Exercise-Induced Anaphylaxis – How a Healthy Activity Can Go Awry
Who experiences exercise-induced anaphylaxis?
In the late 1970s, the first incidence of exercise-induced anaphylaxis was described. The patient had consumed shellfish and had a late onset reaction that was catalyzed by exercise. Since that day, over 1000 more cases of exercise-induced anaphylaxis have been reported. Research on these cases indicates that young adults are more likely than those of other age groups to suffer from exercise-induced anaphylaxis and that females are about twice as likely as males to experience this type of anaphylaxis. The cases also suggest that atopic disorders commonly associated with the immune system, such as asthma, eczema, or rhinitis, are often found in those who suffer from exercise-induced anaphylaxis and that jogging is the most common exercise type to lead to this aversive outcome.
What happens to you during exercise-induced anaphylaxis?
The specific symptoms and sequel of events can differ from patient to patient, but there are often many similarities among exercise-induced anaphylaxis cases. Symptoms usually appear sometime between 5 and 50 minutes into exercise and often involve fatigue, a feeling of warmth throughout the body, and an accelerated heartbeat. Of course, these “symptoms” are often felt during exercise anyway so can easily be mistaken as normal reactions to a workout. Next, a reaction will often appear on the skin with what are known as urticarial lesions. These lesions tend to be raised from the skin, measure about 10-15 mm in diameter, be pink or red in color, and cause the patient to itch. Angiodema, which is swelling much like hives, is also likely to occur at this point, particular on the face, hands, and feet. Finally, widespread symptoms can occur, including gastrointestinal issues like nausea and vomiting, cardiovascular and pulmonary issues that can make it hard to breathe or cause chest pain, and neurological issues, which can lead to loss of consciousness. Even after intervention, when the specific reaction has resolved, headaches can persist for 1-3 days.
What are the risk factors for developing exercise-induced anaphylaxis?
Why exercise-induced anaphylaxis occurs is not precisely known, but there are a number of factors that may contribute. Taking certain medications like aspirin can increase ones chances of exercise-induced anaphylaxis, as can exhaustion, menstruation, infections of the airway, insect bites, and exposure to allergens. Exposure to extreme temperatures has also led to exercise-induced anaphylaxis, particularly cold temperatures. As cold temperatures are also often problematic for those suffering from asthma, it is generally recommended that those at risk for these issues refrain from outdoor winter exercise.
For a subset of those patients who have endured exercise-induced anaphylaxis, the anaphylaxis depends critically on the ingestion of a certain food before exercise. Interestingly, the foods that can lead to this type of anaphylaxis are not necessarily the same foods normally associated with allergy, or for which the patients have an active allergy. Some foods that have led to exercise-induced anaphylaxis are: fruits and vegetables, including peaches, tomatoes, corn, and celery, dairy products, such as milk, eggs, and cheese, alcohol, shellfish, soy, garlic, rice, and wheat.
Another less common variable that has become associated with exercise-induced anaphylaxis is inheritance. Familial exercise-induced anaphylaxis was described when two siblings and their father all suffered these incidents.
Why do seemingly innocuous variables lead to exercise-induced anaphylaxis?
How and why exercise-induced anaphylaxis occurs is not well understood. Exercise is known to have both pro-inflammatory and anti-inflammatory effects, which complicates the picture of how it leads to anaphylaxis, which occurs as an effect of an extreme or excessive inflammatory response. However, certain cells of the immune system, called mast cells, have been implicated in the condition. It has been suggested that the lowered pH that occurs with exercise allows for specific activity among mast cells that can lead to anaphylaxis.
Basophils are another type of immune system cell that may be involved in exercise-induced anaphylaxis. Physical exertion leads to hyperosmolarity in the blood, and it is thought that basophils may be particularly sensitive to this change, which leads to histamine release, an event that can lead to or exacerbate anaphylaxis.
A more complicated immune response involving macrophages and lymphocytes is also possible in exercise-induced anaphylaxis, and one hypothesis has been put forward for how these cells could contribute specifically to food-dependent exercise-induced anaphylaxis. According to this theory, macrophages and lymphocytes of the immune system are sensitive to food allergens and during exercise, are released into systemic circulation. Thus, during exercise, these cells can react with mast cells and basophils and drive anaphylaxis.
Aspirin may lead to exercise-induced anaphylaxis for a variety of reasons. It, along with alcohol, enhances the absorption of allergens from the gastrointestinal tract. However, aspirin also appears to have the capacity to activate mast cells and thus prime immune cells to become more sensitive to allergens and perhaps other stimuli. Studies have shown that giving a subject aspirin will enhance their reaction to skin prick tests. Additionally, some incidents of food-dependent exercise-induced anaphylaxis have also required the ingestion of aspirin for anaphylaxis to occur.
What can you do to avoid exercise-induced anaphylaxis?
Luckily for those who suffer from exercise-induced anaphylaxis, people usually build a tolerance to exercise over time and do not continue to endure the highly stressful experience of anaphylaxis. However, being education about the risks and signs of exercise-induced anaphylaxis can help prevent such an incident, as can avoiding foods and other factors that could act as triggers for you.