Both niacin and niacinamide, two forms of vitamin B3, can produce flulike symptoms. Niacin, sometimes prescribed to treat high cholesterol, causes more dramatic symptoms than niacinamide, prescribed for Type 1 diabetes. As your body adjusts to the medication, the flulike symptoms will likely disappear. But, if you take either type of niacin for a long time, you may face far more serious side effects. You need a prescription for niacin, but you should also consult a doctor before taking niacinamide.
Dose and Symptoms
If you take more than 50 mg of niacin or niacinamide a day, you may suffer stomach upset, nausea and dizziness. You may also experience skin flushes -- your face, chest and, sometimes, your arms turn red and your skin itches, burns and tingles. Skin flushes occur more commonly while taking niacin than niacinamide. Both niacin and niacinamide may worsen allergies because they release histamines. Niacinamide, an over-the-counter supplement, comes in doses of 250 mg to 500 mg. Prescription niacin comes in doses of up to 3,000 mg -- 3 g. To avoid flulike symptoms, begin with a small dose and gradually increase the amount. It may also help to take an aspirin 30 minutes before your dose.
Skin Flushes
Niacin in high doses can help reduce low-density lipoprotein, referred to as LDL or "bad" cholesterol, and triglycerides, another type of fat in your bloodstream. It can also help elevate your high-density lipoprotein, LDL or the "good" cholesterol, that helps remove LDL cholesterol and triglycerides from your bloodstream. If you take niacin to improve your cholesterol or to alleviate atherosclerosis -- hardening of the arteries, do not switch to niacinamide to alleviate skin flushes and other flulike symptoms. Niacinamide, sometimes marketed as no-flush niacin, does not improve your blood lipid levels.
Side Effects
Both niacin and niacinamide can cause serious side effects with long-term use. These include irregular heartbeat, stomach ulcers, loss of vision, high blood sugar and liver damage. If you have gout, kidney disease, Type 2 diabetes or liver disease, you should not take any form of niacin without a doctor's consent and supervision. Niacin increases your levels of homocysteine, an amino acid that may increase your risk of heart disease.
Niacin Study
Niacin increased stroke risk among participants in a United States government study. The National Institutes of Health halted a planned five-year study 18 months prematurely because of disappointing results and safety concerns. Persons in the study who took 2,000 mg of niacin plus statins, another cholesterol-lowering drug, realized greater improvements in their cholesterol levels than participants who took only statins. But niacin users suffered more than twice as many strokes as nonusers. Niacin also failed to protect against heart attacks. The study ended in May 2011.
References
- University of Maryland Medical Center; Vitamin B 3 (Niacin); June 18, 2009
- Medline Plus: Niacin and Niacinamide (Vitamin B3)
- National Institutes of Health: NIH Halts Clinical Trial on Combination Cholesterol Treatment; May 26, 2011
- CBC News; Niacin Trial for Heart Disease Stopped Early; May 27, 2011
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