History
Exercise-induced anaphylaxis (EIA) is characterized by signs and symptoms of anaphylaxis in the setting of physical activity. If physical exertion continues, symptoms progress in severity. Premonitory symptoms of exercise-induced anaphylaxis attacks include diffuse warmth, pruritus, erythema, and sweating. These are followed by typical urticarial lesions and angioedema that can progress to include GI symptoms, laryngeal edema, and/or vascular collapse.
Symptoms may begin at any stage of exercise. Cessation of the physical activity usually results in immediate improvement or resolution of symptoms. However, some patients may experience vascular collapse even after exercise cessation.
The frequency of symptoms during exercise varies among patients with exercise-induced anaphylaxis and food-dependent exercise-induced anaphylaxis. Most patients exercise regularly but experience attacks only occasionally. In patients with food-dependent exercise-induced anaphylaxis, episodes typically occur when the person exercises 1-3 hours after eating. The duration of exercise prior to the development of symptoms may range from less than 30 minutes to a maximum of 45 minutes.
The most common signs and symptoms, along with their relative frequency of occurrence, are as follows: [1]
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Pruritus (92%)
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Urticaria (86%)
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Angioedema (72%)
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Flushing (70%)
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Shortness of breath (51%)
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Dysphagia (34%)
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Chest tightness (33%)
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Syncope (32%)
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Profuse sweating (32%)
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Headache (28%)
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GI symptoms, including nausea, diarrhea, and colicky pain (28%)
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Choking, throat constriction, hoarseness (25%)
Clinicians should also carefully review the events leading up to the episode of anaphylaxis with a special focus on the following:
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Was each of the attacks associated with exercise? If not, then other causes of anaphylaxis should be investigated
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Do symptoms subside when the patient stops physical activity?
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Do activities that raise body temperature in the absence of exercise (eg, hot baths, saunas, or showers) induce symptoms? Symptoms triggered by changes in core body temperature are suggestive of cholinergic urticaria
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Are any medications, changes in environment, or other exposures associated with the episodes?
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What foods has the patient eaten before each episode?
Patients with exercise-induced anaphylaxis commonly experience attacks for over 10 years, with an average of 14 attacks per year, before their disorder is diagnosed. The frequency of attacks is diminished in patients who have avoided known triggers or reduced their physical activity.
Physical Examination
Physical examination findings may be highly variable in patients with exercise-induced anaphylaxis or food-dependent exercise-induced anaphylaxis. Signs of chronic allergic disease such as eczema, “allergic shiners,” and boggy nasal mucosa suggestive of allergic rhinitis may be noted.
A careful skin examination should be performed to evaluate for dermatographism and urticaria pigmentosa, which are characteristic findings in mastocytosis. Urticaria pigmentosa is characterized by oval or round red-brown macules, papules, or plaques. Mastocytosis may present with anaphylaxis that is precipitated by exercise and in response to various different triggers; therefore, excluding this disorder is important.
Cardiac examination should be performed to exclude abnormal heart sounds because exercise-induced cardiac disorders are also in the differential.
Respiratory symptoms
During an episode, severe angioedema of the tongue and lips may obstruct airflow. Laryngeal edema may manifest as throat constriction and stridor. Hoarseness, change in voice, dysphagia, or a sensation of choking may occur. Bronchospasm, airway edema, and increased mucus production may manifest as wheezing and chest tightness.
Cardiovascular symptoms
Tachycardia usually occurs as a compensatory response to reduced intravascular volume and endogenous catecholamine release during an episode. Hypotension can occur secondary to capillary leak, vasodilatation, and myocardial depression. Cardiovascular collapse and shock can occur in the absence of other findings and patients may present with syncope.
Cutaneous symptoms
Hives can occur anywhere on the body. The lesions are generally large (giant hives) and are erythematous, raised, and highly pruritic. Angioedema is also commonly observed. These lesions involve the deeper dermal layers of skin. It is usually nonpruritic and nonpitting. Generalized flushing and profuse sweating may also be observed.
Gastrointestinal symptoms
Vomiting, diarrhea, and colicky abdominal pain are frequently observed.
