allergy to heat

For the past four years or so, I break out in hives wherever heat touches me.  I cannot take a hot shower or bath or I break out.  I even break out sometimes with a warm shower.  Now if I reach in the oven or cook over a grill, wherever the heat touches my skin reaches my bare skin that area becomes very red and raised.  I often develop hives.  It really itches!!!!!  It can be relieved by benadryl, but it is very difficult to avoid heat altogether living in the south.  I cannot let a heating pad or anything that is hot touch my skin.  In fact, in the summer time when the steering wheel is hot the palms of my hands will get really red and itch like crazy.  Can you really be allergic to heat?

[National Jewish Health]

Yes, there is an entity called localized heat urticaria, commonly called hives, heat being one of several physical causes of hives.

Physical urticarias are a unique subgroup of chronic urticaria in which people develop urticaria due to environmental stimuli.  Common triggers include exercise, temperature changes, cold, heat, pressure, sunlight, vibration, and water.  Systemic symptoms have occurred during severe episodes.  Physical urticarias are responsible for approximately 20% to 30% of all cases of chronic urticaria.

It was reported in June 2001 in the Journal of Dermatological Science volume 26 number 2 pages 112-118 that therapy with antihistamines and repeated heat exposure to laser doppler flowmetry (LDF) might reduce one’s sensitivity to heat.  I could find no more recent report on this or other therapy and, so, would strongly suggest that you consult with a university medical center-associated dermatologist, ideally a doctor with a special interest in urticaria, regarding possible desensitization techniques.  In the meantime you and your doctor might want to initiate therapy with one of the non-sedating anti-histamines.

Good luck.