What causes red itchy bum hole?

Pruritis Ani: Pruritus ani is the irritation of the skin at the exit of the rectum, known as the anus, causing the desire to scratch. The intensity of anal itching increases from moisture, pressure, and rubbing caused by clothing and sitting. It can also be caused by intestinal parasites, frequent liquid stools, diarrhea, residual stool deposits, or the escape of small amounts of stool as a result of incontinence or flatulence, hemorrhoids, and many rashes, as well as a yeast infection or Candidiasis. Hope this helps.

Most commonly hemorrhoidal disease: Another fairly common problem, although more and children, his pinworms. Pinworms are little parasites that come out of the anal orifice at nighttime and cause local irritation and itching.