Synopsis
Recognise a common uncomplicated exanthematous drug eruption, identify features that indicate severe cutaneous adverse reaction, and document medicine causality without over-labelling.
- Typical lesions are symmetrical pink, red, violaceous or brown macules and small papules beginning on trunk, often with itch and no mucosal erosion.
- An uncomplicated eruption usually appears days after starting a medicine, but latency shortens after previous sensitisation and varies with the culprit.
- Create a complete timeline including prescriptions, over-the-counter products, contrast, vaccines and intermittent medicines started or stopped in the preceding weeks.
Key red flags
Skin pain, dusky or targetoid lesions, blisters, detachment, mucosal ulceration, facial oedema, fever, lymphadenopathy, pustules, eosinophilia or liver and kidney abnormalities require urgent escalation.
Facial oedema, high fever, skin pain, mucosal injury, blistering, detachment, pustules or purpura mandates urgent reassessment.
Investigation priorities
Identify plausible culprit exposures and competing infection.
Management branches
The eruption is symmetrical and itchy, mucosa is normal, skin is not painful and no organ or physiological abnormality exists.
- Review the medicine timeline, stop the most plausible non-essential culprit after arranging any necessary treatment substitute and record uncertainty.
- Use emollient, a site-appropriate topical corticosteroid and a non-sedating antihistamine when itch is prominent, avoiding unnecessary systemic steroids.
Key medicines
Betamethasone valerate 0.1% creamApply a thin film to affected trunk or limb skin once or twice daily for up to four weeks, using the shortest course and amount that controls inflammation.
Cetirizine 10 mg tabletsAdults and adolescents aged 12 years and over take 10 mg orally once daily, with renal dose reduction according to the current SmPC.