heat induced hives

hello.  I have been getting hives when I get hot/sweat.  If I'm stuck in a warm place for awhile, i will start to get ichy and then hives will show up usually around my bra area. It is worse when I exercise, I get hives all over my body. I don't have a hard time breathing though.  This started sometime this winter.

I can't think of anything that I've changed. still use the same laundry soap, dish soap, shampoo, body wash, lotion, cleaning products.  I haven't eaten anything new.

My dr says that I have heat induced hives and put me on 24 Zyrtec and 25mg of Benedryl. It worked for about a month and now I'm breaking out in hives again when I exercise.  

I haven't had any allergy tests done yet.

A fitness friend of mine thinks that I might have a build up of toxins and when i sweat the toxins are being released. I haven't talked with my dr about that yet.  Is there any truth to this?  I do drink a good bit of regular soda.

Thanks everyone

[Dr Rajput]

Hi, welcome to the forum, your symptoms are suggestive of cholinergic urticaria. Cholinergic urticaria is a subcategory of physical urticaria that is a skin rash brought on by a hypersensitive reaction to body heat. Symptoms follow any stimulus to sweat such as exercise (sometimes called exercise-induced urticaria), heat from the sun (which could also indicate solar urticaria), saunas, hot showers (reaction to water can also indicate water urticaria), spicy foods which may cause an increase in body temperature or even stress due to blushing or anger.

Cholinergic urticaria can be very difficult to treat. Most treatment plans for cholinergic urticaria involve being aware of one's triggers. Drug treatment is typically in the form of antihistamines,H2-receptor antagonists such as cimetidine.

I suggest you to consult dermatologist. Take care and regards.

[Dr Rajput]

Hi, welcome to the forum, your symptoms are suggestive of cholinergic urticaria. Cholinergic urticaria is a subcategory of physical urticaria that is a skin rash brought on by a hypersensitive reaction to body heat. Symptoms follow any stimulus to sweat such as exercise (sometimes called exercise-induced urticaria), heat from the sun (which could also indicate solar urticaria), saunas, hot showers (reaction to water can also indicate water urticaria), spicy foods which may cause an increase in body temperature or even stress due to blushing or anger.

Cholinergic urticaria can be very difficult to treat. Most treatment plans for cholinergic urticaria involve being aware of one's triggers. Drug treatment is typically in the form of antihistamines,H2-receptor antagonists such as cimetidine.

I suggest you to consult dermatologist. Take care and regards.