Hello,
Causes of itchy anal rash include moisture(due to sweating or frequent washing), the abrasion caused by clothing,the pressure of sitting,chemical irritants like laundry soaps, colognes and scented toilet paper,certain food irritants,medicines like some antibiotics and laxatives,infections like STD’s and pinworms,anal abrasions
and fissures
and skin problems such as psoriasis, seborrhea
and eczema. Sometimes hemorrhoids will start off as red rash and anal itching.