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What is runner's itch? Experts discuss how to prevent the annoying sensation

Experts explain what causes it and how to avoid it.

There’s nothing quite like having the crescendo of your run interrupted by itchy legs.

That itchiness is exercise-induced urticaria, commonly known as runner’s itch, and experts say it varies in frequency and intensity depending on the person. Some runners may have to stop in the middle of a run to scratch their legs because the itchiness is so intense while others may not experience it at all.

“Some people get this and they get it all the time,” sports medicine physician Dr. Jordan Metzl told TODAY Health in a Zoom interview. “Some people get this — they get it for a while and it goes away. I wish I could tell you it was related to the more you run, the less likely you are to get it. But it's not really true. We don't totally understand why some people get this and some don't.”

Experts said that runner's itch is more likely to occur during cooler months, like in the fall and winter.Mitch Diamond / Getty Images

What causes runner's itch?

Dr. Sarina Elmariah, a dermatologist at Massachusetts General Hospital and a professor at Harvard Medical School, said the itchy feeling is a result of circulatory systems working properly. Chemicals are released when the nerves in the skin, blood vessels and sweat glands work together to thermoregulate the body while increasing oxygen and blood flow to the muscles. That process can lead to itchiness.

“That's probably the most common and just fundamental process that happens,” she said. "Some of those chemicals can bind to what we believe are itch receptors ... that can really modulate or induce a type of itching sensation. Some people don't experience itch. They experience like prickling or burning instead of itch, but these sensory phenomena travel together.”

Exercise-induced urticaria most commonly happens while running, but it can happen during any type of exercise. And since it’s primarily caused by proper blood and oxygen circulation, Metzl and Elmariah said there isn’t much that can prevent it. The good news is they said it’s not a cause for concern and more so just an annoyance.

“It’s generally not a big deal,” Metzl said. “And like many problems in medicine, if you give a little bit of time, it'll go away by itself.”

How to prevent runner's itch:

Celebrity fitness trainer Jeanette Jenkins, who founded the Hollywood Trainer Club, said a key way to increase circulation and avoid itchiness is to properly hydrate and warm up before workouts. Jenkins recommends hydrating with liquids that have electrolytes and fully warming up to prepare the body for physical activity.

Kickstarting blood flow before working out means the body won't have to do as much circulatory work while exercising, Jenkins said.

“We all know what it feels like to be sitting down, and then start moving," Jenkins said. "When we're sitting and we're not doing anything, the majority of our blood is sitting in the core of our body. And so we need to get it out to the extremities, to the muscles, through your legs and your arms.”

In addition to the circulatory process that prompts itchiness, there are idiosyncratic factors causing the itchiness. Elmariah said some people are predisposed to itchiness in response to physical activity or sweat. She said fluctuations in ambient or body temperatures can sometimes trigger cells to destabilize, causing itchiness and even hives for some people.

Remedies include varying the length of clothing worn to protect exposed skin, changing laundry detergents and trying over-the-counter topicals with lidocaine to soothe the skin, Elmariah said. She suggested seeing a doctor if the itchiness becomes prohibitive.

Metzl said runner’s itch should not be a deterrent to exercising: “Although it's annoying, it’s not something that's going to keep most people on the sideline.”