anafylaktisen

Anaphylaxis, from the Greek words anaphallē (sudden) and aksiōn (action), is a severe, systemic allergic reaction that can occur rapidly after exposure to a trigger. It is characterized by the sudden onset of symptoms such as itching, hives, swelling, wheezing, and in severe cases, difficulty breathing, low blood pressure, and loss of consciousness. The reaction results from the release of mediators such as histamine and leukotrienes from mast cells and basophils, which cause widespread inflammation and vascular leakage.

Triggers commonly include foods (peanuts, shellfish, tree nuts, eggs, milk), insect stings (wasps, bees), medications (penicillin, aspirin, nonsteroidal anti-inflammatory drugs), and latex. People with a history of severe allergic reactions or asthma are at greatest risk. However, anaphylaxis can occur in anyone without prior symptoms.

The diagnosis is clinical, based on rapid onset of symptoms affecting at least two organ systems and known exposure to a probable allergen. There is no definitive laboratory test; blood tryptase levels may support the diagnosis but often normalise quickly.

Immediate treatment is the intramuscular injection of epinephrine, which reverses airway constriction, vasodilation, and edema. Subsequent care includes oxygen, antihistamines, and corticosteroids, and monitoring in an emergency department. Severe cases may require intubation and vasopressor support.

Prevention involves identifying and avoiding triggers, carrying epinephrine autoinjectors for at-risk individuals, and wearing medical alert identification. In patients with known severe allergies, especially those with a history of anaphylactic reactions, allergist-guided immunotherapy may be considered.