The first reason is that the patient does not pay attention to personal hygiene in life, does not bathe or clean behind the ear frequently, and sometimes rubs it with his hands, which may lead to bacterial infections behind the ear, so the symptoms of pus may appear. Secondly, the main consideration is that the patient has an oily skin type, which is particularly prone to blockage of the sebaceous glands. Sometimes patients are younger, have a high metabolism, and the sebaceous glands themselves will secrete vigorously, so they are especially prone to growing pustules. Patients are advised to pay attention to hygiene and also to avoid always touching the back of the ear with their hands. If it is caused by clogged sebaceous glands, patients are advised to apply Bactrim ointment behind the ears. If there is still no improvement, patients are advised to consider surgical removal.