Histamine reaction to heat?

Whenever my body gets hot, from working out, being out in the sun, hot showers, saunas...etc, I break out in little red splotches all over my torso, back, and neck. They are not hives and are not bumpy at all. I have also noticed it whenever I go to the beach. They are painless and sometimes a lite itchy. I don't know what causes this or what it even is! It's been going on since around elementary school. Is this an allergy or my body's defense against heat? Is there any treatment besides an antihistamine?

[Bhupinder Kaur, MD]

Hello,
One possibility for these symptoms of breaking out in red spots when the body is heated is cholinergic urticaria. It is a skin rash brought on by a hypersensitive reaction to body heat. To prevent it wear light breathable clothing allowing the body to remain cool. Take some antihistaminic like Benadryl or Claritin and apply some calamine lotion. If the symptoms persist then please get it examined from a dermatologist.

It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your doctor. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.