• anaphylaxis;
  • exercise;
  • food allergy;
  • Liliaceae;
  • onion allergy

Hypersensitivity to onion has been described as a cause of contact dermatitis, rhinoconjunctivitis and asthma induced by handling of onions (1). However few publications in the literature report allergic reactions due to onion ingestion (2–4).

We describe the case of a 26-year-old woman who reported at least 10 episodes of generalized cutaneous erythema with itching, urticaria, angioedema of the face, profuse sweating, malaise, chest tightness, wheezing, and dyspnea during the last year. These episodes began when running for 30 minutes in different environments, and usually improved with rest, but the reactions became increasingly severe and the last ones required treatment in the emergency room with epinephrine (adrenaline), antihistamines and corticosteroids. The patient was a soldier and had to train daily. She had not related these episodes with any drugs, foods, latex, insect stings or menstruation.

We advised the patient to make a detailed list of events and a diet diary in case new reactions occurred. She reported two new episodes: the first while she was training, three hours after eating chicken cooked with tomato, onion, red pepper, and Avecrem (a commercial chicken sauce). The second happened after she had been dancing; one hour previously she had eaten a salad with potato, raw onion, tuna, oil and vinegar.

The patient had a clinical history of rhinoconjunctivitis and asthma due to sensitivity to grass pollens. The physical examination showed no anomalies.

Laboratory investigation revealed normal complete blood count, differential, erythrocyte sedimentation rate, urinalysis, liver and renal function tests, thyroid hormones, electrolytes, coagulation studies, quantitative serum immunoglobulins, immune complexes, C3, C4, CH50, C1-esterase inhibitor, urinary levels of catecholamines and 5-hydroxyindoleacetic acid, and serologic tests for Echinococcus. Electrocardiogram and chest X-rays were normal.

Skin prick tests to common inhalants proved positive to mites and Phragmites, and mugwort pollens. Skin prick tests with commercial food extracts (ALK-Abello) were positive to banana, onion and nuts (almond, peanut and walnut). Total serum IgE was 1090 UI/ml. IgE antibody levels specific to onion were 100 kU/l, to garlic were 3.5 kU/l, to lettuce 2.40 kU/l, and to tomato 0.85 kU/l (CAP System, Pharmacia).

Prick-by-prick tests with raw and cooked onion, banana, garlic, lettuce, leek and asparagus were positive. The same tests were negative with raw and cooked chicken, tuna, tomato, red pepper, potato, and Avecrem.

Food challenges using the same foods, but performed at rest, were negative.

Exercise challenge was carried out using a treadmill with appropriate personnel and equipment for treatment of anaphylaxis. The patient gave written informed consent before the study. First, the test was performed in a fasting state and resulted negative. The next day we repeated the test two hours after eating chicken cooked with all the ingredients except onion, and it was negative again (we suspected the allergen responsible was onion because it was involved in both documented reactions). Finally, on the third day, the challenge was made two hours after eating 30 g of cooked onion. After 10 minutes of running the patient presented generalized urticaria, dyspnea, and nausea, and we observed a fall of 30% in the forced expiratory volume in one second (FEV1). She was treated with epinephrine (adrenaline), corticosteroids, and antihistamines, and improved within 20 min.

The patient was instructed to carry injectable epinephrine (adrenaline) while exercising, not to exercise alone and not to consume onion within 6–8 h of exercising. She has had no new episodes during the last two years.

IgE-mediated food allergy to onion seems extremely rare despite its wide use. We have found three reports in the literature (2–4), only one of which is a case of food-dependent exercise-induced anaphylaxis (2). All patients reported were sensitized to raw onion but tolerated cooked onion; in our case, the patient was highly sensitized (IgE antibody level of 100 kU/l) to both raw and cooked onion.

Like other authors, we have not found cross-reactivity with other members of the Liliaceae family (garlic, asparagus or leek) (5).


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  2. References
  • 1
    Valdivieso R, Subiza J, Varela-Losada S et al. Bronchial asthma, rhinoconjunctivitis, and contact dermatitis caused by onion. J Allergy Clin Immunol 1994;94:928930.
  • 2
    Hicks CD, Tanner SB. A case of food-dependent exercise-induced anaphylaxis to onion. Ann Allergy Asthma Immunol 1998;80:86(abstract).
  • 3
    Arena A, Cislaghi C, Falagiani P. Anaphylactic reaction to the ingestion of raw onion. A case report. Allergol Immunopathol 2000;28:287289.
  • 4
    Asero R, Mistrello G, Roncarolo D, Mato S. A case of onion allergy. J Allergy Clin Immunol 2001;108:309310.
  • 5
    Sanchez-Hernandez MC, Hernández M, Delgado J et al. Allergenic cross-reactivity in the Liliaceae family. Allergy 2001;55:297299.DOI: 10.1034/j.1398-9995.2000.00460.x

Accepted for publication 8 April 2002