearance of flushing. The flushing response often decreases on its own after one to two weeks of therapy. Mild stomach upset, nausea, vomiting, and diarrhea also may occur when beginning niacin therapy; these symptoms usually resolve with continued use.
• More serious side effects include liver toxicity, worsening of stomach ulcers, and altered blood sugar or insulin levels or uric acid concentrations. Numerous case reports describe liver toxicity, including increased liver enzyme levels in the blood, skin yellowing (jaundice), fluid in the abdomen (ascites), or liver failure. Monitoring of liver blood tests while using niacin is recommended. While slow-release niacin products may have less skin flushing than regular release niacin preparations, they may worsen stomach and liver side effects. High doses of niacin may also cause low blood pressure.
• Lactic acidosis, muscle cell damage (myopathy), and increased blood levels of creatine kinase (a marker of muscle damage) have been reported in studies.
• Abnormal heart rhythms, heart palpitations, and circulatory collapse (when injected through the veins) have occurred following niacin use. Based on human research, taking niacin alone or with colestipol may increase blood homocysteine levels. High levels of homocysteine have been associated with an increased risk of heart disease.
• Blood clotting problems have been reported during treatment with sustained-release niacin. Low white blood cell number (leukopenia) and slightly increased blood eosinophils have also been reported.
• Rarely reported side effects include headache, dry eye, tooth or gum pain, dizziness, breathing difficulty, increased anxiety, panic attacks, rash, and decreased thyroid function (hypothyroidism). There are published accounts of temporary side effects of the eye including macular swelling and blurred vision as well as toxic amblyopia ("lazy eye"). These side effects resolved when niacin was stopped.

Pregnancy and Breastfeeding

• Use of niacin supplementation during pregnancy or breastfeeding is not recommended due to lack of sufficient research of safety and effectiveness.

Interactions

Most herbs and supplements have not been thoroughly tested for interactions with other herbs, supplements, drugs, or foods. The interactions listed below are based on reports in scientific publications, laboratory experiments, or traditional use. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare professional before starting a new therapy.

Interactions with Drugs

• In theory, there may be an increased risk of liver damage if niacin is taken with alcohol or drugs that are toxic to the liver. Niacin-induced flushing may be increased by simultaneous use of alcohol and nicotine.
• Based on human study, use of niacin with cholesterol-lowering drugs, such as "statins" (HMG-CoA reductase inhibitors) including lovastatin (Mevacor®) or atorvastatin (Lipitor®), bile acid sequestrants like cholestyramine, probucol, or anti-lipid agents like gemfibrozil may result in further reductions in cholesterol than caused by either agent alone. However, bile acid sequestrants cholestyramine and colestipol may reduce niacin absorption into the body. Use of niacin with HMG-CoA reductase inhibitors or gemfibrozil may increase the risk of serious side effects such as liver or muscle damage. Although not well studied in humans, niacin may also interact with procetofene, another cholesterol-lowering drug.
• Based on human study, niacin may increase blood sugar levels, and may require dosing adjustments of insulin or prescription diabetes drugs. Caution is advised when using medications that may affect blood sugar.
• Antibiotics can lead to decreased amounts of B vitamins in the body. Conversely, based on animal study, pyrazinamide may increase niacin levels. Use of niacin with neomycin may add to the cholesterol-lowering effects of niacin. Based on laboratory study, niacinamide may interact with the antifungal drug griseofulvin (increases its solubility), with possible effects on its activity.
• In theory, niacin therapy may increase the risk of bleeding. There are published case reports of patients who developed reversible abnormal blood clotting (coagulopathy) conditions while taking sustained-release niacin. In addition, low blood platelet number (thrombocytopenia) has been observed in studies of niacin therapy. Some examples of drugs that may increase the risk of bleeding if taken with niacin include aspirin and anticoagulants ("blood thinners") such as warfarin (Coumadin®).
• Based on animal research, use of niacinamide with seizure medications like diazepam (Valium®), carbamazepine (Tegretol®), or sodium valproate (Depakote®) may increase their anti-seizure action. In laboratory studies, niacinamide has interacted with diazepam (increases its solubility) with uncertain overall effects. If taken with blood pressure-lowering drugs, niacinamide may cause a greater lowering of blood pressure. Niacin may interact with ganglionic blocking agents and increase the risk of lightheadedness and low blood pressure in some people when they stand up.
• Based on human study, niacin may alter thyroid hormones and require dosing adjustment of thyroid medications. Based on laboratory research, niacinamide may interact with testosterone, estrogen, or progesterone. Use of birth control pills may increase the amount of niacin produced in the body, thus lowering the doses of niacin needed for treatment.
• Because niacin may alter blood flow in age-related macular degeneration (AMD), patients using drugs or supplements to treat AMD should use niacin cautiously. Niacin may interact with agents that cause the veins in the body to dilate or enlarge.
• Niacin may interact with certain agents that are broken down in the liver by the cytochrome P450 system. Check with a pharmacist for a complete list of possible interactions.

Interactions with Herbs and Dietary Supplements

• In theory, use of niacin or niacinamide with herbs or supplements that have potential to cause liver injury may cause greater risk of liver toxicity.
• Use of aspirin has been shown to reduce the tingling, itching, flushing, and warmth associated with oral niacin administration, an effect which may also result from the use of possible salicylate-containing herbs like black cohosh, meadowsweet, poplar, sweet birch, willow bark, and wintergreen. However, levels of salicylates in herbs may vary or be too low to have this desired effect.
• Niacin may add to the effects of herbs that may lower blood cholesterol levels, including fish oil, garlic, or guggul. Based on human study, taking such combinations as chromium polynicotinate (niacin-bound chromium) with grape seed proanthocyanidin, or niacin with β-sitosterol and dihydro-β-sitosterol, may result in greater improvements in cholesterol than either agent alone.
• Antioxidants may reduce niacin's beneficial effects on cholesterol levels and heart disease, possibly by interfering with niacin's effects on high-density cholesterol (HDL). Recent research suggests that the addition of antioxidants to a combination of niacin plus simvastatin (Zocor®) reduced the benefit of niacin on heart blood vessel plaques, suggesting possible interference by antioxidants. In other research, use of niacin with vitamin A and vitamin E had greater effects on cholesterol levels than niacin alone. Vitamin E in combination with colestipol and niacin has also been associated with greater benefits on heart blood vessel plaques. This remains an area of controversy.
• Based on human study, niacin may increase blood sugar levels and may require dosing adjustments of hypoglycemic agents. In children, use of niacinamide and insulin together has been shown to lead to a reduction in insulin dosage in patients with type 1 diabetes mellitus. Caution is advised when using herbs or supplements that may affect blood sugar.
• In theory, niacin therapy may increase the risk of bleeding when taken with herbs and supplements that are believed to increase the risk of bleeding. There are published case reports of patients who developed reversible abnormal blood clotting (coagulopathy) conditions while taking sustained-release niacin. In addition, low blood platelet number (thrombocytopenia) has been observed in studies of niacin therapy. Multiple cases of bleeding have been reported with the use of Ginkgo biloba, and fewer cases with garlic or saw palmetto.
• Based on laboratory study, niacinamide may interact with herbs or supplements with estrogen-like properties, and theoretically may increase the amount of niacin produced in the body (thus lowering the doses of niacin needed for treatment).
• Based on human study, niacin may interact with thyroid-active herbs or supplements such as bladderwrack, and alter thyroid hormone blood tests. Preliminary human research reports that zinc sulfate increases the amount of niacin breakdown products in the urine, suggesting a possible interaction between the two agents.
• Because niacin may alter blood flow in age-related macular degeneration (AMD), patients using herbs or supplements to treat AMD should use niacin cautiously. Niacin may interact with herbs or supplements that cause the veins in the body to dilate or enlarge.
• Niacin may interact with certain agents that are broken down in the liver by the cytochrome P450 system. Check with a pharmacist for a complete list of possible interactions.

Authors

• This information is based on a professional level monograph edited and peer-reviewed by contributors to the Natural Standard Research Collaboration (www.naturalstandard.com).

Selected References

Natural Standard developed the above evidence-based information based on a systematic review of the available scientific articles. For comprehensive information about alternative and complementary therapies on the professional level, go to www.naturalstandard.com. Selected references are listed below.

1. Birjmohun RS, Hutten BA, Kastelein JJ, et al. Efficacy and safety of high-density lipoprotein cholesterol-increasing compounds: a meta-analysis of randomized controlled trials. J Am Coll Cardiol 2005;45(2):185-197.
2. Bissett DL, Oblong JE, Berge CA. Niacinamide: A B vitamin that improves aging facial skin appearance. Dermatol Surg 2005 Jul;31(7 Pt 2):860-5; discussion 865.
3. Brown BG, Zhao XQ, Chait A, et al. Simvastatin and niacin, antioxidant vitamins, or the combination for the prevention of coronary disease. N Engl J Med 2001;345(22):1583-1592.
4. Dube MP, Wu JW, Aberg JA, et al. Safety and efficacy of extended-release niacin for the treatment of dyslipidaemia in patients with HIV infection: AIDS Clinical Trials Group Study A5148. Antivir Ther 2006;11(8):1081-1089.
5. Gerber MT, Mondy KE, Yarasheski KE, et al. Niacin in HIV-infected individuals with hyperlipidemia receiving potent antiretroviral therapy. Clin Infect Dis 2004;39(3):419-425.
6. Grundy SM, Vega GL, McGovern ME, et al. Efficacy, safety, and tolerability of once-daily niacin for the treatment of dyslipidemia associated with type 2 diabetes: results of the assessment of diabetes control and evaluation of the efficacy of niaspan trial. Arch Intern Med 2002;162(14):1568-1576.
7. Kashyap ML, McGovern ME, Berra K, et al. Long-term safety and efficacy of a once-daily niacin/lovastatin formulation for patients with dyslipidemia. Am J Cardiol 2002;89(6):672-678.
8. McKenney JM, Jones PH, Bays HE, et al. Comparative effects on lipid levels of combination therapy with a statin and extended-release niacin or ezetimibe versus a statin alone (the COMPELL study). Atherosclerosis 2007;192(2):432-437.
9. Metelitsina TI, Grunwald JE, DuPont JC, et al. Effect of niacin on the choroidal circulation of patients with age related macular degeneration. Br J Ophthalmol 2004;88(12):1568-1572.
10. Qu CX, Kamangar F, Fan JH, et al. Chemoprevention of primary liver cancer: a randomized, double-blind trial in Linxian, China. J Natl Cancer Inst 2007 Aug 15;99(16):1240-7.
11. Rubenfire M. Safety and compliance with once-daily niacin extended-release/lovastatin as initial therapy in the Impact of Medical Subspecialty on Patient Compliance to Treatment (IMPACT) study. Am J Cardiol 2004;94(3):306-311.
12. Studer M, Briel M, Leimenstoll B, et al. Effect of different antilipidemic agents and diets on mortality: a systematic review. Arch Intern Med 2005;165(7):725-730.
13. Veverka A, Jolly JL. Recent advances in the secondary prevention of coronary heart disease. Expert Rev Cardiovasc Ther 2004;2(6):877-889.
14. Whitney EJ, Krasuski RA, Personius BE, et al. A randomized trial of a strategy for increasing high-density lipoprotein cholesterol levels: effects on progression of coronary heart disease and clinical events. Ann Intern Med 2005;142(2):95-104.
15. Wink J, Giacoppe G, King J. Effect of very-low--dose niacin on high-density lipoprotein in patients undergoing long-term statin therapy. Am Heart J 2002;143(3):514-518.

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