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A severe systemic allergic reaction involving both circulatory and respiratory changes, often accompanied by skin changes. It can be fatal if not diagnosed, addressed and treated quickly and correctly. The Resuscitation Council defines anaphylaxis by the following ABC criteria: 

  • Life-threatening Airway and/or Breathing and/or Circulation problems 
  • Skin and/or mucosal changes (flushing, urticaria, angioedema) in up to 80% of cases
  • Sudden onset and rapid progression of symptoms
  • Diagnosis is further supported if the patient has been exposed to a known allergen 


Early IM injection with adrenaline is the treatment of choice. Give adrenaline IM at midpoint of anterolateral thigh (through light clothing if necessary). Repeat after 5 mins if condition not improved or getting worse. ALWAYS FOLLOW LATEST GUIDANCE. Adrenaline dosage for anaphylaxis is:

  • Adult or child >12 years: 0.5 ml of 1:1000 solution (500 micrograms)
  • Child 6–12 years: 0.3 ml of 1:1000 solution (300 micrograms)
  • Child under 6 years: 0.15ml of 1:1000 solution (150 micrograms)

Individuals at risk of anaphylaxis need to carry an adrenaline autoinjector at all times, and need to be instructed in advance when and how to inject it. Latest guidance is that:

  • Two injection devices should be carried at all times to treat symptoms until medical assistance is available; if, after the first injection, the individual does not start to feel better, the second injection should be given 5 to 15 minutes after the first.
  • An ambulance should be called after every administration, even if symptoms improve
  • The individual should lie down with legs raised (unless they have breathing difficulties, when they should sit up) and, if possible, should not be left alone.

Autoinjection devices should be prescribed by brand name as instructions for use vary between devices, and it is essential that the individual has the type of injector that they have been instructed how to use.

The Anaphylaxis Campaign website has guidance for health professionals on how to use these devices.

Practice Nurse featured article

Dealing with emergencies in general practice: Anaphylaxis Beverley Bostock-Cox 

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