Why Do I Feel Itchy When I Exercise?
It’s a complaint that’s all too common but not often discussed. Just as you’re getting warmed up, the sensation hits, and you must. scratch.NOW. But why? Theories abound: Could it be the stubbly effects of a missed shaving session? A weird skin reaction to sweating? Something more nefarious?
Good news: You’re not allergic to your own perspiration, says dermatologist Yan Isabel Zhu, M.D., who also has a Ph.D. in exercise physiology and nutrition. Further, “the concentration of salt in sweat is negligible, so it should not be a factor in itching,” she says. Instead, the most likely causes are: A) a histamine release due to either friction from tight workout clothing or from body heat generated from physical activity, or B) an allergic reaction to the chemicals or materials in your exercise clothes.
“Both physical friction and heat can stimulate mast cells in our skin to release histamine, which is the same inflammatory factor that causes the symptoms of seasonal allergies, such as runny nose and itching rash,” says Zhu. A good experiment to see if this is the problem would be to try working out in loose-fitting clothes to see if you go symptom-free.
In the second scenario, there may be chemicals left from manufacturing on new, unwashed clothing, or from softener residue on the fabric after washing. You could also be reacting to some fabric materials used to make the stretchy exercise clothing, which some people are allergic to. “Allergic reaction does not develop all of a sudden,” says Zhu. “There is often an insidious onset, which means that your body gets sensitive over time by being exposed to the allergen.” Wash new clothes before wearing with mild detergent and no fabric softener. Notice if you react when wearing only one or a few pairs of pants and compare fiber contents to see if there is a common culprit. You may also find 100-percent cotton fabric more comfortable, itch-wise, than ones made with synthetics like polyester, Spandex, or Lycra.