Hi Dawn...
Yep i had this!
When i first started to supplement in advance of amalgam removal, i took all my vitamins at the same time so didnt know it was B3.
I thought it was the high dose Vit C actually [this does cause me a little bit of heat / itchiness/ irritability].
But as i discovered, B3 alone brings on an intense heat and flushing of upper body within 20/30 mins of taking it.
My arms were almost purple... lol <img src="/ubbthreads/images/graemlins/blush.gif" alt="" /> It faded soon enough though.

Take care
V