Scarring on the forehead of a 50 year old male patient after using efudix medication for solar keratoses. Solar keratoses are dry, scaly patches of skin that have been damaged by the sun. Its not usually serious, but there is chance the patches could develop into skin cancer. Efudix topical cream destroys cancerous and pre-cancerous cells. The most common side effects are redness, scarring, scaling, crusting and swelling.