One of the clinical manifestations of a food allergy is the emergence of spots, which can be more or less localised. What do they look like? Discover here what types of spots can appear following a food allergic reaction.
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What types of spots can food allergies cause?
Summary
Published November 13, 2024,
updated on November 13, 2024,
by
Pauline, Chemical Engineer
—
5 min read
What are the spots found in cases of food allergy?
Milk, eggs, peanuts, nuts, shellfish, fish, wheat, sesame, soy... There are many foods that can trigger a food allergic reaction. This can be of two types: mediated by immunoglobulin E antibodies or not mediated by these antibodies. The former is the most common and is due to the production of IgE antibodies specific to the food allergen, which attach to basophils and mast cells in tissues, triggering the release of inflammation mediators, such as histamine. The latter, cell-mediated, follows the generation of T lymphocytes that respond directly to the allergenic food protein and lead to the synthesis of inflammatory molecules. These then trigger a cascade of reactions, leading to the dilation of blood vessels, skin swelling and the appearance of spots due to the allergy.
The spots caused by a food allergy often correspond to urticaria.
Hives related to a food allergy are classified as acute, contrasting with chronic hives. In the former case, only a single outbreak is observed, lasting a few hours to a few days, while in the latter, the hives take several months or years to disappear. Hives present as red or pinkish patches, slightly raised, which are usually accompanied by intense itching. The hives' bumps correspond to small papules, either isolated or grouped together. The bumps generally leave no traces after their disappearance.
≈ 4 %
Adults in North America are affected by a food allergy.
1 in 5 people
experiences an episode of urticaria at least once in their lifetime.
If urticaria is one of the most common skin reactions following a food allergy, small erythematous eruptions similar to those observed in cases of eczema can also occur. These rashes usually appear in the folds of the skin, such as the crook of the elbows and the back of the knees, where heat and humidity can promote the allergic reaction. This type of skin reaction is particularly common in children suffering from atopic dermatitis, whose immune system is already predisposed to react excessively to antigens. Indeed, according to a study conducted by EIGENMANN and his team, children suffering from atopic disorders tend to be more affected by food allergies. It has been estimated that about 35% of children with atopic dermatitis have an IgE-mediated food allergy.
Important : In certain cases of food allergy, spots are accompanied by significant swelling of the subcutaneous tissues, known as Quincke's oedema, primarily affecting the lips, eyelids and throat. When it appears at the level of the larynx, it can be very dangerous as it presents a risk of suffocation. In the event of a food allergy, a rapid medical intervention is essential to mitigate the risks of Quincke's oedema and anaphylaxis, a potentially fatal severe allergic reaction.
Sources
EIGENMANN P. & al. Prevalence of IgE-mediated food allergy among children with atopic dermatitis. Pediatrics (1998).
WERFEL T. Skin manifestations in food allergy. European Journal of Allergy and Clinical Immunology (2004).
PUCCI S. & al. Allergy and the skin. Clinical and Experimental Immunology (2008).
WATSON W. & al. Food allergy. Allergy, Asthma & Clinical Immunology (2011).
SIMON D. & al. Update on skin allergy. European Journal of Allergy and Clinical Immunology (2014).
Assurance maladie Ameli. Urticaire : symptômes et causes (2023).
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