Niacin (nicotinic acid) can cause skin flushing and tingling (the "niacin flush"). This is not a bad or dangerous thing, but rather can be unpleasant for some. Levels as low as 20mg can lead some people to flush, so it is best to build up to the dose within this capsule (250mg) especially when taken away from food. One becomes accustomed to the flushing and it then takes higher doses to elicit this reaction
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