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Definition of anaphylaxis

  • Anaphylaxis is a severe, life-threatening generalised or systemic hypersensitivity reaction which is likely when both of the following criteria are met:
    • sudden onset and rapid progression of symptoms
    • life-threatening airway and/or breathing and/or circulation problems
  • Skin and/or mucosal changes (flushing, urticaria, angioedema) often also occur but are absent in a significant proportion of cases
  • Gastro-intestinal symptoms (vomiting, diarrhoea, abdominal pain) can also be associated with symptoms of anaphylaxis
  • Skin/mucosal and gastrointestinal symptoms without airway, breathing or
    circulation symptoms are systemic allergic reactions, but not life threatening
    reactions and therefore not classified as anaphylaxis

Recognition of anaphylaxis

  • Anaphylaxis is likely when the following two criteria are met:
    • sudden onset and rapid progression of symptoms
    • life-threatening airway and/or breathing and/or circulation problems
  • The following supports the diagnosis:
    • additional skin and/or mucosal changes (flushing, urticaria, angioedema)
    • gastrointestinal symptoms (vomiting, diarrhoea, abdominal pain)
    • exposure of a person with allergy to their known allergen
  • Please note:
    • skin/mucosal and gastrointestinal symptoms on their own are not signs of anaphylaxis
    • skin and mucosal changes can be subtle or absent in up to 20% of anaphylaxis (some patients can have only a decrease in blood pressure, i.e., a circulation problem, or isolated airway or breathing symptoms)

Triggers of anaphylaxis

  • The following are the most commonly identified triggers for anaphylaxis in childhood:
    • food (56%)
      • peanut, tree nut, milk, egg, fish, and shellfish
    • drugs (5%)
      • antibiotics–penicillins and β-lactams
      • muscle relaxants during anaesthesia
    • insects (5%)
      • wasp/bee
  • Other causes include latex which is particularly associated with spina bifida or multiple operations
  • A significant proportion of cases are idiopathic
  • Exercise-induced anaphylaxis is a syndrome of anaphylaxis only occurring after exercise. It mainly affects teenagers and is often associated with food (food dependant, exercise-induced anaphylaxis)

Clinical presentation

  • Sudden onset and rapid progression of symptoms
  • Anaphylaxis usually occurs within 2 hours of allergen exposure

Presenting symptoms

  • Airway problems:
    • hoarse voice
    • stridor
  • Breathing problems:
    • shortness of breath
    • wheeze
    • confusion due to hypoxia
    • cyanosis
    • respiratory arrest
  • Acute severe bronchospasm occurs in most cases of death due to food-induced anaphylaxis
  • Life-threatening asthma with no other features of anaphylaxis can be triggered by food allergy
  • Anaphylaxis can present as a primary respiratory arrest
  • Circulation problems:
    • signs of shock–pale, clammy
    • increased pulse rate (tachycardia)
    • low blood pressure (hypotension)
    • decreased level of or loss of consciousness
    • myocardial ischemia and ECG changes
    • cardiac arrest
  • Cutaneous symptoms
    • pruritis
    • erythema
    • urticaria
    • angioedema
  • Gastrointestinal symptoms:
    • vomiting
    • diarrhoea
    • abdominal pain

Emergency management of anaphylaxis

  • Follow the Royal College of Paediatrics and Child Health care pathway:
    • recognise the signs and symptoms of anaphylaxis
    • initial assessment and treatments based on ABCDE approach
    • early administration of intramuscular adrenaline
    • call for an ambulance
    • transfer to emergency department
  • Emergency treatment should be provided according to Resuscitation Council UK Guidelines Anaphylaxis Algorithm (2008)
    anaphylaxis management algorithm

Resuscitation Council UK Guidelines Anaphylaxis Algorithm (2008) reprinted with kind permission of theResuscitation Council UK.

Patient Positioning

Please note:

  • Lie patient on their back and raise legs if tolerated
  • Individuals with respiratory distress or vomiting may not tolerate lying flat, place in a position of comfort with the lower extremities raised
  • Do not ask patient to stand up or sit up during anaphylaxis, due to the risk of sudden death from empty ventricle syndrome

Remove anaphylaxis trigger/allergen exposure

  • Remove patient from allergen trigger/allergen exposure if possible:
    • stop any drug suspected of causing an anaphylactic reaction (e.g., stop intravenous infusion of a gelatin solution or antibiotic)
    • remove the stinger after a bee sting. Early removal is more important than the method of removal
    • remove patient from source of inhaled allergen (e.g. horse, cat. dog)
  • After food-induced anaphylaxis, attempts to make the patient vomit are not recommended
  • Do not delay adrenaline treatment if removing the trigger is not feasible

Adrenaline (epinephrine)

  • Adrenaline is the most important drug for the treatment of an anaphylactic reaction; other medications should be regarded as second line treatments. Rapid treatment is important as adrenaline works best if given early after the onset of the reaction


  • Adrenaline should be given to all children with life-threatening features—an anaphylactic reaction involving any respiratory and/or cardiovascular symptoms or signs

Route of administration

  • Adrenaline should be injected via the intramuscular route as soon as anaphylaxis is diagnosed or suspected
  • The intramuscular route is recommended when given by patients, families and most healthcare providers. Adrenaline should only be given intravenous (IV) by healthcare professionals experienced in the use and titration of vassopressors in their normal clinical practice (e.g. anaesthetists, emergency physicians, intensive care doctors)


  • There are no absolute contraindications for the use of adrenaline in children. Adverse effects are extremely rare with correct doses injected intramuscularly but adrenaline can cause life-threatening hypertension or arrhythmias when given IV

Second-line treatments/medication in anaphylaxis

  • IV fluids—rapid IV fluid challenges are indicated if cardiovascular symptoms (e.g. signs of shock, low blood pressure), persist after intramuscular adrenaline treatment
  • Oxygen—High flow oxygen given through a mask with oxygen reservoir should be given if cardiovascular and or respiratory symptoms persist after intramuscular adrenaline treatment
  • Antihistamines—used alone antihistamines are not life saving in anaphylaxis. Given in addition to adrenaline, antihistamines may help counter histamine–mediated vasodilation and bronchoconstriction and may treat associated skin and gastrointestinal symptoms
  • Corticosteroids—given in addition to adrenaline as second line medication for anaphylaxis, corticosteroids may help prevent or shorten prolonged reactions and/or biphasic reactions, in particular late asthmatic responses
  • Salbutamol—additional treatment with salbutamol may relieve symptoms of wheezing, coughing shortness of breath not relieved by adrenaline

Further hospital management

  • Monitor in hospital for minimum of 6–12 hours, due to the risk of prolonged and/or biphasic reactions
  • Children and young people younger than 16 years who have had emergency treatment for suspected anaphylaxis should be admitted to hospital under the care of a paediatric medical team
  • Ensure a full allergy focussed clinical history and examination has been completed
  • Where the trigger allergen is unclear consider specific IgE testing at this admission. Do not do skin prick tests for 3-4 weeks after anaphylaxis due to the risk of systemic allergic reactions
  • Mast cell tryptase testing is only indicated for drug, venom or idiopathic anaphylactic reactions in children and young people under 16
  • Dietary advice on avoidance for food allergens
  • Basic avoidance advice for non-food allergens
  • Optimise management of other atopic disease with onward referral if needed
  • Written and verbal emergency care plan for any future reactions
  • Prescription of two adrenaline auto injectors
  • Training on adrenaline auto injector
  • Arrange follow up and provide contact number for family of a healthcare professional competent in the management of anaphylaxis, education and support of family

Discharge from hospital

  • Prior to discharge children must be provided with a basic prevention and treatment package including:
    • adrenaline auto injector
    • training in the use of the auto-injector
    • information about anaphylaxis, including signs and symptoms and what to do in an emergency
    • basic avoidance advice
    • a referral to an allergy clinic or a paediatrician with an interest in allergy

Adrenaline for self administration

  • Children who have suffered an anaphylactic reaction should be provided with an adrenaline auto-injector prior to discharge
  • Adrenaline injectors should be prescribed by brand name rather than generically and training should be given in the use of the individual device prescribed
  • It is recommended that children should be prescribed 2 auto-injectors, this is due to the possibility of the device misfiring or failure to respond to the first dose
  • There is no self-injectable adrenaline device licensed for children under 15 kg but the balance of risk favours providing infants and children over 7.5 kg with a 150 microgram adrenaline auto-injector

Follow-up/outpatient care comprehensive management package—RCPCH Guidelines

  • Review diagnosis and update allergen avoidance advice
  • Review need for further testing or planned challenges
  • Update emergency treatment plan
  • Review need for additional training
  • Continue age appropriate education of child

full guideline available from…

Children and Young People's Allergy Network Scotland. Recommendations for anaphylaxis management for children and young people in Scotland. September 2013.  
First included: June 2015.