The anal sinus is located at the junction of the rectal mucosa and the skin of the anal canal, and is a small crypt between the anal columns after the anal flap. There are six to eight human anal sinuses, funnel-shaped, and about half of them have ducts at the bottom connected to the anal glands, which have the function of storing mucus to lubricate the stool. Because the opening of the anal sinus is upward, it often accumulates fecal residue, and when constipation, diarrhea, or alcoholism, spicy food, the mucous membrane of the anal sinus is easily damaged, congested, and local resistance is reduced, thus causing anal sinusitis. The symptoms of anal sinusitis mainly include anal discomfort, moist itching, occasional stinging or burning pain, often a little mucus or bloody discharge during defecation, and physical examination can reveal a tight anal canal, congested anal sinus mucosa, and purulent or bloody discharge. Because of the atypical symptoms and the special location of its onset, it is often not taken seriously by patients. If sinusitis is not treated in time, on the one hand, the inflammation can spread to the adjacent anal papillae, causing inflammatory hyperplasia and anal papilloma; on the other hand, the inflammation spreads to the anal glands through the bottom duct, and the inflammation can easily spread to the perirectal space and cause abscesses and anal fistulas after the infection of the anal glands. It can be said that sinusitis is the root cause of secondary perianal diseases. You can prevent sinusitis by eating more fruits and vegetables, avoiding alcohol abuse, and keeping your stools soft and smooth. Once you suffer from anal sinusitis, in addition to paying attention to your diet, you can take internal Chinese medicine to clear heat and remove dampness and detoxification (Wu Wei Disinfection Drink or Huang Lian Detoxification Tang), and with local sitz baths, hemorrhoid suppositories or hemorrhoid cream plugged into the anus. If medication does not work, the inflammation develops or there is a hidden fistula, surgery is required.