Niacin (nicotinic acid) is used to prevent and treat niacin deficiency (pellagra). Niacin deficiency may result from certain medical conditions (such as alcohol abuse, malabsorption syndrome, Hartnup disease), poor diet, or long-term use of certain medications (such as isoniazid).
Niacin deficiency can cause diarrhea, confusion (dementia), tongue redness/swelling, and peeling red skin. Niacin is also known as vitamin B3, one of the B-complex vitamins. Vitamins help to support the body’s ability to make and break down natural compounds (metabolism) needed for good health. Niacinamide (nicotinamide) is a different form of vitamin B3 and does not work the same as niacin. Do not substitute unless directed by your doctor.
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Flushing/warmth in the face and neck, headache, itching, burning, sweating, chills, or tingling may occur within 20 minutes to 4 hours of taking this medication. Flushing may persist for a few hours. These effects should improve or go away as your body adjusts to the medication. Stomach upset, heartburn, nausea, vomiting, and diarrhea may also occur. If any of these effects persist or worsen, tell your doctor or pharmacist promptly.
Take this medication by mouth with a low-fat meal or snack as directed by your doctor, usually 1-3 times daily. Taking niacin on an empty stomach increases side effects (such as flushing, upset stomach). Follow all directions on the product package. If your doctor has prescribed this medication, take it as directed. If you are uncertain about any of the information, consult your doctor or pharmacist. Niacin is available in different formulations (such as immediate and sustained release). Do not switch between strengths, brands, or forms of niacin. Severe liver problems may occur. Swallow extended-release capsules whole. Do not crush or chew extended-release capsules or tablets. Doing so can release all of the drug at once, increasing the risk of side effects. Also, do not split extended-release tablets unless they have a score line and your doctor or pharmacist tells you to do so. Swallow the whole or split tablet without crushing or chewing. To lessen the chance of side effects such as flushing, avoid alcohol, hot beverages, and eating spicy foods near the time you take niacin. Taking a plain (non-enteric coated, 325 milligram) aspirin or a nonsteroidal anti-inflammatory drug (such as ibuprofen, 200 milligrams) 30 minutes before taking niacin may help prevent flushing. Ask your doctor if this treatment is right for you.