Drug Eruptions AND Severe Cutaneous Adverse Reactions

The answer first

Drug eruptions span from trivial morbilliform rashes to life-threatening Stevens-Johnson syndrome/toxic epidermal necrolysis (SJS/TEN), DRESS, and drug-induced anaphylaxis. The first decision is to recognise the severe cutaneous adverse reaction (SCAR) and act immediately. ^[1]

A physician-level answer rests on four pillars: ^[1]

1. Recognise the SCAR phenotype and act immediately. Skin pain (SJS/TEN), facial oedema with eosinophilia and transaminitis (DRESS), rapid generalised pustulosis (AGEP), or hypotension with stridor (anaphylaxis) — stop culprit, escalate, transfer to burns/ICU for SJS/TEN with detachment > 10 percent BSA. ^[1]
2. Stop the culprit drug. Single most important intervention in any drug eruption. Common culprits: penicillins, cephalosporins, sulfonamides, anticonvulsants (carbamazepine, phenytoin, lamotrigine), allopurinol, nevirapine, NSAIDs (particularly oxicam class). ^[12]
3. Apply mechanism-specific therapies. Supportive care is the cornerstone for SJS/TEN (Society of Dermatology Hospitalists 2020 guidelines). DRESS responds to systemic corticosteroid. AGEP is largely self-resolving with drug withdrawal. Anaphylaxis needs IM adrenaline. ^{[3] [4]}
4. Pharmacogenomic stratification by ancestry. HLA-B15:02 is strongly associated with carbamazepine-induced SJS/TEN in Han Chinese, Thai, and south-Asian populations — screen before prescribing. HLA-B58:01 with allopurinol SJS/TEN in Han Chinese, Thai, Korean. HLA-B*57:01 with abacavir hypersensitivity in all patients. ^[7]

DWE high-yield: "Skin pain + blistering + mucosal involvement + target lesions + recent drug" = SJS or TEN. Use the % BSA detachment rule: < 10 percent = SJS, 10 to 30 percent = overlap, > 30 percent = TEN. SCORTEN at admission and at 72 hours predicts mortality; ≥ 3 mandates ICU-level care. DRESS (RegiSCAR criteria) requires three of: cutaneous eruption, fever > 38°C, lymphadenopathy, eosinophilia ≥ 0.7×10⁹/L or atypical lymphocytes, organ involvement (hepatic, renal, pulmonary), and HHV-6 reactivation can occur 2 to 3 weeks in. ^{[1] [2] [8]}

References12ShowHide

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