Does Niacor (niacin, or nicotinic acid, vitamin B3) cause side effects?

Niacor (niacin, or nicotinic acid, vitamin B3) is a vitamin that is part of a normal diet and is essential to various chemical reactions in the body. Niacor is used medically to treat individuals with deficiency of niacin. 

Advanced deficiency of niacin can lead to a condition called pellagra in which individuals develop diarrhea, inflammation of the skin (dermatitis), and dementia.

Niacor also is used to reduce cholesterol and triglyceride levels in the blood. Specifically, it reduces bad cholesterol (LDL cholesterol) and increases good cholesterol (HDL cholesterol). 

It is not clear how niacin causes its effects on cholesterol and triglyceride levels, but it may be by reducing the production of proteins that transport cholesterol and triglycerides in the blood. Natural sources of niacin include meat, poultry, liver, fish, nuts, green vegetables, whole grains, and potatoes. 

Common side effects of Niacor include

Serious side effects of Niacor include rare cases of liver failure or muscle injury. 

Drug interactions of Niacor include drugs that cause liver or muscle injury, such as lovastatin or simvastatin, which may increase the occurrence of liver or muscle injury. 

Niacor may increase blood glucose levels in individuals with diabetes and medications for controlling blood glucose may need to be adjusted when niacin is taken by those with diabetes

Bile acid sequestrants bind and prevent absorption of Niacor. Administration of bile acid sequestrants and Niacor should be separated by 4-6 hours. 

It is unknown if the high doses of niacin used in treating elevated cholesterol levels are harmful to a fetus during pregnancy

Niacor is actively secreted in breast milk. Nursing mothers taking Niacor should avoid breastfeeding or discontinue Niacor in order to prevent the newborn from ingesting large amounts of niacin.

What are the important side effects of Niacor (niacin, or nicotinic acid, vitamin B3)?

The most common side effects of niacin are:

Flushing may be reduced by taking 325 mg of aspirin 30 minutes before the niacin and by increasing the dose of niacin slowly. Drinking hot liquids or alcohol shortly before or after niacin is taken may increase the occurrence of flushing. Extended release formulations of niacin may cause flushing less frequently than immediate release formulations.

Rare cases of liver failure or muscle injury have occurred from the use of niacin. Blood tests to monitor for liver injury should be performed before niacin therapy begins, every 6-12 weeks for the first year, and then occasionally thereafter.

Niacin should be discontinued if liver tests are greater than three times the upper limit of normal, are persistently elevated, or are accompanied by nausea, vomiting, or weakness.

Niacor (niacin, or nicotinic acid, vitamin B3) side effects list for healthcare professionals

Cardiovascular: Atrial fibrillation and other cardiac arrhythmias, orthostasis, hypotension.

Gastrointestinal: Dyspepsia, vomiting, diarrhea, peptic ulceration, jaundice, abnormal liver function tests. Skin: Mild to severe cutaneous flushing, pruritus, hyperpigmentation, acanthosis nigricans, dry skin. Metabolic: Decreased glucose tolerance, hyperuricemia, gout.

Eye: Toxic amblyopia, cystoid macular edema.

Nervous System/Psychiatric: Headache.

What drugs interact with Niacor (niacin, or nicotinic acid, vitamin B3)?

HMG-CoA Reductase Inhibitors: See prescribing information for skeletal muscle warnings.

Antihypertensive Therapy: Nicotinic acid may potentiate the effects of ganglionic blocking agents and vasoactive drugs resulting in postural hypotension.

Aspirin: Concomitant aspirin may decrease the metabolic clearance of nicotinic acid. The clinical relevance of this finding is unclear.

Other: Concomitant alcohol or hot drinks may increase the side effects of flushing and pruritus and should be avoided at the time of drug ingestion.

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Medically Reviewed on 8/25/2020
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Professional side effects and drug interactions sections courtesy of the U.S. Food and Drug Administration.