Robert Micheletti, MD focuses on the key points from his lecture Dermatologic Emergencies on Saturday, November 5, 2022 at the PA/NP Elevate-Derm Conference in Tucson, Arizona.

In this video

In conversation with dermatology nurse practitioner Veronica Richardson, Dr. Micheletti explains why SJS/TEN — though rare at not quite 10 per million per year — carries "an outsized footprint when it comes to litigation," almost always because of a failure to diagnose and refer in time. He describes the classic picture: a flu-like prodrome, a clinically unwell patient with photophobia, skin tenderness and mucous membrane involvement, and the "dusky atypical target lesion" — erythema turning purplish in the center, "the color of unhappy, unhealthy skin" that will blister and slough. The usual culprits are medications — beta-lactams, sulfa drugs like trimethoprim-sulfamethoxazole, antiepileptics such as carbamazepine, phenytoin and lamotrigine, and allopurinol — typically introduced one to three weeks earlier, with a median around 12 to 14 days.

He then contrasts SJS/TEN with DRESS (drug reaction with eosinophilia and systemic symptoms), which is more common at roughly one in 1,000 to one in 10,000 exposures and presents as a systemic hypersensitivity reaction: a morbilliform, deep-red rash with facial involvement and swelling, fever, lymphadenopathy, and eosinophilia with liver and renal abnormalities. The catch, he notes, is the longer latency — weeks to months — which makes DRESS easy to miss because clinicians aren't suspecting a drug the patient has already tolerated for months. He and Richardson stress going beyond the visible medication list to ask about over-the-counter drugs, as-needed NSAIDs, and recent dose increases.

  • Suspect SJS/TEN in a patient with a flu-like prodrome who feels unwell and has photophobia, skin tenderness, mucous membrane involvement, and dusky atypical target lesions that blister and slough — "there's not much downside" to urgent further evaluation.
  • The most common SJS/TEN triggers are medications: beta-lactam and sulfa antibiotics, antiepileptics (carbamazepine, phenytoin, lamotrigine), and allopurinol.
  • Onset for SJS/TEN typically runs one to three weeks after starting the drug, with a median of 12–14 days; a drug taken longer than eight weeks is an unlikely trigger, though dose increases can still provoke a reaction via metabolite buildup.
  • Go beyond the medication list on the chart — ask about over-the-counter drugs and as-needed NSAIDs, since roughly a sixth of patients have already stopped the culprit drug by the time they're evaluated.
  • DRESS is a systemic hypersensitivity reaction with a longer latency (weeks to months), a morbilliform facial rash, facial swelling, fever, lymphadenopathy, eosinophilia, and liver/renal abnormalities — the organ involvement is what makes it dangerous and easy to overlook.