Egyptian and Indian medicine men recommend testis tissue as an aphrodisiac and to treat erectile dysfunction. Greek athletes use performance-enhancing remedies, including testicular extracts.




German scientist Arnold Berthold surgically removes testes from juvenile roosters, which then fail to develop distinctive plumage and show no interest in hens. Reimplanting the testes reverses these deficits. Berthold suspects that the testes secrete a substance into the blood that promotes masculine characteristics.




French physiologist Charles-Edouard Brown-Sequard, age 72, injects himself with an extract made from dog and guinea pig testicles. He reports that the therapy increases his strength, sharpens his wits, relieves constipation and lengthens the arc of his urine stream. Physicians soon begin using testicular extracts to treat a variety of conditions, including diabetes, arteriosclerosis, epilepsy, hysteria and gangrene.




After injecting themselves with liquid derived from bull testicles, Oskar Zoth and fellow Austrian scientist Fritz Pregl, a future Nobel Prize winner, determine that the extract increases muscle strength. (Curiously, they measure strength changes in their middle fingers to reach this conclusion.)




Viennese physiologist Eugen Steinach introduces an operation in which the vas deferens is tied, claiming that the procedure rejuvenates aging males by redistributing sperm into the body. Alleged benefits include hair growth and better erections. Sigmund Freud and William Butler Yeats later undergo the surgery.



A team of scientists backed by a Dutch pharmaceutical firm identifies testosterone, a male hormone produced by the testes. Later that year, two chemists working separately—Adolf Butenandt in Germany, and Leopold Ruži?ka in Switzerland—report a week apart that they have synthesized testosterone. Butenandt and Ruži?ka later share the 1939 Nobel Prize in chemistry for their work on sex hormones.



Late 1930s

Doctors begin experimenting with testosterone injections for treating hypogonadism (inadequate testosterone production by the testes) and erectile dysfunction. Testosterone is also considered for women with estrogen-sensitive breast cancer and other conditions, though virilizing side effects limit its use.



University of Chicago surgeon Charles Huggins discovers that blocking testosterone production in the testes slows progression and relieves symptoms of advanced prostate cancer, stirring concerns that the hormone may trigger the disease.



Doctors debate the value of testosterone treatment and the existence of a male version of menopause. The Male Hormone, by biologist Paul de Kruif, promotes testosterone for aging males, claiming the hormone increases libido, builds muscle and sharpens wits. But skeptics call the “male climacteric” a rare condition and caution against overuse of testosterone.




Swiss surgeon Paul Niehans’s Introduction to Cellular Therapy is published, promoting the “revitalizing” effects of testicle cell injections. Patients treated with the therapy include Pope Pius XII, financier Bernard Baruch and shipping magnate Aristotle Onassis.



The first testosterone transdermal patch becomes available, paving the way for wider use of TRT. The floodgates open in 2000 when the FDA approves the first testosterone gel; testosterone patches and gels now account for 70% of all TRT prescriptions in the United States.




Annual sales of testosterone therapy products top $1.64 billion in the United States.