TL;DR Niacin, also known as vitamin B3, is an essential nutrient that can cause a temporary skin reaction called the "niacin flush." This harmless response—characterized by redness, warmth, tingling, or mild itching—occurs when blood vessels expand after taking niacin, especially in higher doses or on an empty stomach. While some people find it uncomfortable, niacin flush is actually a sign of healthy circulation and a key benefit of this nutrient. To reduce flushing, take niacin with food…
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