Hives Cause #1: Exercise-Induced Anaphylaxis
Symptoms: In addition to hives, other symptoms of exercise-induced anaphylaxis (EIA) include: breathing difficulties (shortness of breath, wheezing), circulatory problems (lightheadedness, low blood pressure) and gastrointestinal symptoms (nausea, vomiting and diarrhea).
Cause: Many people who suffer from EIA have another trigger that, along with exercise, causes the symptoms. These triggers include various medications; foods such as seafood, nuts, or dairy; alcohol; and cold weather. Typically, symptoms are not triggered by just exercise or the specific trigger alone.
Prevention/Treatment: You should stop exercising immediately. You may need to use an epinephrine injection pen to stop the symptoms, as you would do for an anaphylaxis reaction caused by a food or insect sting allergy.
People with EIA should avoid: cold weather exercise, exercise on an empty stomach, and eating any food triggers for at least 24 hours before exercise. You should always run with someone who knows about your condition. Talk to your medical care professional for advice and tests so you know what triggers to avoid.
Hives Cause #2: Cholinergic Urticaria
Symptoms: Itching, swelling, and small hives on the skin.
Cause: This type of reaction is caused by the increase in body temperature that occurs while running, most often during hot weather.
Prevention/Treatment: Medicines, such as antihistamines, can be taken to help prevent symptoms. You should also avoid running on hot or humid days and reduce your workout intensity. Stop exercising at the first sign of itchy skin or hives.