Triptorelin
Triptorelin (D-Trp6-GnRH) · Trelstar · Decapeptyl · Triptodur · D-Trp6-LHRH · Trip
Long-acting GnRH agonist taken as one microdose to fire off a large LH and FSH surge.
Typical dose
100 mcg
Single one-off dose
Range
50–100
mcg
Half-life
2.8 h
see Dosing
Evidence
Human trials
Subcutaneous · Intramuscular
What it is
Triptorelin is a GnRH agonist: the native decapeptide with the glycine at position 6 swapped for D-tryptophan, which makes it far more resistant to enzymatic breakdown and much more potent at the receptor. Licensed depot forms are used for prostate cancer, endometriosis and central precocious puberty, where the goal is the opposite of what this community wants, namely shutting the axis down completely.
The bodybuilding use exploits the first half of that pharmacology. Any GnRH agonist causes a large flare of LH and FSH release before downregulation sets in, and a single small dose produces the flare without the shutdown that follows sustained exposure. A one-off 100 mcg subcutaneous injection is the standard community protocol, taken at the end of a cycle once exogenous androgens have cleared, in the hope of jump-starting a stalled axis.
Be clear about the evidence: the flare itself is thoroughly documented, including in diagnostic stimulation testing where a single 100 mcg subcutaneous dose reliably produces a strong LH response. Whether that one surge translates into durable HPTA recovery in an androgen-suppressed lifter is entirely anecdotal, and reports are mixed.
How it works
Triptorelin binds the pituitary GnRH receptor far more tightly than native GnRH and resists the peptidases that clear gonadorelin in minutes, so a single dose keeps signalling for hours. That produces a sustained release of stored LH and FSH, with testosterone typically climbing for several days afterwards. The sequence is pyroglutamyl at the N-terminus, D-Trp at position 6 and a C-terminal glycinamide, so the plain single-letter string above cannot show the D-amino acid substitution that defines the molecule.
Continue that receptor occupancy and the pituitary responds by internalising GnRH receptors and uncoupling the signal, which is why depot triptorelin produces castrate testosterone within 2 to 4 weeks. The entire community protocol rests on staying on the early, stimulatory side of that curve: one small dose, then nothing.
Dosing
The stimulatory flare is a one-shot effect: repeated or larger doses hold the GnRH receptor occupied, downregulate the pituitary and produce the castrate testosterone levels that depot triptorelin is prescribed to achieve. Community consensus is one 100 mcg dose per cycle and no more, and the administrationsPerWeek value of 1 here reflects that single shot rather than a weekly schedule.
Reconstitution calculator
Pre-loaded with Triptorelin’s vial size, water volume and typical dose. Change anything.
Typical: 100 mcg · range 50–100
Draw to
100 u
1 mL · 100 mcg
Concentration
0.1 mg/mL
1 mcg per unit
Doses per vial
1
Vial lasts
7 days
CheckThe draw fills more than 90% of the barrel. Workable, but there is no room for an air bubble or a correction.
Once mixed
Refrigerate at 2-8 °C and use within about 4 weeks in bacteriostatic water. Since almost everyone uses a single dose, the practical answer is to draw what you need and discard the rest rather than storing a vial you have no plan for.
A 100 mcg vial in 1 mL of bacteriostatic water gives 100 mcg/mL, so the standard dose is the whole millilitre, matching the licensed 0.1 mg/1 mL immediate-release ampoule. If you have a 2 mg research vial instead, 2 mL of water gives 1,000 mcg/mL and 100 mcg is 0.1 mL, or 10 units on a U-100 syringe: measure that carefully, because a slip of a few units here is a meaningful overdose.
Storage
Before mixing
Refrigerate at 2-8 °C protected from light; the powder is stable for years and survives room-temperature shipping.
After mixing
Refrigerate at 2-8 °C and use within about 4 weeks in bacteriostatic water. Since almost everyone uses a single dose, the practical answer is to draw what you need and discard the rest rather than storing a vial you have no plan for.
Reported benefits
- ▪One injection instead of weeks of daily hCG or gonadorelin shots
- ▪Raises both LH and FSH, unlike hCG which only replaces LH signalling
- ▪Testosterone typically climbs for several days after the dose
- ▪Less estradiol rise than hCG, though the flare still lifts testosterone for several days and estradiol follows it
- ▪Cheap: a single 100 mcg dose costs very little
- ▪Works upstream, so a good response also confirms the pituitary is functional
Side effects
- ▪Overdosing or repeating the dose causes profound suppression, the exact opposite of the intent
- ▪Hot flushes, sweating and fatigue in the days after injection
- ▪Headache and mood swings as gonadotropins and testosterone move sharply
- ▪Injection-site reactions and occasional transient testicular ache
- ▪Response is unpredictable: some men see a strong LH rise and others almost nothing
- ▪Depot and repeated exposure reduce bone mineral density, which is why oncology use is time-limited
- ▪Pituitary apoplexy: rare but reported after a first GnRH-agonist dose, usually in men with an undiagnosed pituitary adenoma — sudden severe headache, vomiting, visual disturbance or collapse is a medical emergency
- ▪Convulsions, a labelled GnRH-analogue class effect that has occurred with and without a prior seizure history
Do not use if
- ▪Known hypersensitivity to GnRH or its analogues
- ▪Any intention to use it more than once in a short window, given the downregulation risk
- ▪Existing pituitary disease or a known non-functional pituitary
- ▪Use while still running suppressive androgens, where it accomplishes nothing
Evidence level — Human trials
Controlled human clinical data exists.
Prescription-only and approved worldwide as a depot injection for prostate cancer, endometriosis and central precocious puberty, with immediate-release ampoules and research-chemical vials circulating outside those channels.
Triptorelin FAQ
Does a single 100 mcg shot really restart the axis?+
The LH and FSH surge is real and well documented, including in diagnostic testing where a single subcutaneous 100 mcg dose produces a robust LH response. Whether that surge produces lasting recovery in a suppressed lifter has never been studied, and forum reports are genuinely split. Treat it as a plausible one-shot attempt, not a guaranteed fix.
What happens if I take more than 100 mcg, or dose it twice?+
You move from flare to downregulation. Sustained GnRH receptor occupancy internalises the receptor and switches gonadotropin output off, which is precisely how depot triptorelin drives prostate cancer patients to castrate testosterone in 2 to 4 weeks. The mistake can cost months of recovery.
When in PCT should it go?+
At the point where all exogenous androgens have cleared, so the pituitary and testes can actually respond. With long esters that is several weeks after the final injection. Most people who use it take the shot at the start of their SERM phase or shortly before it.
Triptorelin or hCG?+
They are alternatives, not partners. hCG works at the testis and holds testicular function steadily while you are suppressed, with a lot of human evidence behind it and a known estradiol cost. Triptorelin is a single upstream attempt to restart a stalled axis after the fact, with far more downside if you get the dose wrong.
References
- 1.Pharmacokinetics of triptorelin after intravenous bolus administration in healthy males and in males with renal or hepatic insufficiency — British Journal of Clinical Pharmacology (1997) PMID 9354307
- 2.Pharmacokinetics and pharmacodynamics of triptorelin — Annales d'Urologie (2005) PMID 16302716
- 3.Effectiveness of the triptorelin stimulation test compared with the classic gonadotropin-releasing hormone stimulation test in diagnosing central precocious puberty in girls — Annals of Pediatric Endocrinology & Metabolism (2024) PMID 38712492
More hpta & fertility
Gonadorelin
Native GnRH decapeptide, now the usual compounded stand-in for hCG on TRT.
200 mcg · 1-2x daily
hCG
LH-mimic that keeps the testes producing while exogenous androgens shut the axis down.
500 IU · Every other day, or 2-3x per week
hMG
Urine-derived FSH plus LH activity, added to hCG when sperm counts will not recover.
75 IU · 3x per week
Kisspeptin-10
Upstream GnRH trigger — the switch that makes the hypothalamus fire and the pituitary release LH.
50 mcg · 3x weekly on non-consecutive days