What puberty blockers are – and why many detransitioners say the changes are not reversible

Puberty blockers (medicines such as leuprolide or triptorelin) shut down the brain signal that tells the ovaries or testes to make oestrogen or testosterone. Doctors sometimes call this a “pause”, but people who used them and later stopped say the body does not simply start where it left off. Below are the main points they raise, in their own words.

1. The body’s one-time window closes for good
"Puberty isn’t a switch that we can control… Once you go past the window, that’s it. It’s over." – ReaperManX15 source [citation:52f89ce8]
Detransitioners explain that bone growth, genital enlargement, brain organisation and the whole chain of physical changes happen in a set order. If that sequence is missed, later hormones cannot re-create it.

2. After only a few months the risk climbs sharply
"Up to three months and you should be fine… After that it gets dicey. The longer you take them the less likely it is." – TheDorkyDane source [citation:39f0d291]
Users who were on blockers for years report that even stopping the drug could not give back the growth spurts, bone mass or sexual development that normally occur in early puberty.

3. Bones, brain and fertility are often permanently affected
"Everything from IQ (lowering it) to bone density… That stuff is so dangerous it’s only prescribed to the very worst sex offenders to chemically castrate them." – Ok_Bullfrog_8491 source [citation:a87fcba8]
Several people describe lifelong brittle bones, unexplained fractures and, for some, the inability ever to produce viable sperm or eggs.

4. Sexual organs and function may never reach adult size or sensation
"He is nearly 30… his ‘junk’ is prepubescent boy-sized. He is sterile for life. And he will never experience an orgasm." – taiwanjohn source [citation:662ba522]
Because external testosterone or oestrogen cannot restart the first, finely-timed growth phase, the penis, clitoris, vaginal canal or uterus often stay under-developed even after years of replacement hormones.

5. The body keeps ageing even while puberty is “paused”
"Puberty blockers don’t literally block puberty, they just block sexual maturation… The rest of puberty (physical growth, brain maturation, bone growth) still happens." – Your_socks source [citation:140cbc68]
This means the biological clock moves on: growth plates close, neurons wire, and organs mature on schedule, but without the sex-hormone guidance that gives them their adult form and function.

Take-away
People who used blockers and later detransitioned want others to know that “reversible” is, in their experience, a medical half-truth. Once the natural puberty window is lost, the body cannot fully re-enter that programme, and late hormones do not replace the intricate, time-locked cascade of development that creates adult bone strength, fertility, genital size or sexual feeling. If you are questioning gender or struggling with dysphoria, they encourage exploring non-medical support—therapy, community, creative outlets, bodily acceptance—rather than assuming a chemical “pause” can be undone later.