A 62-year-old man, in polimiositis treatment for 12 years with immunotherapy, was admitted to hospital to investigate a complaint of high fever for the past three days. Fifteen days before, he suffered a traumatic subdural hematoma surgery removal,after which he started to use antiepileptic drugs. Different cultures were prepared in blood, secretions, and liquor to identify an infectious agent. Despite no positivity, some antibiotics were introduced. On the eleventh day, he presented multiple ulcers in mouth and lips associated to white plaques, suggesting candidosis, dry and erithematous eyes, and exantema on the body. Fever was still present. Stevens Jonhson's Syndrome was diagnosed based on clinical signs. The antiepileptics drugs were changed and antibioticotherapy discontinued; only symptomatic treatment was maintained and corticoids were introduced. The course was favourable ten days later, and the patient was released. Polypharmacy can lead to adverse drug reactions. A 62-year-old man, in polimiositis treatment for 12 years with immunotherapy, was admitted to hospital to investigate a complaint of high fever for the past three days. Fifteen days before, he suffered a traumatic subdural hematoma surgery removal,after which he started to use antiepileptic drugs. Different cultures were prepared in blood, secretions, and liquor to identify an infectious agent. Despite no positivity, some antibiotics were introduced. On the eleventh day, he presented multiple ulcers in mouth and lips associated to white plaques, suggesting candidosis, dry and erithematous eyes, and exantema on the body. Fever was still present. Stevens Jonhson's Syndrome was diagnosed based on clinical signs. The antiepileptics drugs were changed and antibioticotherapy discontinued; only symptomatic treatment was maintained and corticoids were introduced. The course was favourable ten days later, and the patient was released. Polypharmacy can lead to adverse drug reactions.