Allergies associated with exercise involve the typical mechanism of any allergic reaction. An allergic reaction is the immune system’s attempt to defend the body from a perceived threat that, in reality, is harmless. During this process, chemicals such as histamines are released into the body, triggering allergy symptoms. Symptoms of this reaction may include itchy eyes, runny nose and sneezing. In some cases, the reaction is more extreme, resulting in hives, eczema (skin inflammation) or breathing difficulties.

Allergies that flare up during exercise often stem from exposure to the allergens associated with allergic rhinitis (hay fever). These include pollens, molds, dusts and animal dander. The severity of these allergy symptoms can range from merely being a nuisance to severely impacting performance (especially in athletes competing at high levels). In rare cases, allergies triggered by exercise can cause potentially life-threatening reactions.

Even minor symptoms can impact an individual’s motivation to continue to exercise. Breathing through the nostrils is an important aspect of exercising comfortably and safely, because the nose and sinuses warm the air and filter out irritants. A person who is congested will breathe more through the mouth, which can introduce irritants and allergens to the bronchial tubes and lungs.

Despite such risks, most experts strongly encourage those with allergies to continue or begin healthy exercise routines. Moderate exercise is believed to increase immune system efficiency, thus potentially decreasing the likelihood of allergic reactions. Over-training, however, is believed to have the opposite effect and actually decreases immune system efficiency. Therefore, a healthy and balanced exercise routine is important to the overall health of people with allergies.