These rare but horrible skin conditions may begin with a 1-2 days of fever and discomfort. Unusual skin pain, or muscle pain out of proportion to the aches of a virus, should alert us. There may be early signs of painful rash: blisters or sunburn-like reddening (not itching). Blisters may occur inside the mouth and eyes; women may have vaginal burning. One key sign may be present: rubbing apparently-normal skin makes it peel off (Nikolsky’s sign).
Stevens-Johnson & TEN are pretty much the same disease. The cause is often a medication: maybe for Gout (allopurinol), Seizures (phenobarbitol, Dilantin®, carbamazepine, lamotrigine), or sulfa antibiotics. Viruses or Mycoplasma (“walking pneumonia”) can also be triggers.
Fever plus widespread skin pain and/or sunburn-like rash is very concerning, especially if there are any blisters (and the patient hadn’t been anywhere to get a real sunburn). Blisters in eyes, mouth, or vagina make the diagnosis definite. Patients often need treatment in specialty ICUs that handle burns. Mortality can be up to 30%. If you can handle disturbing pictures, Google-image the diseases.