This site is intended for healthcare professionals

Go to /sign-in page

You can view 5 more pages before signing in

Different types (and timing) of drug allergic (allergy) reactions

Last reviewed dd mmm yyyy. Last edited dd mmm yyyy

Authoring team

Signs and allergic patterns of suspected drug allergy with timing of onset

Immediate, rapidly evolving reactions

  • Anaphylaxis - a severe multi-system reaction characterised by:
    • erythema, urticaria or angioedema and
    • hypotension and/or bronchospasm
  • Urticaria or angioedema without systemic features
  • 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)
  • 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

Common disorders caused, rarely, by drug allergy:

  • eczema
  • hepatitis
  • nephritis
  • photosensitivity vasculitis

Time of onset variable

With respect to DRESS, study evidence (2) found:

  • most common drug causes were found to be antibiotics (74%) and anticonvulsants (21%)
  • most common comorbidities were epilepsy (26%) and hypertension (26%)

Reference:


Create an account to add page annotations

Add information to this page that would be handy to have on hand during a consultation, such as a web address or phone number. This information will always be displayed when you visit this page

The content herein is provided for informational purposes and does not replace the need to apply professional clinical judgement when diagnosing or treating any medical condition. A licensed medical practitioner should be consulted for diagnosis and treatment of any and all medical conditions.

Connect

Copyright 2024 Oxbridge Solutions Limited, a subsidiary of OmniaMed Communications Limited. All rights reserved. Any distribution or duplication of the information contained herein is strictly prohibited. Oxbridge Solutions receives funding from advertising but maintains editorial independence.