DR12.4 | Cutaneous Adverse Drug Reaction Recognition — Summary & Reflection

KEY TAKEAWAYS

Cutaneous adverse drug reactions span a spectrum from benign maculopapular rashes to fatal severe reactions, and DR12.4 is about telling the dangerous ones apart. Fixed drug eruption is benign and unmistakable: one or a few well-defined dusky plaques that recur at the same site on re-exposure (culprits: sulfonamides, NSAIDs, tetracyclines, paracetamol). DRESS is a severe multiorgan reaction marked by long latency (2–6 weeks), fever, facial oedema, eosinophilia and internal organ involvement (especially hepatitis), caused by anticonvulsants, allopurinol and sulfonamides. The SJS/TEN spectrum is graded by epidermal detachment: SJS <10% BSA, SJS-TEN overlap 10–30%, TEN >30%, with painful skin, positive Nikolsky sign and mucosal erosions, caused by sulfonamides, anticonvulsants, allopurinol, NSAIDs and nevirapine, and severity assessed by SCORTEN. All three are delayed type IV reactions; the universal first action is to stop the culprit drug, and any reaction with mucosal, systemic or detachment features must be escalated as a potential severe reaction.

REFLECT

Recall the three patients from the opening — the recurring lip patch, the febrile woman weeks into a new epilepsy drug, and the man with peeling skin and raw mucosae. Now that you can name them, reflect on how easily the second and third could be mistaken for something trivial — a 'simple drug rash' or a viral illness — and what the cost of that delay would be. Consider how you will build the habit of asking every patient with a new rash about every drug started in the preceding weeks, and of looking deliberately for the warning features (mucosal erosions, skin pain, fever, facial swelling) that separate a nuisance from an emergency.