A 41-year-old woman presented to because of the sudden appearance of erosions on and swelling of her lips. On clinical examination, diffuse erythema of the labial mucosae with small vesicles and crusted erosions on both the superior and inferior vermillion borders were noted.
Further inspection of her mouth showed erythema and erosions on the inner cheek and mild focal desquamated gingivitis. The patient was otherwise healthy, with good oral hygiene. No other lesions were seen on the rest of her body.
She had been taking paracetamol and amoxicillin for 3 days for a sore throat and fever. Based on the clinical symptoms and medical history, she was diagnosed with erythema multiforme (EM) major. She was treated with prednisolone 60 mg/day, with dramatic improvement of her symptoms.