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Referral
Drug Allergy (Adults)
Key Messages
- All information regarding reactions, timing and implicated drugs must be included in the referral.
- For efficiency and to minimise returned referrals, use of the referral form is recommended.
- Referrals not on the referral form will be accepted as long as all the essential information is included in a referral letter.
- See here to find the latest information for GPs regarding Immunology and Allergy
Scope
- Diagnosis and management of drug allergy in adults (16 years and over)
Out of Scope
- See the following pathways for other allergic or atopic conditions:
Introduction
Adverse drug reactions can be immediate or delayed and can be allergic or non-allergic.
Clinical history and documentation of the reaction is paramount.
Document all new reactions promptly and thoroughly to assist in future investigation – see Assessment section below or (NICE guidance recommendation 1.2.3)
Signs and Symptoms
Immediate, rapidly evolving reactions
Anaphylaxis – a severe multi system reaction characterised by:
|
Onset usually less than 1 hour after drug exposure (previous exposure not always confirmed) |
| Urticaria or angioedema without systemic features | Onset usually less than 1 hour after drug exposure (previous exposure not always confirmed) |
| Exacerbation of asthma (for example, with non steroidal anti inflammatory drugs [NSAIDs) | Onset usually less than 1 hour after drug exposure (previous exposure not always confirmed) |
Non‑immediate reactions without systemic involvement
| Widespread red macules or papules (exanthema like) |
Onset usually 6–10 days after first drug exposure or within 3 days of second exposure |
Fixed drug eruption (localised inflamed skin) |
Onset usually 6–10 days after first drug exposure or within 3 days of second exposure |
Non‑immediate reactions with systemic involvement
| Drug reaction with eosinophilia and systemic symptoms (DRESS) or drug hypersensitivity syndrome (DHS) characterised by: • widespread red macules, papules or erythroderma • fever • lymphadenopathy • liver dysfunction • eosinophilia |
Onset usually 2–6 weeks after first drug exposure or within 3 days of second exposure |
| Toxic epidermal necrolysis or Stevens–Johnson syndrome characterised by: • painful rash and fever (often early signs) • mucosal or cutaneous erosions • vesicles, blistering or epidermal detachment • red purpuric macules or erythema multiforme |
Onset usually 7–14 days after first drug exposure or within 3 days of second exposure |
| Acute generalised exanthematous pustulosis (AGEP) characterised by: • widespread pustules • fever • neutrophilia |
Onset usually 3–5 days after first drug exposure |
A drug reaction is more likely if it occurred during or after use of the drug and:
- the drug is known to cause that type of reaction or
- the person has previously had a similar reaction to that drug or drug class
A drug reaction is less likely if:
- there is a possible non drug cause for the person's symptoms (for example, they have had similar symptoms when not taking the drug) or
- there were gastrointestinal symptoms only
When a person presents with suspected drug allergy, document their reaction in a structured approach (NICE guidance recommendation 1.2.3) including:
a. the generic and proprietary name of the drug or drugs suspected to have caused the reaction, including the strength and formulation
b. a description of the reaction
c. the indication for the drug being taken (if there is no clinical diagnosis, describe the illness)
d. the date and time of the reaction
e. the number of doses taken or number of days on the drug before onset of the reaction
f. the route of administration
g. which drugs or drug classes to avoid in future
None recommended prior to referral.
Specific IgE (RAST) testing to drugs should not be used in a non-specialist setting (NICE guidelines).
1. Anaphylaxis should be treated immediately according to Resuscitation Council guidelines and the patient referred to hospital for acute measurement of mast cell tryptase and further management.
2. The suspected causative drug should be stopped immediately and avoided pending further investigation if necessary
3. Promptly document the reaction thoroughly, with at minimum
a. The drug name
b. The signs, symptoms, and severity of the reaction
c. The date and time of onset of reaction after taking drug
d. Reason drug was given
4. Explain the allergy to the patient and documented in the medical records with appropriate details.
a. If there is a clear history, consider identification jewellery.
b. Advise patients to avoid drugs identified from history as likely causes of reactions
The information essential for clinical triage is outlined on the referral form.
All information regarding reactions, timing and implicated drugs must be included in the referral.
For efficiency and to minimise returned referrals, use of the referral form is recommended.
Referrals not on the referral form will be accepted as long as all the essential information is included in a referral letter.
Referral Criteria
Adults (16 years and over) with one of these drug related allergies:
1. Suspected anaphylaxis
2. Severe non-immediate cutaneous reaction
3. Reaction involving systemic symptoms, skin blistering or desquamation
4. NSAID reactions involving cardiorespiratory compromise or severe angioedema – see NICE Drug allergy for guidance
5. Beta lactam allergy when
a. Beta lactams are considered essential for management
b. There is likely to be frequent need for beta-lactam antibiotics in the future (e.g., recurrent bacterial infections or immune deficiency)
c. There is suspected allergy to at least one other class of antibiotics in addition to beta lactams
6. Suspected local anaesthetic allergy where a procedure involving local anaesthetic is needed
7. There is diagnostic uncertainty, or multiple drugs were involved (especially where the reaction is systemic)
Anaphylaxis or another suspected allergic reaction during or immediately after general anaesthesia – Please refer to Anaesthetics allergy clinic (plh-tr.PlymouthAnaestheticAllergyService@nhs.net)
Referral Instructions
Refer to Peninsula Immunology and Allergy Service
Refer via DRSS for NHS Devon patients
e-Referral Selection
- Specialty: Allergy
- Clinic type: Allergy
- Service: DRSS-South Devon & Torbay-Allergy- Devon ICB - 15N
Referral Form
Patient Information
onlinelibrary.wiley - for the management of drug allergy
Pathway Group
This guideline has been signed off on behalf of NHS Devon.
Publication date: March 2016
Updated: December 24
