Anal sex can expose its participants to two principal dangers: infections due to the high number of infectious microorganisms not found elsewhere on the body, and physical damage to the anus and rectum due to their fragility. Unprotected penile-anal penetration, colloquially known as barebacking, carries a higher risk of passing on sexually transmitted infections (STIs/STDs) because the anal sphincter is a delicate, easily torn tissue that can provide an entry for pathogens. The high concentration of white blood cells around the rectum, together with the risk of tearing and the colon's function to absorb fluid, are what place those who engage in anal sex at high risk of STIs. Use of condoms, ample lubrication to reduce the risk of tearing, and safer sex practices in general, reduce the risk of STI transmission. However, a condom can break or otherwise come off during anal sex, and this is more likely to happen with anal sex than with other sex acts because of the tightness of the anal sphincters during friction.
In addition to nerve endings, pleasure from anal intercourse may be aided by the close proximity between the anus and the prostate for males, and vagina, clitoral legs and anal area for females. This is because of indirect stimulation of the prostate and vagina or clitoral legs. For a male insertive partner, the tightness of the anus can be a source of pleasure via the tactile pressure on the penis. Pleasure from the anus can also be achieved through anal masturbation, fingering, facesitting, anilingus, and other penetrative and non-penetrative acts. Anal stretching or fisting is pleasurable for some, but it poses a more serious threat of damage due to the deliberate stretching of the anal and rectal tissues; its injuries include anal sphincter lacerations and rectal and sigmoid colon (rectosigmoid) perforation, which might result in death. Lubricant and condoms are widely regarded as a necessity while performing anal sex as well as a slow and cautious penetration.
The tissue and skin around the anus acts as a protective barrier for the bottom half of your digestive tract. However, the tissue inside the anus is thinner, delicate, and more likely to tear and bleed as a result of penetration. This increases the likelihood of passing infections, viruses, or bacteria between partners. Even two partners who don’t have any sexually transmitted infections (STIs) can still pass bacteria between each other through these tears in the skin.