Receivers of anal sex can develop bowl problems over the long-term and develop hemmoroids and anal fissures. It isn't stress free for sure. The gay male community is most educated about the potential problems and how to avoid them. Good luck!

First - anatomy. At the lower end of the bowel, there are two distinct circular bands of muscles, sphincters, one is located about an 1 ½" above the other. These clamp down tight to prevent the passage of feces or gas. The mucous membrane lining of the rectum is not as heavy as the lining of the vagina, so it can tear quite easily and it does not heal as quickly as the vagina. Because feces, loaded with bacteria, are passing by, any tear is vulnerable to infection. The vigorous thrusting that may occur during anal intercourse can tear the mucous membrane. This can develop into an anal abscess that can become infected - more about that in a moment. Also, if your partner has any of the sexually transmitted infections (STI's), then you could get infected through the tear. So we are talking about gonorrhea (treatable); venereal warts (treatable if external, difficult if up in the rectum); syphilis (treatable); herpes (treatment, no cure); yeast infection (treatable); and HIV and AIDS (treatment but no cure.) You do not want any of these STI's. A “fissure” is a tear up in the rectum can develop into a crack, and become infected. It can gradually extend out through the wall of the bowel and form a channel across, through and into a nearby organ. That's called a "fistula", and it would allow feces to flow from the rectum into the vagina and out. Repairing tears, fissures and fistulas is delicate surgery and recovery can be long and painful.

there is always the danger of getting poop on your pecker.(that is if your the packer,rather than the packee).