Mixed hemorrhoid surgery 20 days after the anus is very itchy, may be the skin mucous membrane healing, infection, eczema, allergies and so on. 1. Skin and mucous membrane healing: 20 days after surgery, the skin and mucous membrane has healed, at this time the subcutaneous nerve tissue growth, there will be obvious itching discomfort, you can cold compress to relieve the symptoms. 2. Infection: poor wound healing after surgery, the wound is contaminated by feces, it is easy to bacterial infection, redness, swelling, itching, and even pain. 3. Eczema: surgical wounds in the process of healing, there may be secretions, digestive fluids to stimulate the anus, repeated stimulation of the local formation of eczema, there will also be itching, red rash. 4. Allergy: If you wear new clothes or contact with special items, it is easy to cause allergies, there will also be itching. Usually pay attention to do a good job of anal cleanliness and hygiene, keep the bowel movement, the emergence of uncomfortable symptoms, serious and timely to the hospital, to identify the causes of treatment.