Experiencing itchy, red legs after running can cause discomfort and might force you to curtail a workout. Weather conditions, allergic reactions and even the clothes you wear during the run can all cause itchiness and redness of the legs. Fortunately, most leg itchiness and redness is treatable with home care or medication and preventable with changes in exercise routines.
In some runners, leg itchiness and redness after a run results from the body's immune system overreacting to the increase in basal body temperature during exercise. An allergic reaction to a poisonous plant such as poison ivy, an insect bite or sting; the detergent used to launder the running clothes; or the fabric of the running pants might cause your legs to itch and appear red after running. An allergic reaction to a food that you ate before running might also cause redness and itching of the skin. Running in extreme heat might cause the legs to feel itchy and look red, as can running in bright sunlight with bare legs.
If your leg itchiness and redness is accompanied by any symptoms of anaphylaxis, including difficulty breathing, swelling of the lips or throat, faintness, dizziness, mental confusion, a racing heartbeat or vomiting, these are signs of a serious allergic reaction that requires urgent medical care. While waiting for evaluation, the Mayo Clinic website suggests loosening any garments around the chest and legs, lying down with the legs elevated above the head and administering the contents of an epinephrine pen or taking an antihistamine pill.
For leg itchiness and redness after running that results from an insect bite or sting, go indoors away from any more insects and remove the stinger if it is still in your leg, advises the Mayo Clinic website. Hold a cold compress over the area to reduce itchiness and swelling and apply a hydrocortisone gel, calamine lotion or paste made with three parts baking soda to one part water to the leg as often as needed for relief. If these home care strategies do not relieve your itching and redness, dermatologists often recommend taking an antihistamine to treat the symptoms. Severe cases of leg itching after running might require treatment with an injection of epinephrine by a physician.
Keeping a log of when itchiness occurs and the circumstances such as location where running took place, what clothing you wore, what the weather was like and what you ate before running might help detect a pattern to the itchiness and help your efforts to prevent these symptoms. Taking an antihistamine before running might help prevent itchiness and redness in the legs. Before running outdoors during the warmer months, consider applying an insect repellent to the skin before running, to help deter insects from biting the legs and causing itchiness. For runners with a sensitivity to certain fabrics, wearing cotton jogging pants or opting for cotton shorts instead of pants can help reduce skin irritations from fabric.