It's possible that you could have a folliculitis. How long does the rash last? Folliculitis is common on the buttocks.
To prevent, disinfect your wetsuits after each use. You could use a chlorhexidine wash for this. I'm not sure listening would work. If you have an older wetsuit, you might try a weak bleach solution. not sure id want to use bleach on a jice,new wetsuit.
Make sure the wetsuit is then given a chance to dry completely.
---------- Post added June 7th, 2013 at 04:04 PM ----------
Check out the Thermocline wetsuit from Fourth Element. It's a neutrally buoyant 2m. I have an allergy to the formaldehyde used in the wetsuit glue/seals and the Thermocline is hypo-allergenic. I just got it and used it in Maui - temps averaged 76 degrees. The second day I wore it under my 3m wetsuit. The Fourth Element stuff is amazingly well made and did I mention the Thermocline is machine washable? I highly recommend it to everyone. Hope that helps.
I wear a cheap, Lycra skin under any of my wetsuits. This could help to prevent rashes caused by allergy. Just make sure its a plain, Lycra skin. I love mine. It's great as a sunscreen and also helps a wet,wetsuit glide on easily, even if you're sticky with sweat. I won't dive a wetsuit without it!
---------- Post added June 7th, 2013 at 04:07 PM ----------
Dor, I have that reaction too with wetsuits. I've had to get steroid shots and steroid packs after breaking out so bad with rashes and hives. Yesterday I bought a drysuit to eliminate the problem after so much frustration with trying to find a wetsuit I could(n't) wear.
Zig, have you tried the Lavacore suit? I found that i am allergic to wetsuits. I was unable to find Thermocline suit but was recommended the lavacore suit which looks and feels identical. But I still had a reaction to the lavacore when I wore it under a new 3 mil suit. Also, how did you find out that it was the formaldehyde that you were allergic to? The allergist I went to basically just said there weren't any real tests for it and said to stay away from wetsuits. :-/
You can always do a patch test. Tape a piece of neoprene to your skin and wear it for a day or so. I bet your dive shop would have a scrap piece they could give you. It only needs to be about the size of a dime.
---------- Post added June 7th, 2013 at 04:11 PM ----------
If it turns out you are allergic, do not keep exposing yourself to the allergen. Comtact allergies can become quite serious. I actually had a patient with a latex allergy who went into anaphylactic shock when a glove was used while a foley catheter was being placed. We didn't know she had this allergy, she told us about it after things settled down and she was back with us. She did, however, have more allergies than anybody I've ever seen, so who knows!
Does this happen with short, shallow dives or only on "beefier" dives? Have you checked to make sure the rash doesn't look like skin bends?