What could cause pain in anus?

Several causes. Anal pain can be a lot of problems. Anal fissures, abscess, inflammatory bowel disease, henorrhoids, constipation are a few of the causes. Other types of infections are possible. A good history and exam is needed to really diagnose this problem.
Anal pain. The most common cause of pain in the anus is a simple hemorrhoid, often with a tender bluish nodule palpable. Other causes are an anal fissure (tear in the side of the anus due to constipation), inflamation of the anus (proctitis), which can be a feature of inflammatory bowel disease or of some infections (notably stds like gonorrhea or herpes). Sometimes a prostate infection will cause anal pain.

Related Questions

What could cause pain in the anus after sneezing?

Couple of things. Hemorrhoids and fissure both come to mind. More likely the first. There are other possibilities as well. I'd suggest seeing your doctor to have it checked out. Read more...