This is one of the annoying things about life. Testosterone effectively already does this and is quite safe. It's just that society is not comfortable with men taking steroids for no particularly good reason.
Taking outside sources of testosterone permanently alters your body's ability to make testosterone naturally, to the extent that many people who previously took steroids find they have be on testosterone therapy for the rest of their lives.
I wouldn't call "creating a lifelong requirement to take artificial hormones in order to function at your previous baseline" qualifying as "no particularly good reason".
>Ever since that study, testosterone has undergone extensive clinical trials as a hormonal method of male contraception and many have found testosterone to be efficacious, reversible and safe with minimal short-term side effects
https://pmc.ncbi.nlm.nih.gov/articles/PMC6305868/
It's not super reliable but it's also easily testable if it's working or not.
Let's quote the short, succinct conclusion of the study you picked:
> Testosterone therapy is a contraceptive, albeit a poor one. Men of reproductive age with low testosterone should be counseled on the adverse effects of TRT on fertility. Obtaining a semen analysis and possible cryopreservation of sperm should be offered if TRT is prescribed to men interested in preserving fertility. Options such as clomiphene citrate and hCG along with a referral to a reproductive urologist should be considered to naturally increase testosterone levels in those men with low testosterone who want to avoid TRT.
Whether a contraceptive that is sufficiently irreversible that men using it are advised to freeze sperm if they ever want kids should be considered "reversible" is left as an exercise to the reader.
>If a patient currently desires fertility, TRT should be avoided or discontinued immediately. A semen analyses should be performed if the patient has discontinued TRT. Azoospermia or severe oligospermia may be seen in these patients, but most men should return to baseline semen analyses in 6 to 9 months after cessation of TRT [13,14,15]. A 2006 integrated analysis showed that 90% of patients were expected to return to baseline sperm concentration values 12 months after cessation of treatment and 100% after 24 months [50].
TRT is a very low dose of testosterone, used to supplement the body when it doesn't produce enough. It is reversible as you say, and has a negative effect on fertility but not enough to be reliably effective as a contraceptive at TRT dosages.
Testosterone as a contraceptive or steroid is a far higher dose. This is the one that has permanent effects.
"Testosterone as a contraceptive can suppress spermatogenesis and lead to azoospermia in 65% of normospermic men within 4 months of use"
Does this sound like a convenient and effective contraceptive? Where are you really coming from with this statement?
https://www.discovermagazine.com/health/the-myth-of-roid-rag...
What many people don’t realize (probably in large part because they see testosterone and estrogen as diametrically opposed things) is that testosterone levels impacts estrogen levels. Why? Because the body produces estrogen through the aromitization of testosterone. Increasing testosterone will increase estrogen.
A common struggle for those on TRT (both those at true replacement levels, as well as those taking supraphysiological doses) is elevated estrogen. I know that when my estrogen levels have gone too high, I become more neurotic than I usually am.
If you couple increased neuroticism with an elevated sense of dominance (especially at bodybuilding doses), and top that off with a general lack of poor management of one’s emotions (which I suspect is common amongst bodybuilders), what you likely get is a very volatile person. Not because of testosterone, but because of the elevated estrogen and their existing psychological issues.
As I wrote over in: https://news.ycombinator.com/item?id=43746406
I’m on TRT, without hCG. I went and had a vasectomy a year ago. Because I’m weird and infinitely curious, two or three days after the procedure, I took three samples per day, and looked at each under the microscope. What I saw put to shame just about any video I could find online of a “good” sperm sample. Straight laser beams, zipping from one side of the slide to the other. If you were to scale Micheal Phelps down to these swimmers, he’d stand no chance. And the concentration was ridiculous, too. And this all 2-5 day old (at least) sperm!
TRT is not a reliable form of birth control.