Erythroderma and Chronic Lichenification Due to Metformin

We present the case of a 62-year-old man with a 4-year history of pruritus and erythroderma. The patient had been taking metformin for 5 years, so after contact allergies, contact with toxic products, and autoimmune diseases were ruled out, the condition was treated as erythroderma secondary to metformin. A skin biopsy subsequently confirmed the diagnosis and lichenification of some areas of the patient's skin. LEARNING POINTS: Erythroderma induced by drugs, even very common drugs, should be ruled out in all cases.Other causes of erythroderma should be investigated with exhaustive clinical history taking, specific tests and skin biopsy.Erythroderma should be treated as soon as possible once the cause is known.