(lb)
niacin opens capillaries and clears arterial plaque for more blood flow, so you can get a flush when you're getting more blood flow to the tiny capillaries which feels like heat or needles and pins depending on how big of a flush. You can buffer the flush effect by taking the niacin on a full stomach. Or you can take the non flushing version of niacin called niacinamide. It doesn't have the same level of cardiac benefits as niacin does, hence no flush, but there's so many incredible benefits to taking B-3 (niacin/niacinamide) that cardiac is not the biggest reason for use. orthomolecular.org has archives of medical papers on b-3 therapy from curing or relieving schizophrenia and all varieties of mental disorders as well as alcoholism and drug addiction and smoking cessation and much more.