Urgent considerations

See Differentials for more details

Anaphylaxis

Recognise anaphylaxis by the sudden onset and rapid progression of symptoms: life-threatening airway and/or breathing and/or circulation problems with or without skin and/or mucosal changes after exposure to a trigger (allergen).[14][15][42]

Intramuscular adrenaline (epinephrine) should be given promptly to patients who have symptoms of anaphylaxis after accidental ingestions of allergic foods.[15][43]​​[44]​​​​ Delay in administration of adrenaline is associated with fatal outcomes. Generalised urticaria, angio-oedema, and rhinitis without life-threatening airway, breathing, or circulation problems do not meet the criteria for anaphylaxis, however if in doubt, give intramuscular adrenaline and seek expert help.[15]

Additional attention should be given to basic life support measures, as indicated, including supporting the patient’s airway, breathing, and circulation. Guidelines on anaphylaxis should be referred to for detail on acute and subsequent management.[15][43][44][45][46][47]​​​​​​​​​

Adrenaline auto-injectors are available should anaphylaxis occur outside of a medical setting. Those at high risk for anaphylaxis, and their carers, should be counselled on the carrying and use of adrenaline auto-injectors, as well as the recognition and avoidance of exposures.[47]​ The American Academy of Allergy, Asthma & Immunology recommends that more than one auto-injector is prescribed if patients have previously required multiple doses of adrenaline to treat an anaphylactic reaction and/or have a history of biphasic reactions.[47]​ Children should receive a personalised, written emergency plan.[46][48][49] American Academy of Pediatrics: allergy and anaphylaxis emergency plan Opens in new window​​​ 

A delay in administration of adrenaline is associated with biphasic reactions, in which patients develop recurrence of symptoms some time after initial resolution.[50]​ Additional risk factors for biphasic anaphylaxis include severe anaphylaxis and/or the need for >1 dose of adrenaline, wide pulse pressure, unknown anaphylaxis trigger, cutaneous signs and symptoms, and drug trigger in children.[43][47]​ Adults and young people aged 16 years or older who have had emergency treatment for suspected anaphylaxis should be observed for 6 to 12 hours from the onset of symptoms, depending on their response to emergency treatment.​[45] If the symptoms were controlled promptly and easily, a shorter observation period may be considered, provided appropriate post-reaction care is given prior to discharge.​[45]

There is increased risk of fatal anaphylaxis due to food allergy in patients with asthma, patients allergic to peanuts or tree nuts, and adolescents.[51][52] In adolescents this is thought to be due, in part, to risk-taking behaviours such as intentionally eating the allergic food and/or not carrying their injectable adrenaline auto-injectors.

Food protein-induced enterocolitis

Infants who suffer from food protein-induced enterocolitis typically present 2 hours after milk or soya ingestion with profuse vomiting, diarrhoea, irritability, and lethargy, which may progress to dehydration and shock.[16][29] Such infants may need rapid intravenous rehydration to treat voluminous fluid losses from the gastrointestinal tract.

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