New rash
at the bedside
- airway, breathing, circulation; full vitals including temperature
- look everywhere → whole skin, eyes, mouth, genitals
- drug timeline → every drug started in the last 8 weeks, with start dates
escalate now if
- wheeze, stridor, low BP, lip or tongue swelling → anaphylaxis → allergic reaction
- blisters, skin that peels or slides, painful skin, sores in two or more mucosal sites → SJS / TEN, dermatology now
- fever, facial swelling, widespread rash, nodes, eosinophils or rising LFT or creatinine → DRESS
- non-blanching purpura with fever or unwell → sepsis until proven otherwise, antibiotics now
- red, hot, pain out of proportion, crepitus → necrotizing infection, surgery now
differentials
- morbilliform drug eruption → the commonest; itchy pink spots, trunk to limbs, usually days 4–9, no mucosa, patient well
- urticaria → wheals within minutes to hours → allergic reaction
- SJS / TEN → days 4–28; fever first, dusky or target spots, blisters, mucosal erosions
- DRESS → weeks 2–6; fever, facial edema, eosinophilia, liver or kidney injury; allopurinol, carbamazepine, phenytoin, lamotrigine, vancomycin, sulfonamides
- pustules → many small pustules on red skin within days of an antibiotic: AGEP
- not a drug → viral rash, zoster, cellulitis, contact dermatitis, scabies, vasculitis (palpable purpura)
focused check
- symptoms → itch or pain, fever, sore eyes, mouth or genital sores
- drug chart → antibiotics, allopurinol, anticonvulsants, NSAIDs, contrast; first dose dates
- exam → blanching or not, blisters, skin sliding with gentle sideways pressure, nodes, face swelling, how much skin
send now
- CBC with differential → eosinophils, platelets
- LFT, RFT, CRP → organ involvement (DRESS)
- purpura → cultures, coagulation, urinalysis
- photo → in the record, with consent, to compare tomorrow
treat
mild, patient well
- stop the likely drug if there is an alternative; discuss with the team if it is essential
- emollient; cetirizine 10 mg PO daily for itch; topical steroid to the body, not the face
- review tomorrow: new blisters, mucosa, fever → call back now
SJS / TEN
- stop every non-essential drug started in the last 8 weeks
- dermatology now; ophthalmology early; extensive skin loss → ICU or burns unit
- fluids, analgesia, eye and mouth care; no systemic steroids from the call
DRESS
- stop the culprit; dermatology; LFT, creatinine and eosinophils daily
- steroids are a specialist decision
purpura
- unwell or febrile → cultures, antibiotics now → fever
- low platelets → platelet drop; palpable with blood in the urine → vasculitis, creatinine, nephrology
- allergy record → drug, reaction, date; never rechallenge after SJS, TEN or DRESS
- hand over → drug stopped, mucosa and skin findings, bloods due, escalation trigger
evidence
Verify indication, dose, allergies, interactions, renal/hepatic function and local protocols before prescribing.
free the on-call checklist covers the whole shift on one printable page.
studying for the IM exam? the IM Rapid Review covers this in the same format. see the sample chapter.
updated Oct 2026file complaint/new-rash