What is this rash? (with pictures!)

I’ve been riding my bicycle a lot, and whenever the temperature gets over about 90 degrees my legs start breaking out in a rash. The worst is on the tops of my thighs, but I will also get it on my calves and ankles. It’s red, puffy, and very sensitive. It extends about 3 inches above and below where my bike shorts hit on my leg.

Ignore the gnarly tan line :stuck_out_tongue:
Pic 1
Pic 2

I’ve tried using different sun screen and different bike shorts, but the only thing that seems to make a difference is the temperature outside.

Any ideas on what I can do to prevent it or treat it?

Looks like urticaria, aka hives. Some common causes are heat, moisture, irritation, excercise, etc. It’s an allergic reaction, but not always caused by allergens. I used to get them years ago on clothing contact points when exercising. The thing I found most helpful was putting a lotion containing dimethicone on those areas before working out, but it still didnt totally prevent it.

Dang, Speak, looks like that’s what it is. Next time, could you diagnose me with something easier to treat? :stuck_out_tongue:

You might try switching laundry products. I get hives around the underwear waistband from fabric softener dryer sheets.

Turble, I considered that but I don’t use dyer sheets or fabric softener on my workout clothes. They air dry and I already use a hypoallergenic laundry soap.

Try shorts without the elastic cuffs, or roll the elastic up over the lyrca a bit to see if it makes a difference?

I vote for the laundry products. I switched to dash or all or even a baby diaper laundry soap. I think it has more to do with caustics than allergens.

I used get something a little like that sometimes - contributing factors seem to be sun exposure (not always heat) and sunscreen - it’s only ever where the sun hits my skin - gets really hot and itchy, and it’s not sunburn.

From what I’ve read some sunscreens contain chemicals that can cause photosensitivity and a rash when exposed to the sun. I changed my sunscreen to a more physical block and it’s been a few years since I last had it. Can’t be sure it’s the same thing, but could be worth considering.

I’m allergic to all sunscreen and get hives just like that if I use it.

I don’t think it’s caused by the laundry soap since it’s just on my legs, but I went ahead and bought some “all” brand to try on my workout clothes. We’ll see if it makes any difference this weekend!