Anal masturbation is manual erotic stimulation focusing on the anus and rectum. For humans, common methods of anal masturbation include manual stimulation of the anal opening and the insertion of an object or objects such as fingers, feet, fists, phallic shaped items, water play, or sex toys such as anal beads, butt plugs, dildos, vibrators or specially designed prostate massagers.
The most common explanation of how stimulation can be derived from anal masturbation is that the rectal opening contains many sensitive nerve endings. Other explanations include the potential for myofascial release of various pelvic floor muscles that hold significant tension for certain individuals. Orgasmic function for a male depends in part on healthy functioning of the smooth muscles surrounding the prostate, and of the pelvic floor muscles. Anal masturbation can be especially pleasurable for men because it often stimulates the prostate, which also contains sensitive nerve endings, and for women because it indirectly stimulates the G-Spot, clitoral legs, or the cervix. Some butt plugs for men are specifically shaped for prostate stimulation. Since the muscles of the anus contract during orgasm, the presence of an object holding the sphincter open can strengthen the sensation of the contractions and intensify orgasm. Some men find the quality of their orgasm to be significantly enhanced by the use of a butt plug or other anally inserted item during intercourse. At the point of orgasm, the stretching of the sphincter muscle and pressure on the prostate strengthens the sensation of contraction in much the same way as mentioned above, for females. It is not uncommon for a male to achieve orgasm through anal-prostate stimulation alone.
Enemas or anal douches can, for hygienic reasons, be taken prior to anal masturbation if desired, but they can also be a form of anal masturbation themselves: see klismaphilia. Commonly inserted objects include butt plugs, anal beads, dildos, vibrators and fingers.
Insertion of foreign objects into the anus is not without dangers. This area is fragile, the intestinal walls do not feel pain and for objects pushed too far, surgery may be necessary for removal (even without injury). Unsafe anal masturbation methods cause harm and a potential trip to the hospital emergency room. However, anal masturbation can be carried out in greater safety by ensuring that the bowel is emptied before beginning, the anus and rectum are sufficiently lubricated and relaxed throughout, and the inserted object is not of too great a size.
Some anal stimulators are purposely ribbed or have a wave pattern in order to enhance pleasure and simulate intercourse. Stimulating the rectum with a rough-edged object or a finger (for the purposes of medically stimulating a bowel movement or other reasons) may lead to rectum wall tearing, especially if the fingernail is left untrimmed. Vegetables have rough edges and most have microorganisms on the surface, and thus could lead to infection if not sanitized before use.
Minor injuries that cause some bleeding to the rectum pose measurable risk, and often need treatment. Injury can be contained by cessation of anal stimulation at any sign of injury, bleeding, or pain. While minor bleeding may stop of its own accord, individuals with serious injury, clotting problems, or other medical factors could face serious risk and require medical attention.
Prolonged or heavy bleeding can indicate a life-threatening situation, as the intestinal wall can be damaged, leading to internal injury of the peritoneal cavity and peritonitis, which can be fatal. Carefully using implements without sharp edges or rough surfaces carries a lower risk of damage to the intestinal wall.
The treatment for persistent or heavy bleeding will require a visit to an emergency room for a sigmoidoscopy and cauterization in order to prevent further loss of blood. Apart from the volume of blood that is lost into the rectum, other easily observable indications that medical intervention is urgently needed as a result of blood loss are an elevated heart rate, a general feeling of faintness or weakness, and a loss of pleasure from the act.
Butt plugs normally have a flared base to prevent complete insertion and should be carefully sanitized before and after use. Sex toys, including objects for rectal insertion, should not be shared in order to minimize the risk of disease. Objects such as lightbulbs or anything breakable such as glass or wax candles cannot safely be used in anal masturbation, as they may break or shatter, causing highly dangerous medical situations.
Some objects can become lodged above the lower colon and could be seriously difficult to remove. Such foreign bodies should not be allowed to remain in place. Medical help should be sought if the object does not emerge on its own. Immediate assistance is recommended if the object is not a proper rectal toy, like a plug or something soft, for example if it is either too hard, too large, has projections, slightly sharp edges, or if any trace of injury happens (bleeding, pain, cramps). Small objects with dimensions similar to small stools are less likely to become lodged than medium-sized or large objects as they can usually be expelled by forcing a bowel movement. It is always safest if a graspable part of the object remains outside the body.
The biological function of the anus is to expel intestinal gas and feces from the body; therefore, when engaging in anal masturbation, hygiene is important. One may wish to cover butt plugs or other objects with a condom before insertion and then dispose of the condom afterwards. To minimize the potential transfer of germs between sexual partners, there are practices of safe sex recommended by healthcare professionals. Oral or vaginal infection may occur similarly to penile anus-to-mouth or anilingus practices.