Abstracts

BACKGROUND: Niacin is widely available over the counter (OTC). We sought to determine the safety of 500 mg immediate release niacin, when healthy individuals use them as directed. METHODS: 51 female and 17 male healthy volunteers (mean age 27 years SD 4.4) participated in a randomized placebo-controlled blinded trial of a single dose of an OTC, immediate-release niacin 500 mg (n = 33), or a single dose of placebo (n = 35) on an empty stomach. The outcomes measured were self-reported incidence of flushing and other adverse effects. RESULTS: 33 volunteers on niacin (100%) and 1 volunteer on placebo (3%) flushed (relative risk 35, 95% confidence interval (CI) 6.8-194.7). Mean time to flushing on niacin was 18.2 min (95% CI: 12.7-23.6); mean duration of flushing was 75.4 min (95% CI: 62.5-88.2). Other adverse effects occurred commonly in the niacin group: chills (51.5% vs. 0%, P