Severe Allergic Reactions

Overview

Severe Allergic reactions or Anaphylaxis is a potentially life-threatening, systemic allergic reaction caused by the release of histamine and other vasoactive mediators from mast cells. The risk of death is increased in patients with pre existing asthma, particularly if this is poorly controlled and in individuals in whom treatment with adrenaline is delayed.

Signs and Symptoms

Conjunctival injection, Flushing, Sweating, Stridor, Cardiac arrhythmias, Abdominal pain, Diarrhoea, Wheeze, Hypotension, Urticaria

Common Causes

IgE mediated mast cell degranulation Triggers: peanuts, nuts, fish, shellfish, antibiotics, aspirin, intravenous (IV) contrast, stings from bees, yellow jackets, wasps, hornets and fire ants

Risk Factors

Previous anaphylaxis, Allergies or asthma

Investigation Techniques

Skin prick test, Serum mast cell tryptase concentrations

Treatment and Prevention

Prevent further contact with allergen, Ensure airway patency, Administer intramuscular adrenaline promptly, Administer antihistamines: chlorphenamine, Administer corticosteroids, Provide supportive treatment such as nebulized beta agonist, IV fluids to restore or maintain blood pressure and oxygen.