It said temporary flushing is from NIACIN. It was 500 mg pure NIACIN from GNC. My neck, my arms, my legs, my chest and stomach turned on fire, prickly, itched and were horrendous 3 minutes after I took the pill and lasted about a half hour. Was that the normal flushing reaction from this? Or did I have an allergic reaction? It is gone now. I was reading and it said that is normal it was a good sign that that happened or something. I took it to see if it helps circulate blood lowers my blood pressure and can help with my lightheaded feeling. I am afraid to take it again though. Maybe chop the pill in half and take 250 mg of it? Anyone have a clue?