Causes

Several diseases and conditions can cause inflammation of the rectal lining. They include:

• Inflammatory bowel disease. About 30% of people with inflammatory bowel disease (Crohn's disease or ulcerative colitis) have inflammation of the rectum.
• Infections. Sexually transmitted infections, spread particularly by people who engage in anal intercourse, can result in proctitis. Sexually transmitted infections that can cause proctitis include gonorrhea, genital herpes and chlamydia. Infections associated with foodborne illness, such as salmonella, shigella and campylobacter infections, also can cause proctitis.
• Radiation therapy for cancer. Radiation therapy directed at your rectum or nearby areas, such as the prostate, can cause rectal inflammation. Radiation proctitis can begin during radiation treatment and last for a few months after treatment. Or it can occur years after treatment.
• Antibiotics. Sometimes antibiotics used to treat an infection can kill helpful bacteria in the bowels, allowing the harmful Clostridium difficile bacteria to grow in the rectum.
• Diversion proctitis. Proctitis can occur in people following some types of colon surgery in which the passage of stool is diverted from the rectum to a surgically created opening (stoma).
• Food protein-induced proctitis. This can occur in infants who drink either cow's milk- or soy-based formula. Infants breast-fed by mothers who eat dairy products also may develop proctitis.
• Eosinophilic proctitis. This condition occurs when a type of white blood cell (eosinophil) builds up in the lining of the rectum. Eosinophilic proctitis affects only children younger than 2.