Bob is a three year old boy who has been brought to see you by his mother Gertrude. Gertrude explained that for the last three days Bob has been complaining he is itchy down below. She has noticed him itching his groin and said that he was crying when passing urine this morning. She is not aware of any other systemic symptoms. Examination reveals erythema and swelling of the glans penis and foreskin. You explain to his mother that the likely diagnosis is non-specific dermatitis.
Which of the following is the most appropriate first line treatment?