dermatology

DRESS

Drug Reaction with Eosinophilia and Systemic Symptoms. A widespread rash with fever, facial oedema, lymphadenopathy, eosinophilia and organ involvement — most often the liver — appearing 2 to 8 weeks after starting the culprit drug. The latency is…

Stop the drug — rash, fever, eosinophilia, organs

The pathway

1 · Think of it in any rash with fever and a new-ish drug

2–8 weeks after starting the drug — not days
Usual culprits: allopurinol, lamotrigine, carbamazepine, phenytoin, sulfonamides, vancomycin, minocycline, dapsone
Facial oedema is characteristic and often mistaken for fluid overload or angioedema
Widespread morbilliform rash, often becoming confluent, sometimes over 50% of the body

2 · Bloods tell you it is systemic

FBC — eosinophilia, and atypical lymphocytes
LFTs — hepatitis is the commonest organ involvement
U&E — interstitial nephritis
CK, troponin, TFTs — myocarditis and thyroiditis are recognised, thyroiditis often late
CRP, blood cultures — because the differential is sepsis

3 · Stop the culprit drug

Stop it now. If several are possible, stop all non-essential candidates
Do not rechallenge, ever — and document it as a serious allergy
Cross-reactivity matters: the aromatic anticonvulsants (carbamazepine, phenytoin, lamotrigine, phenobarbital) cross-react with each other

4 · Distinguish it from SJS/TEN and from sepsis

SJS/TEN: painful skin, mucosal involvement, Nikolsky positive, skin detachment — a different emergency
Sepsis: cultures, and treat if you cannot exclude it — but a rising eosinophil count points away
Acute generalised exanthematous pustulosis: pustules, faster onset, milder
Use the RegiSCAR criteria if you want a formal score

5 · Treat

Dermatology involvement — this is their disease
Systemic corticosteroids where severity and organ involvement indicate them — a specialist-led decision
Typically prednisolone 0.5–1 mg/kg/day, weaned slowly over at least several weeks and often months, depending on severity and organ involvement; rapid withdrawal causes relapse
Topical steroids and emollients for skin-limited disease
Supportive: fluids, temperature, nutrition — the skin is a failing barrier

6 · Follow it up, because it is not over

Relapses occur weeks after stopping the drug and after steroid reduction
Thyroid function at convalescent follow-up, around 2–3 months — autoimmune thyroiditis is a recognised late complication. One normal result does not complete follow-up; symptoms later still warrant retesting
Explain the diagnosis and the drug to the patient in writing — they must avoid it and its relatives for life

Drugs

Drug	Dose	Route	Notes
Prednisolone	0.5–1 mg/kg/day, weaned over months	PO	For significant organ involvement, where systemic steroids are indicated — a specialist, severity-dependent decision. The taper runs to roughly 6 weeks to 3 months in mild or moderate disease and 3 to 6 months in severe DRESS; rapid withdrawal causes relapse.
Topical corticosteroid	Potent, per dermatology	Topical	Skin-limited disease. Emollients alongside.
The culprit drug	STOP	—	Allopurinol, lamotrigine, carbamazepine, phenytoin, sulfonamides, vancomycin, minocycline, dapsone. Aromatic anticonvulsants cross-react with each other.

When to escalate

Mucosal involvement, skin pain or Nikolsky positive — this is SJS/TEN, not DRESS,Deranged LFTs with a rising bilirubin or coagulopathy — hepatology, this can progress to liver failure,Hypotension, arrhythmia or a raised troponin — myocarditis; cardiology and critical care,Not improving after stopping the drug — dermatology and a review of what else is on the chart

Reference: British Association of Dermatologists guidance on severe cutaneous adverse reactions; RegiSCAR diagnostic criteria for DRESS. Specialist dermatology input is expected.

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