Some people experience itchiness, redness and even hives from sweating, which sounds like a great excuse to stop exercising, but it doesn’t always translate into an allergy. (Nor, unfortunately, does it give you carte blanche to stop working out.)
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To begin with, there are different stages of this kind of reaction. Some, for example, merely feel a brief period of itchiness when they’re hot and sweaty (say, after a workout), while others can go into anaphylactic shock if they overheat — although this is a rare occurrence.
On the less severe end of the spectrum, isolated itching from sweat can be due to a number of factors, including the type of clothing you’re wearing and what you’ve applied to your skin before putting yourself in a situation that will induce sweating.
“Things that cause allergies are foreign things that your body attacks,” Arielle Nagler, an assistant professor of dermatology at NYU Langone Health, said to The Cut. “So instead of sweat, it could be that sweat changes something about someone’s deodorant or a fragrance, and that could be triggering the allergy.”
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In other words, a lotion or fragrance that you’re applying before going to the gym may have an irritant in it that’s triggered by sweat, which could cause an itchy reaction.
Nagler also points to the contradictory nature of moisture-wicking materials that most people wear to the gym. While they work to keep the sweat off your body, they also don’t breathe easily, so you’re still trapping heat on your skin.
“Warm environments promote yeast. And wicking products especially tend to be really occlusive and itchy, so changing immediately and trying to shower can be really helpful,” she said.
If you tend to have a more pronounced reaction in the form of hives, the underlying cause could be cholinergic urticaria (CU), which is caused by nerve fibres in the sweat glands. A chemical in the nervous system acts as a transmitter that initiates a response (in the form of a rash) when it’s released in the skin’s nerve endings.
While most people who experience this might mostly attribute it to getting sweaty from exertion, it can also be triggered by taking a hot shower or bath, eating spicy foods, stress, anxiety, or abruptly moving from a hot room to a cold one. The good news is, the rash usually doesn’t last more than 80 minutes.
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In its most severe iteration, CU can put a person at risk of anaphylactic shock. Julie Reid, a former dance instructor in Clearwater, Fla., went public with her sudden and debilitating case of CU in 2016 with the hope of raising awareness of the rare condition.
“Any physical activity I do, I develop hives everywhere,” she said to WFTS.
The television report noted that they could not interview Reid on the porch of her own home because any overheating can cause a breakout.
On her blog, she says that her condition “led to a crippling development of agoraphobia, and a toxic combination of apathy and depression.”
At the moment, the best course of treatment for CU includes avoiding activities or foods that could cause a reaction, taking antihistamines, and in some cases, a doctor may recommend a short duration of steroids. Some specialists believe a low antihistamine diet, which excludes, salty foods, fish and shellfish, preservatives and additives, nuts, dairy, alcohol, and many fruits and vegetables, can help with chronic reactions.