Niacin will ALWAYS cause a flush if you take enough of it — usually somewhere into the hundreds of milligrams (although occasionally people will flush on as little as 25 mgs). read more
Niacin and Burning Niacin does not actually cause burning of your skin, but you might develop a burning sensation after taking niacin supplements. This is actually a result of blood vessels in your body dilating, causing flushing that might manifest as a burning sensation on your skin. read more
Do not panic if you turn red or your heart beats rapidly when you take pure niacin because this is a good sign that your blood is pure and toxins are being removed. Some people take as much as 500-mg. niacin three times a day until they break through their toxins and feel a burn. read more