I think what I just experienced was a niacin flush, but it was the worst I have ever had. I took a B-right, it has 25mg of niacin. About 45 min. to an hour later I got a bad pain in my stomach then it moved up to my chest. Next thing my skin started to burn and itch and I looked like I had a blotchy sunburn. I've had this before but never with stomach pain. Also my face swelled a little. Could this small amount of niacin cause this effect?