Blood red, painful, burning, skin.blurry eye sight, vomiting, extreme head ache.are these severe symptoms of a reaction from niacin?how long will it last?

Not usually: You sound ill. If it just started all of a sudden go to urgent care or er, and i rarely give that advice!

Possibly: Niacin commonly causes flushing (hot feeling, red skin, tingling) and headaches after taking, particularly doses greater than 1000 mg. The best thing to do is stop taking it for a couple days to see if the symptoms go away. Hope this helps.