Why do i get an itchy red flushing rash when i get hot or am in a hot environment for even short (less than 30) periods of time. what could cause this?? allergy meds (benadryl and vistaril) stop the itching but i still have red and hot skin for hours

Where?: If the rash is confined to your face or neck, it may be from rosacea. If it is generalized, then cholinergic urticaria ( when small hives develop after activities which leads to an increase in core body temperature) would be the likely cause. Try doubling up your antihistamine to see if it works any better. See allergist if problem remains bothersome.

Cholinergic hives: You could be suffering from cholinergic urticaria (hives) as your condition seems to be somewhat responsive to antihistamines. I would recommend seeing an Allergist for further workup and evaluation. Sometimes higher-dose daily antihistamines are warranted with this condition.