Sports Medicine What Causes My Legs to Itch When I Run? By Sports Medicine, March 1, 2015 Prevent Runner’s Itch to Save Your Workout You’ve laced up your shoes, ready for today’s run. You start with a light jog, and as you pick up the pace and your body warms up, your legs start itching. Crazy, intense itching. Sometimes the itching is so extreme you have to stop and scratch, disrupting the flow of your run. This may cause you to ask yourself, “Why do I itch when I run?” Often called runner’s itch, this sensation affects many people, not just runners. In addition to running, severe itching can also happen when doing intense cardio exercise and can spread beyond just itchy legs. What Causes Runner’s Itch? The causes of itchy legs vary from something as simple as a skin reaction to your workout gear or an allergic response within the body. Regardless of the cause, finding relief for intensely itching legs will take a little trial and error. Aaron Mares, MD, a primary care sports medicine physician, explains some common causes and ways to prevent the itch. RELATED: 3 Common Running Injuries and How to Prevent Them Skin Sensitivities Sometimes the itching can be as simple as an allergic reaction to detergent or clothing material. You may not feel it normally, but sweating can make the reaction worse and cause severe itching. The same holds true for dry skin. Try rubbing on lotion before a workout or changing up what you wear to see if that helps. Look for workout gear made with moisture-wicking fabrics to minimize the amount of sweat that clings to your skin during your run. Out of Practice Being out of habit or staying sedentary too long also causes runner’s itch. If you’ve had a long layover between workouts sometimes the capillaries and arteries expand, causing a sensation that your brain reads as itchiness. If you can work through the discomfort, the itching should get better as you build up stamina. Some people who suffer intense itching have used numbing spray. RELATED: Staying Active at Work Exercise-Induced Urticaria You can recognize urticaria by whether the itching is accompanied by hives. This is an allergic response that can be caused by sweating, being too hot or too cold, or exercising. Although uncomfortable, intense itching is not a reason to hang up your running shoes thinking you’re allergic to exercise. Make sure you’re dressed appropriately for the weather, and if your itching is extreme, try taking a non-drowsy antihistamine before exercise. Histamine Response Some research suggests that histamine is released during exercise to protect against fatigue, rather than as an allergic response. Histamine works to expand blood vessels in your body but, unfortunately, sends the itchy message to your brain. As with urticaria, taking an antihistamine before running may help, and it’s possible that as you continue your regimen the itching will lessen. Still unsure about why you’re itching while running? For more information on common running injuries, visit UPMC Sports Medicine website or call 1-855-93-SPORT (77678) to make an appointment.