Niacin Flush
Harmless skin flushing from niacin; caused by prostaglandin release via GPR109A; indicates niacin activity.
The niacin flush is a common side effect of nicotinic acid (niacin) supplementation, characterized by warmth, redness, and tingling of the skin, particularly the face, neck, and upper body. It occurs because niacin activates the GPR109A receptor on skin Langerhans cells, triggering prostaglandin D2 release which causes vasodilation.
The flush typically begins 20-30 minutes after taking niacin and subsides within 1-2 hours. While uncomfortable, it is harmless and often diminishes with continued use (tachyphylaxis). Strategies to reduce flush: take with food, start with low doses and increase gradually, use extended-release formulations, or take aspirin 30 minutes before (blocks prostaglandin synthesis).
Niacinamide does not cause flush because it doesn't activate GPR109A, but it also lacks some of niacin's lipid benefits.
Metabolic Connections
Niacin Flush connects to 3 other pathways.
