I have been using this product for a year after switching from GNC's niacin (B3). GNC's product was good, but very expensive. I no longer experience the 'Niacin Flush' that people are complaining about. Before taking any megadose supplement/vitamin, you should CONSULT YOUR DOCTOR. Taking large doses of vitamin B3 (niacin) requires you to have good liver function. If your liver function is poor, you could permanently damage it. My doctor specifically told me to STAY AWAY FROM THE ''NO-FLUSH'' NIACINAMIDE. I hope this review helps some people to realize that taking megadoses of niacin should be taken with an informed consent, and the green light from your doctor. . . . . I use only products that have Scientifically Proven benefits.