DRESS (drug hypersensitivity syndrome)
Also called drug reaction with eosinophilia and systemic symptoms, DIHS
The slow-burning severe drug reaction: two to eight weeks after the culprit starts, a widespread eruption arrives with facial edema, fever, lymphadenopathy, eosinophilia, and an organ on fire, most often the liver. The latency is the trap: the drug feels too old to blame.
How it looks
A confluent morbilliform-to-infiltrated eruption over most of the body surface with striking centrofacial edema, fever, and lymphadenopathy.
Rose is the lesion, grey the pattern the lesions make, green where on the body it lives.
Across skin tones
The confluent erythema is easily underestimated in deeply pigmented skin, reading violaceous or dusky rather than red; facial edema, skin infiltration you can feel, fever, and the laboratory picture must be weighted accordingly.
Don't miss
Allopurinol started for an incidental urate two months ago is the classic missed culprit; a drug's innocence is not established by its age.
Symptoms & course
- Fever and malaise out of keeping with a 'simple' drug rash
- Facial, especially periorbital, edema
- The rash desquamates and smoulders for weeks even after the drug stops
Diagnostic approach
- FBC with eosinophils and atypical lymphocytes, LFTs, renal function, urinalysis
- The drug timeline, 2-8 weeks back: aromatic anticonvulsants, allopurinol, sulfonamides, vancomycin, minocycline
- HHV-6 reactivation supports it; RegiSCAR criteria organize it
Differential, and how to separate them
- Morbilliform drug eruption
Favours it: A widespread drug exanthem
Against it: Simple exanthems come in week one, spare the face, and bring no fever, edema, eosinophilia, or organ injury
- Stevens–Johnson syndrome / toxic epidermal necrolysis
Favours it: A severe drug reaction with systemic illness
Against it: SJS/TEN targets mucosa and detaches epidermis with skin pain; DRESS infiltrates and swells but keeps the surface
Management principles
- Stop the culprit and every relative of it
- Systemic corticosteroids, tapered over weeks to months, for significant organ involvement; relapse on rapid taper is characteristic
- Monitor long after discharge: autoimmune thyroiditis arrives months later
Clinical pearl: Face swollen, drug started six weeks ago, eosinophils up: that triad is DRESS, and the rash's exact morphology matters far less than the company it keeps.
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