It has Been Displayed That Exercise Can Provoke Anaphylaxis
Strenuous exercise occasionally produces a type of exercise-induced anaphylaxis, sometimes in combination with certain foods.
Recognized since the 1970s, the problem is most often triggered by arduous exertion in joggers, runners, cyclists, soccer players, skiers and those engaging in vigorous aerobics. Its symptoms mimic anaphylaxis triggered by allergens — skin itching, diffuse flushing, often large (dime-sized) hives, swelling of the throat, hands and face, nausea and vomiting and lightheadedness.
After an exercise-provoked episode, many people have a severe, persistent headache for 72 hours or longer.
In contrast to classic anaphylaxis, the exercise-induced form is not IgE-related but is due to direct stimulation of mast cells, which makes them release the mediators responsible for symptoms.
Sometimes the itching, hives, swelling and other effects are triggered not only by exercise-generated heat and sweating but by any kind of heat — for instance, taking a sauna or hot shower. Known as cholinergic urticaria, these forms usually cause smaller hives and less dramatic symptoms, and are sometimes exacerbated by stress.
Since there is not always much warning of an anaphylactic reaction, epinephrine should be self-injected at the first hint of a reaction, or on exposure to a known or suspected allergen.
For someone who has collapsed in allergic shock on a previous occasion, the physician may suggest that an injection be administered immediately after a sting by a suspect insect, or contact with a dangerous drug or food, even before any reaction appears.
“Whatever the reason for anaphylaxis,” as one expert puts it, “it’s better to act fast than to wait and be sure there will be a reaction. If you wait, it may be too late.”
Food-dependent exercise attacks are another variant; they occur only if strenuous exercise is done within two to four hours of eating a meal, or after consuming specific foods (such as celery, wheat or shellfish), or when taking a particular medication such as ASA. The food or drug sets the scene and exercise finishes the job.
Some experts believe exercise-provoked anaphylaxis is becoming more common with the rising popularity of jogging, aerobics and other fitness programs. The people most susceptible are the allergy-prone. Attacks are more common or worse when exercise is done in humid conditions, in very cold air, during the pollen season or, in women, during a menstrual period.
Diagnosing the condition may mean taking a “challenge test” — exercising on a treadmill or applying heat to see if symptoms appear. Blood tests sometimes show clearly elevated histamine levels during and after attacks.
Treatment of exercise-induced anaphylaxis is the same as for other anaphylactic reactions — injection of epinephrine, oxygen administration if needed, corticosteroids, antihistamine-mines to blunt the severity and careful medical monitoring. Antihistamines have been used before exercise in attempts to forestall an allergic attack, but their use is not promoted as they cannot be relied on to stop the anaphylaxis.
The guidelines include the following measures:
• Inject epinephrine if available from an emergency kit. Rub the site vigorously afterwards to increase absorption.
• Those known to be severely allergic may be carrying an emergency kit such as the Ana-Kit or EpiPen, containing a preloaded syringe. In case of an allergic reaction, people can self-inject or be helped to do so.
• Call emergency medical services immediately.
• Place a conscious person lying down and elevate the feet by about twelve inches (30 cm), if possible.
• Place an unconscious person on his/her side to aid breathing.
• Monitor the person and evaluate the need for CPR, if you are trained in that procedure.
Far more important are avoidance tactics — not exercising in humid conditions, avoiding vigorous activity for four hours after eating, heeding early warning signs and stopping exercise at the slightest hint of an oncoming attack — as soon as there’s any skin itching, hives, flushing, swelling or dizziness.
Sometimes, the reaction can be muted by starting an exercise program very slowly and working up to full speed.