Hypersensitivity reaction with metformin: a case report

Metformin is a biguanide derivative widely used for treatment of diabetic patients. The most common toxic effects of metformin are gastrointestinal (anorexia, nausea, vomiting, abdominal discomfort and diarrhoea). As with other drugs, allergic reactions can occur with metformin also, but these are very rare. A case of hypersensitivity reaction with metformin was reported in adverse drug monitoring centre. A 59-year-old female, newly diagnosed case of diabetes mellitus II, started on metformin tablet 500 mg twice daily, developed purpuric skin lesions on her arms, legs and back few days after starting the drug. metformin was stopped and patient was put on glimepiride tablet. The lesions slowly started subsiding after stopping metformin.