Puberty blockers were originally developed to treat advanced prostate cancer in adult men. The first drug in this class, leuprolide (brand name Lupron), received FDA approval in 1985 specifically for that purpose. Within a few years, doctors recognized the same medications could treat a range of other hormone-driven conditions, and their use expanded to include children, women, and eventually adolescents with gender dysphoria.
How These Drugs Were Discovered
The story starts in 1971, when researchers first identified the structure of gonadotropin-releasing hormone (GnRH), a small signaling molecule produced in the brain that controls the release of sex hormones. Scientists quickly realized that if they could manipulate this hormone, they could control reproduction and hormone-dependent diseases. Early work focused on making synthetic versions of GnRH that lasted longer in the body than the natural form, which breaks down in minutes. By extending the molecule’s lifespan through small chemical tweaks, researchers created what are now called GnRH agonists.
These synthetic versions work through a paradox. A short burst of GnRH tells the pituitary gland to release hormones that drive testosterone or estrogen production. But when the pituitary is exposed to a constant, unrelenting supply of GnRH, it essentially shuts down. The gland’s receptors become overwhelmed and stop responding, cutting off the hormonal signals that drive puberty, tumor growth, or other hormone-dependent processes. Within weeks of continuous treatment, sex hormone levels drop to very low levels.
First Use: Advanced Prostate Cancer
Prostate cancer cells typically need testosterone to grow. By suppressing testosterone production, GnRH agonists could slow or shrink tumors in men with advanced disease. Lupron’s 1985 FDA approval was specifically for “palliative treatment of advanced prostate cancer,” meaning it was intended to manage symptoms and slow progression rather than cure the disease. A longer-acting depot injection followed in 1989, allowing patients to receive one shot per month instead of daily injections. This adult oncology application was the very first clinical use of what we now casually call puberty blockers.
Expansion to Women’s Health
Because GnRH agonists suppress estrogen as effectively as they suppress testosterone, doctors soon began using them for gynecological conditions. In endometriosis, tissue similar to the uterine lining grows outside the uterus and responds to estrogen, causing pain and inflammation. Continuous GnRH agonist treatment drops estrogen to postmenopausal levels, depriving those growths of the hormones that sustain them. Several studies showed that endometriosis lesions shrank or disappeared during treatment.
Uterine fibroids, benign muscle tumors in the uterus, also depend on estrogen. GnRH agonists can shrink fibroids before surgical removal, making the procedure easier and reducing blood loss. The shrinkage reverses after the medication stops, so these drugs are used as a bridge to surgery rather than a long-term fix. GnRH agonists also found a role in fertility treatment, where they help doctors precisely control the timing of ovulation during in vitro fertilization cycles.
Treating Children With Early Puberty
The pediatric application that most people associate with “puberty blockers” came in the early 1980s, when several GnRH agonist formulations were developed for children with central precocious puberty (CPP). This is a condition where the brain triggers puberty far too early, sometimes as young as age 2 or 3. In girls, CPP is typically diagnosed when puberty begins before age 8; in boys, before age 9.
Early puberty creates real problems. Children may experience rapid bone maturation that ultimately stunts their adult height, and the emotional and social burden of developing years ahead of peers can be significant. GnRH agonists pause this process by suppressing the same hormonal cascade they block in adults. Research shows the greatest height benefit comes when treatment starts in girls aged 6 or younger. Girls treated between 6 and 8 see variable results, and treatment after age 8 generally doesn’t improve adult height. Today, the FDA-approved drug Fensolvi (leuprolide acetate) is specifically indicated for children aged 2 and older with CPP.
Adaptation for Gender Dysphoria
The use of puberty blockers for adolescents with gender dysphoria began in the Netherlands. Dutch pediatric endocrinologist Henriette Delemarre-van de Waal treated the first patient in 1987, a 13-year-old who had experienced severe, persistent gender dysphoria since age 5 and had written a suicide note at 12 after extensive psychotherapy failed to help. That patient remained on blockers until age 18.
This individual case eventually led to a formalized approach. By 1997, Delemarre-van de Waal and psychologist Peggy Cohen-Kettenis had established what became known as the “Dutch Protocol.” Under this framework, carefully selected adolescents with early-onset gender dysphoria that worsened at puberty could receive blockers starting around age 12, cross-sex hormones at 16, and surgery at 18. This protocol became the model that clinics worldwide adopted and adapted over the following decades, though eligibility criteria and age thresholds have varied considerably across countries and time periods.
Effects on Bone Health
One consistent concern across all uses of GnRH agonists is their effect on bones. Sex hormones play a central role in building bone density, and adolescence is the critical window when the body accumulates most of its lifetime bone mass. Suppressing those hormones interferes with that process. In adult women, significant bone density losses have been documented after just 3 to 6 months of treatment, and some research suggests bone density may not fully return to baseline after stopping. In children treated for precocious puberty, the concern is similar: any delay in bone mineral accrual during key growth years could increase fracture risk later in life. For adult women with endometriosis, doctors sometimes prescribe small doses of supplemental hormones alongside the blocker (called “add-back therapy”) to protect bones while still treating the underlying condition.
What Happens When Treatment Stops
The hormonal suppression caused by GnRH agonists is generally reversible. When treatment stops, the pituitary gland resumes its normal signaling, and sex hormone production restarts. In children treated for precocious puberty, puberty picks up where it left off. A 2024 study presented at the American Physiological Society’s annual meeting examined this question in female rats given puberty blockers before puberty. The treated animals showed significant delays in reproductive organ development while on the medication, including thinner uterine lining and disrupted egg follicle development. But four weeks after stopping treatment, their reproductive organs had returned to normal. Pregnancy rates were comparable to untreated animals, though the treated rats became pregnant later, likely reflecting the time their reproductive systems needed to catch up.
The researchers noted their findings were consistent with previous studies showing that short-term GnRH agonist use does not permanently damage the ovaries or uterus. That said, the question of whether longer treatment durations or use during different developmental windows might carry different risks remains an active area of clinical attention, particularly as the drugs are used in contexts and for durations that differ from their original applications in prostate cancer and precocious puberty.