Proctitis is an infection that causes inflammation and bleeding in the rectum. STDs are a possible cause of proctitis, but not the only cause of it. Proctitis can last a short time or become a chronic condition (last for weeks or months or longer). Colitis is also infectious, but generally is more extensive (can include all or bigger sections of the large intestine) than proctitis which is limited to just the rectum.
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www.m.webmd.com/a-to-z-guides/proctitisMost of us here have ulcerative colitis, a chronic lifelong illness caused by the immune system. A different sorta thing entirely...