Hello, Anal itching can be caused by irritating chemicals in the foods we eat, such as are found in spices, hot sauces, and peppers. Other common causes like pinworms,hemorrhoids, tears of the anal skin (fissures), and skin tags (abnormal local growth of anal skin). Anal itching also can be caused by the irritation of continuous moisture in the anus from frequent liquid stools, diarrhea, or escape of small amount of stool (incontinence), a yeast infection , Psoriasis can irritate the anus, fistula, please consult a general surgeon first to know the cause.