Anaphylaxis

Definition

A severe and potentially life-threatening systemic allergic reaction characterized by rapid falling blood pressure and airway obstruction.

How it works

Anaphylaxis is the most severe form of allergic reaction, involving a rapid and widespread response of the immune system. It involves massive degranulation of mast cells and basophils, releasing large amounts of histamine and other mediators. Symptoms typically appear within seconds to minutes after exposure to the allergen, affecting multiple biological systems simultaneously: skin (hives, flushing), cardiovascular (hypotension, tachycardia), respiratory (bronchospasm, asphyxiation), and gastrointestinal (nausea, diarrhea). Without immediate treatment with epinephrine injections, anaphylaxis can be fatal.

Role

No biological benefit; a dysfunctional immune response requiring emergency medical intervention.

Examples

• Severe penicillin allergy
• Severe peanut allergy
• Seafood allergy
• Vaccine reaction
• Latex allergy

Recommendations

Individuals at risk of anaphylaxis must always carry an auto-injector of epinephrine (EpiPen). Call emergency services (15 in France, 112) immediately if symptoms appear. Wear an allergy alert card or bracelet listing critical allergens.

Key takeaway

Anaphylaxis is a medical emergency requiring immediate access to epinephrine and emergency services.

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