Anaphylaxis

Anaphylaxis is a serious and potentially fatal allergic reaction that can progress rapidly. It typically causes more than one of the following: an itchy rash, throat closing due to swelling that can obstruct or stop breathing; severe tongue swelling that can also interfere with or stop breathing; shortness of breath, vomiting, lightheadedness, loss of consciousness, low blood pressure, and medical shock.

These symptoms typically start in minutes to hours and then increase very rapidly to life-threatening levels. Urgent medical treatment is required to prevent serious harm and death, even if the patient has used an epinephrine autoinjector or has taken other medications in response, and even if symptoms appear to be improving.

Common causes include allergies to insect bites and stings, allergies to foods—including nuts, peanuts, milk, fish, eggs; allergies to medications – including some antibiotics and non-steroidal anti-inflammatory drugs (NSAIDs); or allergies to anaesthetics or latex. Other causes can include physical exercise, and cases may also occur in some people due to escalating reactions to simple throat irritation or may also occur without an obvious reason. The mast cell disease mastocytosis, along with the mast cell disorder mast cell activation syndrome are both capable of triggering anaphylaxis.

The mechanism involves the release of inflammatory mediators in a rapidly escalating cascade from certain types of white blood cells triggered by either immunologic or non-immunologic mechanisms. Diagnosis is based on the presenting symptoms and signs after exposure to a potential allergen or irritant.

The primary treatment of anaphylaxis is epinephrine injection into a muscle, intravenous fluids, then placing the person in a reclining position with feet elevated to help restore normal blood flow.