Testosterone is a hormone that is produced in large amounts in the testes of men, in small amounts in the ovaries of women and also in small amounts in the adrenal glands of both men and women. Testosterone is responsible for the development of many of the male sexual characteristics, including the external genitalia, facial hair and increased muscle mass. Several chemicals can stop the production of testosterone, including prescription medications and other more commonly available substances.

Prescription drugs known as LHRH agonists stop the production of testosterone by interfering with the hormone LHRH, which stands for luteinizing-hormone-releasing hormone. LHRH is also sometime known as gonadotropin-releasing hormone, abbreviated GnRH. LHRH causes luteinizing hormone, or LH, to be secreted from the pituitary gland. LH then stimulates the testes to produce testosterone, explains the Fox Chase Cancer Center. Blocking the action of LHRH causes the pituitary gland to produce less LH, resulting in reduced production of testosterone. High levels of LHRH agonists have the same effects as surgically removing the testicles, and for this reason, treatment with LHRH is sometimes called chemical castration. LHRH agonists are sold under the brand names Zoladex and Lupron.

Anabolic steroids are compounds that mimic the activity of naturally occurring testosterone. For this reason, anabolic steroids, which are also known as anabolic-androgenic steroids, are sometimes abused by athletes seeking to increase their muscle mass and boost athletic performance. Use of anabolic steroids often leads to decreased blood levels of testosterone, reports the United States Department of Health and Human Services. Doctors suspect this occurs because the anabolic steroids act like normal testosterone and trick the body into thinking it does not need to produce more testosterone.

Several studies have found that consumption of alcohol reduces synthesis of testosterone in the body, according to the National Institute on Alcohol Abuse and Alcoholism. Doctors do not yet fully understand why alcohol has this inhibitory effect on testosterone biosynthesis. Current research suggests that alcohol inhibits one more more steps of the biochemical pathway that produces testosterone.

A medication called ketoconazole is sometimes used to treat fungal infections. Studies have found that ketoconazole inhibits the production of testosterone in men, explains an article in the Journal of Pharmacobio-Dynamics. One part of the ketoconazole drug called imidazole inhibits the biochemical pathway that leads to the production of testosterone.