Niacin, also called nicotinic acid or B3, was one of the first medications used to treat people with abnormal lipid levels. It raises high-density lipoprotein levels, but also lowers high levels of low-density lipoprotein and high triglyceride levels. Niacin does, however, have side effects.
Flushing
Patients may experience flushing and itching on the face, chest, stomach and back. The flushing is usually worse when niacin is first started; if the dosage is increased, or if taken with alcoholic drinks and hot beverages. It usually stops one to two weeks after the patient has been taking the same dose, according to Robert Mahley, M.D., Ph.D., Director of the Gladstone Institute of Cardiovascular Disease in "Goodman & Gilman's The Pharmacological Basis of Therapeutics." Flushing may stop if aspirin is taken every day. Less flushing may occur if the patient starts niacin at a low dose or takes it after breakfast or dinner.
Liver Toxicity
Liver toxicity is the most serious side effect of niacin. Dr. Mahley writes that there have been reports that the regular niacin and the sustained-release niacin can cause liver toxicity. People may develop liver abnormalities if over two grams of the sustained-release over-the-counter medication is taken. They will also feel tired and weak as though they have the flu. Lab results show increased liver enzyme levels and decreased albumin protein in the bloodstream, both signs of damage to the liver. The extended-release niacin does not seem to cause as many cases of liver toxicity.
High Blood Glucose Levels
The beta cells of the pancreas secrete insulin to prevent high glucose levels in the bloodstream. People with diabetes mellitus type 2 have tissues and organs that are not as sensitive to insulin as they should be. As a result, they have high blood glucose levels. Dr. Mahley writes about a study in "Goodman & Gilman's The Pharmacological Basis of Therapeutics," where four percent of people with diabetes type 2 stopped taking the extended-release niacin because they could not control their blood glucose levels. He writes that niacin can cause a resistance to insulin, and its use in those with diabetes should include checking their blood glucose levels every week until the glucose levels are stable. Many diabetics have to start taking insulin if they take niacin.
Other Side Effects
Some develop rashes and dry skin, while others develop a condition called acanthosis nigricans, or a dark velvety pigmentation on their neck or underarms. Some get an upset stomach, become nauseous, vomit and have diarrhea. This occurs less if they take niacin after eating. Anyone who has had peptic ulcers should not take niacin to treat abnormal lipid levels, because it can reactivate their ulcers. Patients who has had gout should not take niacin because it increases the uric acid levels and reactivates gout. Pregnant women should not take niacin to treat abnormal lipids because it has been shown to cause birth defects in animals when given in very high doses. Rarely, niacin can cause heart and eye abnormalities, writes Mary Molloy, M.D, Clinical Professor of Medicine in the Department of Medicine at the University of California in "Basic & Clinical Pharmacology."
References
- "Basic & Clinical Pharmacology"; Bertram Katzung, M.D., Ph.D., Susan Masters, Ph.D., Anthony Trevor, Ph.D.; 2009
- "Goodman & Gilman's The Pharmacological Basis of Therapeutics"; Laurence Brunton, Ph.D.; 2006
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