What should you know about IgE in anaphylaxis?

Immunoglobulin E, usually called IgE, is an antibody involved in allergic reactions. After sensitisation, IgE may recognise a trigger such as a food, medicine, insect venom or another allergen. Contact can activate cells that release inflammatory chemicals. The result may include hives, swelling, wheezing, vomiting, dizziness or trouble breathing. An IgE result can support an allergy assessment, but it does not by itself show that anaphylaxis will happen or identify how severe a future reaction will be.

Treat suspected anaphylaxis as an emergency. Use prescribed adrenaline immediately if available, call emergency services, and explain that a severe allergic reaction is happening. Lie down with legs raised unless breathing is difficult; then sit with legs extended. Do not stand or walk suddenly. A second adrenaline dose may be needed if symptoms continue and your emergency plan allows it. Further assessment is needed even if symptoms improve. Learn more about [Anaphylaxis Emergency Treatment](/treatments/acute-and-urgent-care/anaphylaxis-emergency-treatment/) and [Anaphylaxis](/conditions/anaphylaxis/).

Call emergency services immediately for throat or tongue swelling, difficulty breathing, wheezing, faintness, confusion, widespread hives with vomiting, or rapidly worsening symptoms. A reaction can progress quickly, so do not wait for an IgE test or a routine appointment. [Wheezing](/symptoms/wheezing/) can be one sign of airway involvement, while [Food Allergy](/conditions/food-allergy/) is one possible trigger.

Ask which trigger is suspected, whether specific IgE testing or another form of [Allergy Testing](/treatments/diagnostics-and-screening/allergy-testing/) is appropriate, how to use your adrenaline device, and what your written emergency plan should say. Discuss medicines or foods to avoid and whether close contacts should learn the response steps.