The possible causes of pain inside the anus include the following: first, hemorrhoids: the pain is more common among clinics due to internal hemorrhoids or thrombosed external hemorrhoids, which are sometimes more intense, especially when constipation or frequent diarrhea occurs. Second, anal fissure or anal papillomegaly: pain inside the anus is not excepted due to anal fissure or anal papillomegaly, which can cause irritating pain especially in patients who are often constipated or drink alcohol. Third, anal eczema and malignant tumors: eczema or malignant tumors inside the rectum and anus can cause pain in this area. Therefore, it is best to go to the hospital in time for pain inside the anus, find the cause, find the cause of the pain, and choose the appropriate treatment according to the cause.