The left side of the anus is swollen and painful, considering the following conditions: 1, due to perianal abscess, this situation is not much effect of drug treatment, the need for surgical incision and drainage. 2, may be due to anal fissure, is due to the relatively dry stools, discharged so that the skin around the anus by a varying degree of laceration, accompanied by a strong sense of pain, as well as a small amount of bleeding, you can use the ma yinglong hemorrhoidal ointment to apply, there is a rotting biological efficacy. 3, suffering from hemorrhoids, is due to the patient’s poor dietary habits and lead to, there will be redness and swelling around the anus, pain, as well as itching and other symptoms, you can use potassium permanganate diluted after the sitz bath, and then coated with anus tai hemorrhoidal ointment for the treatment, in conjunction with oral amoxicillin and other medications will be relieved. 4, not to rule out other perianal inflammation caused by the suggestion to go to the hospital in a timely manner for differentiation and treatment.