Why does the anus become very painful after having diarrhea multiple times?

Diarrhea, commonly referred to as "having loose bowels," often causes anal pain after frequent bowel movements. This discomfort may result from irritation of the anus, anal muscle fatigue, proctitis, hemorrhoids, anal fissures, or other conditions. It is recommended to seek medical attention promptly, identify the underlying cause, and receive appropriate treatment under the guidance of a healthcare professional. Specific explanations are as follows:

1. Anal Irritation: During diarrhea, increased frequency of bowel movements can lead to repeated friction and irritation of the anus. This mechanical stimulation may make the skin around the anal area sensitive and painful. It is advisable to gently clean the anal area with warm water after each bowel movement to help reduce irritation.

2. Anal Muscle Fatigue: Frequent defecation can overwork the anal muscles, leading to muscle fatigue and pain. Avoid prolonged sitting or standing, allow the anal muscles adequate rest, and consider performing relaxation exercises such as Kegel (pelvic floor) exercises to aid muscle recovery.

3. Proctitis: During diarrhea, bacteria, viruses, and other microorganisms in feces may infect the anal region, potentially causing proctitis. Common symptoms include redness, swelling, pain, and itching around the anus. Patients should follow medical advice and use medications such as cefdinir dispersible tablets, amoxicillin dispersible tablets, or potassium permanganate topical tablets as prescribed.

4. Hemorrhoids: Chronic diarrhea may lead to varicose veins in the anus, resulting in hemorrhoids. Hemorrhoids can be compressed during bowel movements, causing anal pain. Patients should use medications such as Ma Yinglong Musk Hemorrhoid Ointment, Huaijiao Pills, or Huazhi Tablets as directed by a physician.

5. Anal Fissure: Increased pressure on the anus during diarrhea may cause tears or cracks in the anal lining, leading to severe pain and bleeding. Patients should follow medical instructions and apply treatments such as bear bile hemorrhoid ointment, Longzhu ointment, or glyceryl trinitrate ointment.

In daily life, patients are advised to wear cotton underwear, change it frequently, maintain good local hygiene, and avoid spicy and irritating foods such as chili peppers and Sichuan pepper, all of which can support recovery.