When a cause can be found, the itching is usually due to irritation of the skin around the anus. Some of the most common irritants Perfumes, chemicals, or dye on toilet paper. These can also cause an allergic reaction. Moisture from sweat or diarrhea may cause itching. If the anal skin stays wet, the skin begins to break down.
Some foods irritate the anus when they are expelled during a bowel movement.
The most common culprits are caffeine, chocolate, beer, nuts, diary products, and spicy food. Infections such as pinworms, yeast, or genital warts can cause itching. Hemorrhoids , which cause painful swelling of blood vessels in the anal area, can cause itching. Cancer, in rare instances, may be a cause. The most common symptom is itching especially at night and after a bowel movement.