Erythema nodosum leprosum is defined by the appearance of tender skin nodules, which can be accompanied by fever, joint pain, neuritis, edema, malaise and/or lymphadenopathy. The authors describe the case of a 19-year-old Angolan black woman, resident in Portugal for the last 10 years, diagnosed with Hansen's disease at the age of 12, irregular with follow-up and non-compliant with treatment. She was referred to our clinic with painful nodules and pustules on the upper limbs, diffuse facial infiltration with pustules and fever, after initiating minocycline with the intention of treating acne. Diagnosis of erythema nodosum leprosum was confirmed by the presence of acid-fast bacilli in the skin smear and also in skin biopsy. Minocycline was suspended and the patient was treated with systemic steroids, with prompt clinical improvement. Our case is reported to alert clinicians to this unusual presentation of erythema nodosum leprosum in a patient treated with highly bactericidal drugs that were not intended to treat Hansen's disease.