niacin, or vitamin B3, occurs naturally in a variety of foods, including tuna and peanuts. You can also take niacin supplements, by prescription or over the counter, to treat conditions such as high cholesterol, arthritis and atherosclerosis (hardening of the arteries). Niacin in your diet will unlikely cause side effects. But if you take niacin supplements in large quantities, side effects, including gout, may occur.
Niacin commonly causes skin flushes, a condition that makes your face and chest redden, itch, tingle and burn. Skin flushes, uncomfortable but not serious, give you an early warning sign of toxicity. If you lower your dose of niacin and gradually increase it, you may alleviate skin flushes. If your body, including your kidneys, can slowly adjust to higher amounts of niacin in your system, you may prevent gout. Other serious side effects of taking niacin include stomach ulcers and liver damage. The National Institutes of Health halted a niacin study in May 2011, 18 months earlier than planned, after participants who took 2,000 mg of niacin daily suffered twice as many strokes as study participants who did not take niacin.