Pain and hard lump on the right side of the anus may be caused by hemorrhoids, perianal abscess and anal cancer. 1. Hemorrhoids: Hemorrhoids can lead to symptoms such as anal moisture and anal itching, and some patients may experience anal pain. If hemorrhoids appear acute thrombosis, it will lead to localized hard lumps in the anus. 2. Perianal abscess: Perianal abscess is usually caused by inflammation of the tissues around the anorectum, often caused by bacterial infection. It can cause swelling around the anus to form a hard lump, accompanied by persistent pain. If the patient’s symptoms are more serious, it may cause systemic symptoms such as fever and fatigue. 3. Anal cancer: Anal cancer will cause itching and pain around the anus in the early stage, and with the growth of cancer cells, the tumor will increase gradually, resulting in hard lumps in the anus. There may be other reasons for the pain on the right side of anus, so the patient should go to the hospital for relevant examination in time to clarify the cause of the disease, and under the guidance of professional doctors, actively treat the disease to avoid aggravation of the condition, which will bring adverse effects to the body.