Anaphylaxis
Overview
- The BNF provides guidance on anaphylaxis in the ‘Medical emergencies in the community’ section
Symptoms
- Anaphylaxis has a sudden onset, with symptoms rapidly worsening. The main symptoms are:
- Feeling light-headed or faint (from a drop in blood pressure)
- Difficulty in breathing or wheeze (from bronchoconstriction)
- Increased heart rate (due to a lower cardiac output with lower blood pressure)
- Clammy skin, confusion or anxiety and finally a loss of consciousness (all related to low blood pressure)
Treatment
- If available, administer an adrenaline (epinephrine) auto-injector (e.g. EpiPen® or Jext®) intramuscularly into the upper outer thigh as soon as possible. If there is no improvement after 5 minutes, a second dose should be given if another device is available
- A needle-free adrenaline nasal spray (EURneffy®) is also licensed for emergency self-treatment of anaphylaxis: the 2 mg spray for adults and children weighing 30 kg or more (the UK 2 mg licence is weight-based; the EU combined labelling specifies 4 years and over), and the 1 mg spray (approved by the MHRA on 12 June 2026) for children aged 4 years and over weighing 15–30 kg. One spray is given into a nostril and works even if the nose is congested. As with auto-injectors, two doses should always be carried, and a second dose should be given into the same nostril after 5 minutes if there is no improvement before the ambulance arrives
- Where a healthcare professional draws up adrenaline from an ampoule (adrenaline 1:1000), the Resuscitation Council UK intramuscular doses are: adult and child over 12 years 500 micrograms (0.5 mL); child 6–12 years 300 micrograms (0.3 mL); child 6 months to 6 years 150 micrograms (0.15 mL); child under 6 months 100–150 micrograms. Repeat after 5 minutes if there is no improvement
- Some manufacturers provide online training on how to administer their adrenaline product
- Call 999 immediately and inform the controller that the patient is having an anaphylactic reaction
- Remove any trigger where possible e.g. stings
- Adrenaline is the only treatment for anaphylaxis. Antihistamines, oral steroids and reliever inhalers are not a substitute and must never be allowed to delay it. Auto-injector device strengths are 150 micrograms (child 7.5–25 kg), 300 micrograms (25 kg and over) and 500 micrograms (adults); a second dose is ideally given in the opposite thigh
- Help the patient to lie flat with their legs raised to support their circulation. If they are having difficulty breathing, allow them to sit up instead. Do not allow the patient to stand or walk, as this can cause a rapid deterioration