Going for a run is a good way to get your heart rate up and get a workout in. But sometimes just as you start to work up a sweat, your legs start itching like crazy. So much so that you can’t continue running without stopping to scratch. Soon enough you’ll be asking, “Why do I itch when I run?” This condition is known as runner’s itch, but doesn’t affect runners exclusively - it can happen during any kind of intense cardio activity. And it may not just be your legs that end up itching.
Why Do I Feel Itching When I Run?
Also known as hives, urticaria typically happens to about 20 percent of the population at some point in their lives. It is usually triggered by a substance, food, or activity. Urticaria starts as a small patch of itchy skin that eventually develops into swollen, red welts. The hives can be mild to severe. When urticaria is triggered by running or other intense exercise, it is not life-threatening, but continuing to exercise may make the hives worse.
If your hives are accompanied by additional symptoms such as difficulty breathing, nausea, and lightheadedness, you may be experiencing exercise-induced anaphylaxis. Usually, this happens with vigorous exercise, but could potentially happen with any kind of physical activity. Exercise-induced anaphylaxis is life threatening and extremely rare, but if you’ve had an episode, you should carry an epinephrine injector that will reverse the symptoms.
If you’re only asking yourself "Why do I itch when I run?" only when it’s cold outside, you may have cold urticaria. The symptoms are similar to that of regular hives, and can appear anywhere on skin that’s exposed to the cold. Sometimes people can get more severe symptoms, including chills, fast heartbeat, and swelling of the extremities.
One of the more simple causes of itchy skin while running is you’re just not used to exercising. The small blood vessels known as capillaries in your legs collapse if you haven’t exercised in a while. Therefore when you start running or exercising, the increased blood flow causes the capillaries to expand. This can cause the surrounding nerves to send itching signals to your brain. Typically, once your body adapts to exercise, the itching stops.
Another simple explanation is that your skin is having an allergic reaction to a new laundry detergent or the material of your clothing. Sweating can intensify the reaction and make it worse.
There are some studies that have found that histamine is released during exercise to prevent your body from getting tired. Histamines are chemicals made by the immune system to help your body get rid of an outside invader. Itching is a side effect of this process since when histamines open up your blood vessels, they also cause itching.
Can I Prevent It When Running?
Change your laundry detergent
If using a new type of laundry detergent seems to be the cause of the itching, using a different one can be an easy solution. There are also hypoallergenic detergents which contain no dyes and perfumes that can potentially irritate sensitive skin.
Making sure your skin isn’t dry can be helpful in preventing itchy skin while exercising. Dry skin can be itchy even without being irritated by exercise. Look for a moisturizer that does not contain a lot of perfumes or dyes.
Run or exercise indoors
If your skin is sensitive to the cold or other environmental allergens, it may just be easier to work out indoors where you can control the temperature and your exposure to any other allergens.
Try taking an antihistamine beforehand
If allergens or the environment aren’t causing your itching, and you’re still asking "why do I itch when I run?", it might be worth taking an antihistamine before you run. It will help your body’s reaction to any histamines which are releasing as a response to exercise.
Don’t run long distances
If you have exercise-induced anaphylaxis, it’s usually triggered by intense exercise. It’s a good idea to avoid any potential triggers as anaphylaxis can be life threatening. Light jogging or short-distance running may be a compromise you have to make.
Keep track of your itchy episodes
Keeping a journal of what you did and ate before you went running could help you figure out a pattern that’s contributing to your symptoms. This could help pinpoint the trigger for your itching.
You lose a lot of water during exercise, and it’s easy to become dehydrated. Dehydration can make your body release more histamines and contribute to itchiness. Be sure to drink a lot of water before, during, and after your run.
Shower less often
Showering very long periods of time and often can actually dry out your skin and cause itchiness. Showering only once per day is recommended, and using cooler water can also help keep moisture in your skin.
Wear different clothing
The material of some workout clothes can cause skin irritation, particularly when mixed with sweat. Try different fabrics or wash your workout clothes in hot water and see if that eliminates the itching.
Talk to your doctor
If itching during running persists for more than a month, making you ask "why do I itch when I run", it’s probably a good idea to see your doctor to get some potential solutions. They can run more extensive allergy tests and potentially see what your skin is sensitive to.