Anaphylaxis is an acute severe systemic reaction which is most often allergic (but can be non-allergic, previously called anaphylactoid). It is commonly associated with urticaria and angioedema and occurs within minutes (typically less than 1 hour) of a trigger (eg food/drug/sting). Anaphylaxis is characterised by one or more of:
Airway – tongue/throat swelling, difficulty talking/hoarse voice
Breathing – shortness of breath, wheeze, persistent cough
Circulation – persistent dizziness or collapse, loss of consciousness
Neurological – sense of impending doom, visual changes
NICE guidance is that patients with a history of anaphylaxis should be referred to a specialist allergy clinic, and according to the specialist services national definition set 17 for allergy, “patients with anaphylaxis must be seen in a specialist allergy centre and not managed in the community”.
For guidelines describing the management of urticaria and angioedema in the absence of systemic features see guidance for spontaneous urticaria and angioedema.
When to consider referral:
Consider referral of patients with anaphylaxis, particularly for patients with:
Drug reactions in whom:
- There is diagnostic uncertainty or multiple drugs were involved (especially where the reaction is systemic or involves blistering or desquamation)
- The suspected drug is considered essential for the patient’s ongoing management, and where alternatives clinically not suitable. Please document reasons for needing treatment with the drug.
- Venom allergy
- No obvious trigger
- Cofactors (eg asthma, cardiovascular disease).
Patients with an obvious food trigger and no cofactors need not be referred
Primary care management prior to referral
Anaphylaxis should be treated immediately according to Resuscitation Council guidelines.Acute measurement of mast cell tryptase (immediately and 2 hours after the onset of symptoms) should be performed.
Identify any potential triggers (eg foods, drugs, stings, exercise) in the 4 hours before the reaction.
Drugs – Ensure potential drug allergies are explained to the patient, and documented in the medical records with appropriate details.
If there is a clear history consider identification jewellery.
Advise patients to avoid potential triggers identified in the history pending further investigations. If a suspected trigger has been tolerated since the reaction it is excluded as a cause.
Prescribe self-injectable adrenaline (0.3mg x 2) with appropriate training to patients with:
- Anaphylaxis (see definition above) or a less severe allergic reaction in patients with asthma;
- A potentially unavoidable suspected cause.
All patients must have appropriate training in use of self-injectable adrenaline. Guidance is available at https://www.epipen.com/en/about-epipen/how-to-use-epipen
Drug reactions are not an indication for self-injectable adrenaline, as drugs can usually be avoided unless there is altered consciousness.
Information required with referral
Details of index reaction with copy of appropriate correspondence (eg ED discharge summary) and suspected triggers.
List of regular medications
Stings – check specific IgE to bee and wasp venom and mast cell tryptase.
Foods – check specific IgE to specific suspected foods 4 weeks after index reaction. There is no need to investigate foods which were not directly implicated or have been tolerated since the reaction.
Drugs – no investigations needed.
Clinic options available
We have no Choose and Book slots available – we review and triage all referrals ourselves and allocate clinics appropriately.
Review Date 13/8/2019
Next Review Date 13/8/2020
Author Dr Andrew Whyte, Consultant Allergist and Immunologist, Derriford Hospital
GP Sifter Dr Isabel Boyd
Version No. 1.2