Why You Get Runner’s Itch and How to Stop It

You’re on a run and in a nice groove. Then all of a sudden, an odd type of pain slowly creeps up your legs, like tiny ants are marching up and down. One of the most common, overwhelming sensations a runner can experience is itchy legs, also known as runner’s itch. It’s an annoying situation that can halt your run. And no matter how much you scratch, the itchy sensation doesn’t seem to go away.

If you’ve ever wondered: why do my legs itch when I run, and how can I solve this discomfort? Read on for the answer and possible solutions.

When it comes to runner’s itch, there are several causes. We’ll take you through what might be happening and how to treat it. (Good news first: There’s no sudden cause for alarm. In most cases, itchy legs are a mere annoyance, not a severe issue or symptom of a larger problem.)

What Causes Runner’s Itch?

There are several reasons you might experience mid-run itchiness, but it seems to be more common in new runners or those coming back to running after a long break. If that sounds like you, you may also experience uncomfortable welts or rashes, says running coach Lora Erickson.

Here are a few other reasons you might be experiencing this annoying condition.

Increased Blood Flow

As your heart rate increases, so does your blood flow, which causes the capillaries and arteries in your muscles to expand. The capillaries stay open to allow for maximum blood passage when you’re fit, but if you’re out of shape, your capillaries tend to collapse, not allowing as much blood to pass through. When your capillaries expand, the surrounding nerves become stimulated and send messages to the brain, which reads the sensation as itching.

Histamine Release

This is sort of interesting: According to a 2017 research review, exercise may promote the release of histamine to prevent fatigue instead of as an allergic reaction. Histamine causes your blood vessels to expand, which contributes to the itchy sensation.

Sensitive Skin

You may be especially prone to runner’s itch if you have sensitive skin. Allergies to certain laundry detergents, fabric softeners, or clothing materials can cause itchiness. The combination of sweating and dry skin can worsen the irritation.

Exercise-Induced Urticaria

Exercise-induced urticaria is an allergic response that occurs when you experience itchiness along with hives or redness of the skin. (Additional symptoms can include stomach cramps, headache, difficulty breathing, and swelling of the face, tongue, or hands.)

It typically occurs during or after strenuous exercise, such as running or hiking, especially when you do these activities in hot or cold weather.

Exercise-Induced Vasculitis or Purpura

Exercise-induced vasculitis is also known as golfer’s vasculitis or hiker’s rash. This inflammatory condition involves red patches, purple spots, and swelling on the thighs and lower legs. The itchy rash is accompanied by intense stinging, pain, and burning. (Genetics may make you more prone to exercise-induced vasculitis. Usually, symptoms resolve on their own within a matter of days.)

Exercise-induced purpura, on the other hand, occurs in people who run marathons, take long walks, or engage in unusual physical activity. It’s especially common during hot weather in the mountains. It causes blood spots to occur on the lower legs.

According to medical experts, other possible causes of runner’s itch include: food allergies, alcoholic drinks, medications, including aspirin, and other allergic reactions.

Why Do Legs Tend to Itch More in Cold Weather?

When we run in cold weather, blood vessels in the skin shut down to limit blood flow to the skin and prevent cooling of the blood and associated heat loss.

When we stop running and step into that hot shower, the skin is immediately warmed, and blood vessels in the skin dilate again. The sudden vasodilation is associated with a triggering of the itch fibers also located in the skin, and this is why there is such a sudden and often intense itch in the legs, especially where blood, warmed by the working muscles, has an enhancing effect on both the amount of vessel dilation and the effect on itch fibers.

After a brief period, once the skin is warmed, the blood vessels return to their normal state, and the itch fibers will no longer be activated, making the “runner’s itch” lessen. It should be self-evident from this explanation that this phenomenon is not only completely normal but also not dangerous in any way and does not require a visit to a healthcare provider.

Why Itching Makes You Itch More

One last observation from the world of itch science, it is not at all uncommon that when you have an itch, scratching it can make it itchier as opposed to less.

Diana Bautista, a professor at the University of California, Berkeley, with expertise in physiology and neuroscience, explains: “Itching and scratching activate the reward center of the brain. Dopamine neurons in the brain’s reward center not only promote scratching but also drive reinforcement—the release of dopamine is pleasurable and drives more scratching by activating the itch-scratch neural circuits.” Furthermore, “scratching can trigger an addictive and vicious itch‐scratch cycle, whereby scratching breaks the skin to worsen itch and promote the release of more itchy mediators like histamine and neuropeptides.” She told me.

Basically, it’s like trying to quell a fire with gasoline—it might seem satisfying at first, but it often backfires.

How to Prevent Runner’s Itch

Remember, more often than not, this condition is temporary and not a cause for concern. Plus, Erickson says there are plenty of steps you can take to prevent itchy legs:

• Keep exercising to allow the body to adapt. (This is probably the biggest one.)
• Stay hydrated.
• Use moisturizing lotions after showering.
• Take a warm bath with oatmeal, Epsom salts, or baking soda.
• Apply aloe vera gel, hydrocortisone cream, or a cold compress to the itchy area.
• Consider changing your laundry detergent to something milder.
• Shave your legs! Yes, even in the winter.
• Wear compression sleeves and elevate your legs for 15 minutes at a time, a few times per day, to help improve circulation.

To prevent runner’s itch, keep up with your regular exercise routine. After a few workout sessions, your legs will get used to moving, and the itch should subside. If you experience rashes or welts after a week of consistent movement, you should speak with your doctor.

It’s important to remember that, just as your face turns red during exercise, itchy legs while running aren’t cause for alarm unless the itch is accompanied by hives. If you’re also experiencing stomach cramps, swelling of the face or tongue, or difficulty breathing along with the itchiness, seek medical attention immediately.

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