Your body reacts to exercise in a number of different ways while you are in the midst of a workout. Your heart rate elevates, you sweat, your muscles may feel stretched or tired and your skin may itch. Skin itching during exercise can range from just being annoying to bordering on life-threatening in some cases. Speak to your doctor if your skin consistently itches during exercise or if you notice any other skin changes during your workout.
Skin itching during exercise that is accompanied by hives is called exercise-induced urticaria. The lesions can range in size and usually appear after you have been working out for several minutes. Food allergies are thought to be the cause of this form of exercise-induced itching, even if you ate the offending item hours before physical activity.
Heat rash, called miliaria, is another condition in which you may experience itching during your jog or other workout. A heat rash occurs when your body temperature rises and you begin to sweat.
Exercise-induced hives most commonly break out on your upper torso and neck, but the itching and associated lesions can appear anywhere on your body. You may also experience a headache or flushing when you notice the hives. Hives that appear on your face and in your throat, called angioedema, can be life-threatening, and require immediate medical attention. Once you stop exercising, the hives usually recede within 20 minutes; the itchiness may linger.
A heat rash will most often appear well into your workout when you have worked up a good sweat, though on a humid day, you can experience a rash very quickly. You will see small red bumps on the surface of your skin, these are blockages of the sweat ducts that cause the rash and subsequent itching.
Treatment for itchy hives that appear during exercise is to stop what you are doing and take an antihistamine. People who experience frequent exercise-induced urticaria may carry injectable epinephrine to ease symptoms. Treatment for an itchy heat rash is to avoid sweating and to cool off your skin through cold compresses and antihistamines to relieve itching.
Exercise-induced hives tend to be a long-term problem for most people. After experiencing several episodes of the hives and studying the other factors that come into play, such as the type of exercise in which you were engaged and what you might have eaten before you exercised, you and your doctor may be able to determine what exactly is causing the itchy breakouts. Sometimes, changing your eating patterns or exercise routine can help curb the itching, but for other people, exercise-induced urticaria and the associated discomfort is a chronic condition that can be managed but not necessarily cured.
Similarly, if you are predisposed to developing heat rashes while exercising, you may suffer from this problem throughout your workouts if the weather conditions are right. Your medical care team can help you tweak your physical activities to decrease your chances of itching during exercise.