Anal sensation of crawling insects, known clinically as anal itching, is an itching of the skin around the anus, but there is no other primary skin injury. It occurs mostly in people aged 20-40 years old, with a higher incidence in men than in women, and is more likely to occur in people who are sedentary and do not like to move around. The causes are: 1, eating spicy and irritating foods, such as chili, tobacco, alcohol, coffee, etc. These foods can stimulate the anal canal and anal skin, resulting in perianal skin itching. 2, allergic reactions, such people are mostly allergic, with a history of previous allergies, and a history of allergen exposure before the symptoms of anal itching. 3, perianal skin fungal, viral infections, common infections such as S. epidermidis. 4, hemorrhoids, anal fissures 5. itching around the anus due to local inflammatory exudation, forming eczema-like changes. 5. pinworm infection, mostly seen with children. 6. mental overexcitement, depression, neurasthenia, addiction, etc.