What are the symptoms of food allergy?

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Food allergies are different from one person to another, but they mainly affect the respiratory, gastrointestinal, cardiovascular systems and skin.

Generally, allergic reactions appear immediately after the consumption of food allergens, although in some cases it may be delayed.

The allergic reaction affects one or more systems at a time and can be very severe, as shown in the table below. Anaphylaxis is the most severe reaction and appears quickly in most cases. Although there is no exact definition of anaphylaxis, anaphylactic reaction can also affect one or more of the systems identified in the following table.

Body system Reaction
Respiratory nasal congestion, dry cough, wheezing, voice change, swelling of the throat, sneezing.
Gastro-intestinal Swelling of the lips, tongue, palate; nausea, diarrhea, abdominal pain, vomiting (mostly projectile), difficulty swallowing.
Cardiovascular Acceleration or slowing of heart rate, decreased blood pressure, loss of consciousness.
Cutaneous (skin) Urticaria (red spots), swelling, itching.


In allergic infants, diarrhea or constipation are often observed, as well as projectile vomiting, blood in the stool, refusal to drink, growth retardation and gastrointestinal discomfort that can last for more than 4 hours per day.

Food allergies affect 5-6% of children and tend to appear before the age of 4 years. It is interesting to note that more and more children and adults seem to be diagnosed with food allergies.

Children are more at risk of developing food allergies when a member of the immediate family (a parent or a sibling) suffers from food allergies or an atopic disease (eczema, asthma and allergic rhinitis).

If an allergy is suspected in the child, a doctor should be consulted as soon as possible.


Agriculture, pêcheries et alimentation Québec. (2014). Les allergies alimentaires.


Béland, N., Besner, M.E., Brochu, E.E., Lecours, I., Vaillancourt, V. (2013) Prévention et traitement des allergies alimentaires : de la grossesse à l’âge scolaire. Association Québécoise des Allergies Alimentaires, p. 1-25

L’Association des allergologues et immunologues du Québec. (2011-2015). Allergies alimentaires.


L’Association des allergologues et immunologues du Québec. (2011-2015). L’anaphylaxie.


Panel NI-SE, Boyce, J.A., Assa'ad, A., Burks, A.W., Jones, S.M., Sampson, H.A., ... Matthew, J.F. (2010). Guidelines for the diagnosis and management of food allergy in the United States: report of the NIAID-sponsored expert panel. The Journal of allergy and clinical immunology, 126(6 Suppl):S1-58.


Allergies Québec (2014): http://allergies-alimentaires.org/fr (référence générale).

Naître et grandir. (2015). Les allergies alimentaires.

Santé Canada. (2013). Les allergies alimentaires et les intolérances alimentaires.


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