itchy blisters

My 9 year old son has been getting itchy round blisters a few hours after soccer practice.  For the hour before his practice he plays on a playground with recycled tire mulch.  They started showing up the third week of practice.  The first time it happened, he just had a few - the second time was last night and he had a lot.  They covered his arms and trunk.  These blisters show up 2-3 hours after practice ends and he is still in the process of settling down for the night.  The blisters drive him crazy with their itching.  By 4-6 hours after they appear, they are gone with no trace that they were ever there.  Any idea what could be causing them?

[Toby89]

I am by no means a medical professional, but I do have a similar reaction to being in grass or around furry animals. Mine is just an allergy, and they either settle down on their own or with the help of an antihistamine. That might help your son! But like I said, I'm not a medical professional. Good luck!

[Bhupinder Kaur, MD]

Hello,
It looks like hives which come and go in response to an allergy. You can give him some antihistaminic like benadryl or Claritin. Although the bite may be itchy, avoid scratching it because you may damage the skin, and allow bacteria to get in, leading to infection. You may also need topical and oral steroids which are available under prescription. Also try to find the offending allergen (grass, dust, plants etc) which may be causing this allergic reaction.
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.