There are many causes of proctitis but they can be broken down into several small groups:
- sexually-transmitted diseases
- non-sexually transmitted infection
- autoimmune disease
- noxious agents
Sexual disease related proctitis occurs with high frequency among homosexual men and women who engage in anal intercourse. Sexually-transmitted diseases which can cause proctitis include gonorrhoea, herpes, chlamydia etc. Amoebiasis is another disease which can cause proctitis and can be transmitted by ano-oral sex.
Non-sexually transmitted infections causing proctitis are seen less frequently than STD proctitis. Non-sexually transmitted infection occurs in children and the proctitis is caused by beta-haemolytic streptococcus, the same organism which causes strep throat. Autoimmune proctitis is associated with diseases such as ulcerative colitis or Crohn's disease.
Proctitis may also be caused by physical agents including chemicals inserted into the rectum, medications and radiation. Radiation proctitis is seen in association with radiotherapy as part of cancer treatment.
Risk factors include high-risk sexual practices, homosexuality, and autoimmune disorders. In ulcerative proctitis, a common form of proctitis, ulcers appear in the inflamed rectal lining. The condition may affect 1 to 4 inches of the lower rectum.