Why would running cause my sister's legs to break out into a really itchy rash?

December 27, 2010 5:34 PM

Why would running cause my sister's legs to break out into a really itchy rash?

My sister and I want to train for a marathon together, but she says that when she runs for any length of time, a rash develops all over her legs that is extremely and painfully itchy. It's not chafing.

She's tried running with shorts and sweatpants, changing her soaps and lotions, shaving and non-shaving, and in different climates. She only gets the rash when she's running, not when she's walking or doing everyday errands.

What could be the cause for her rash? My theory is that it's something related to her sweat and possibly her diet.

Thanks for your help!

posted by jordanian2 to health & fitness (10 answers total)

I don't have any ideas about what could be causing the rash, but if it is sweat-related, could your sister try wearing Lycra pants or tights? The material should be right against her skin so it wicks away moisture. That might at least help with the process of elimination--if it's a sweat problem, it should largely disappear when the sweat does.
posted by guybrush_threepwood at 5:44 PM on December 27, 2010

(That should be "if you suspect it is sweat-related...")
posted by guybrush_threepwood at 5:46 PM on December 27, 2010

When I run, I get something like this, too. It's itchy and somewhat painful, but it doesn't seem to be on the surface of the skin, more like in it. I haven't been diagnosed, but there's a type of hives that is induced by physical exertion (and from a quick internet review, it looks to be called cholinergic urticari), and I suspect mine is something related to this. I find that mine is typically related to extreme temperature changes, like when I go running in the cold and take a hot shower; and it also shows at the beginning when I start working out again after taking time off. It tends to stop showing up after a couple of weeks or so, so I tend to push through and not worry about it too much.
posted by SpacemanStix at 5:48 PM on December 27, 2010 [4 favorites]

She should see a doctor, but possibly exercise-induced urticaria?
posted by phoenixy at 5:49 PM on December 27, 2010

According to some quick google-fu, this could be heat rash.
posted by J. Wilson at 5:54 PM on December 27, 2010

I don't know what this is, but I get it. I get it when I run, but not when I dance, use the elliptical, walk, hike, etc. I figured out, though, that it goes away after a couple of weeks. My completely unprofessional and probably wrong theory is that the skin is getting irritated by bouncing around so much, and that as it adjusts to that feeling (and the skin possibly tightens up) it gets better. HMMV.
posted by ohsnapdragon at 6:05 PM on December 27, 2010

Skin that is so dry that it has small cracks in it (not always visible to the casual glance) + sweat and heat = itching and rash.

So, could she try using a moisturiser for sensitive skin (like Cetaphil) after every shower?

Putting Grahams Bath Oil in every bath is good for healing dry, cracked skin as well.
posted by with the singing green stars as our guide at 6:17 PM on December 27, 2010 [1 favorite]

I get itchy hives with exercise and have for as long as I can remember. For me, anything that reduces a histamine reaction helps--taking an antihistamine, or rubbing hydrocortisone cream on the affected areas.
posted by not that girl at 6:29 PM on December 27, 2010

A good friend of mine gets something similar after hiking or walking for long peroids. It looks like a bad rash, but was actually the result of capillaries bursting...a form of vasculitis. One of the sensations aside from the itching, is a feeling like cold water is dripping down the leg even when it is dry. Either way you'll get a lot of good ideas here, however AskMe rarely has a real doctor responding....a visit to one instead is a better plan IMO.
posted by samsara at 8:36 PM on December 27, 2010

I have at times experienced this, each time when I was getting back into running during the winter. I never experienced it in warmer seasons or when running indoors. After several weeks I adapted and the itching went away but it certainly was annoying.
posted by dgran at 6:13 AM on December 28, 2010