What causes pain inside the anus?

Pain inside the anus may be caused by various factors, mainly including the following: 1. **Proctitis**: Inflammation caused by intestinal bacterial infection, constipation, diarrhea, or other factors may lead to localized anal pain. This pain may be accompanied by changes in bowel habits, such as constipation or diarrhea. 2. **Hemorrhoids**: Hemorrhoids refer to varicose veins around the anus or rectum and may cause symptoms such as pain and bleeding. Pain may worsen during episodes of constipation or diarrhea, particularly with internal hemorrhoids or thrombosed external hemorrhoids. 3. **Anal Fissure**: An anal fissure is a tear at the opening of the anus, usually caused by trauma from passing hard stools during bowel movements, accompanied by severe anal pain. 4. **Other Factors**: Conditions such as anal sinusitis, perianal abscess, anal eczema, and malignant tumors may also cause internal anal pain. Anal sinusitis may lead to mild dull pain, while perianal abscess typically presents as persistent severe pain. If discomfort occurs, it is recommended to seek medical attention promptly for an accurate diagnosis and appropriate treatment.