MYTH: “An allergic reaction always occurs immediately after ingesting an allergen.”

FACT: An allergic reaction can occur immediately after ingesting an allergen, but it can also be delayed.

immediate allergic reaction

Most allergic reactions to foods are usually triggered within the first 30 minutes or up to 2 hours after ingestion. These immediate-type or hypersensitivity reactions mediated by IgE antibodies result from the excessive production of antibodies specific to a particular food. In general, they can affect the skin and/or mucous membranes, the respiratory tract and the gastrointestinal and cardiovascular systems, either alone or in combination.

delayed allergic reaction

Other manifestations of food allergy include delayed reactions, beginning more than two hours after eating the food, after the food has been digested. Late reactions are usually not mediated by IgE and result from a hypersensitivity mechanism mediated by other cells of the immune system, particularly lymphocytes and eosinophils. These manifestations most often occur on the skin and digestive tract. (1)

Surveillance of allergy symptoms after ingestion of suspected food

The time it takes for an allergic reaction to food to manifest is in some cases impossible to predict, varying with the type and amount of allergen ingested, the mechanisms involved in the reaction (IgE antibodies, cells or both), the degree of individual sensitivity of the person. For this reason, whenever the ingestion of a food that is suspected to contain or be contaminated with the allergen in question occurs, it is vital to monitor the occurrence of symptoms for at least the following 24 hours and to be prepared to act immediately in accordance with the emergency schedule given by the doctor. (two)

All Fidu products are free from the 14 main allergens and their traces, because we want to provide tasty and safe alternatives for everyone, regardless of their dietary restrictions.

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IMPORTANT NOTE: The content of this article is for informational purposes only. If you suspect that you have an allergy, seek medical advice.

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(1) SPAIC Food Allergy Interest Group, 2019. Food Allergy: Concepts and Advice and Precautions, 2nd Edition. Lisbon: Portuguese Society of Allergology and Clinical Immunology with support from Thermo Fisher Scientific and BIAL Laboratories.

(2) Nunes, M., Barros, R., Moreira, P., Moreira, A., Almeida, M. (2012). Food allergy. Ministry of Education and Science - Directorate-General for Education & Ministry of Health - Directorate-General for Health.