Peptide & Experimental
Trestolone (MENT)
Synthetic androgen (nandrolone derivative), clinically tested as a male contraceptive and as hormone replacement, never approved · MENT, 7α-methyl-19-nortestosterone, 7alpha-methyl-19-nortestosterone, Trestolon, trestolone acetate, MENT acetate
Trestolone, called MENT in research, is a synthetic androgen and a close relative of nandrolone. The Population Council developed it as an implant for male contraception and as hormone replacement that spares the prostate. The studies on it are small but controlled – it was never approved.
In short
In studies with around 140 men in total, MENT reliably suppressed the hormonal axis and thus sperm production: in the highest implant group, 8 of 12 men became sperm-free. In men with hormone deficiency, it maintained libido, erections and mood similarly to testosterone, and it spared the prostate. Against this stand a drop in bone density, a rise in hematocrit, a fall in HDL cholesterol and studies that lasted 12 months at most; the results of the last registered study have not been published. On the muscle effect, which is what matters outside research, there is not a single human study. In sport, trestolone is prohibited at all times.
What it is and how it works
Trestolone is 7α-methyl-19-nortestosterone, that is, nandrolone with an additional methyl group; nandrolone has its own entry: nandrolone decanoate. In the studies it was mostly given as the acetate in implants under the skin of the upper arm, which release the active substance evenly. For an overview of the substance class, see Anabolic steroids (anabolics, AAS).
It binds to the androgen receptor and is more potent than testosterone. Unlike testosterone, it is not converted by 5α-reductase and therefore stimulates the prostate less; it can, however, be converted to estrogen (Anderson 2003). Via feedback it suppresses LH and FSH and thus the body’s own testosterone and sperm production. In 24 healthy men in the highest dose group, testosterone fell by 74 %, LH by 70 % and FSH by 57 % (Suvisaari 1997). Precisely this suppression is the approach for contraception.
What is well supported
For a substance without approval, the data are unusually clean. Several controlled studies show in humans that MENT suppresses the hormonal axis in a dose-dependent manner and suppresses sperm production, in some cases down to zero. It is also established that in men with hormone deficiency it maintains sexual function and mood similarly to testosterone while sparing the prostate. All of this concerns contraception and hormone replacement – not muscle building.
What the studies show
Implants for contraception in 35 men
Healthy men at three centers were randomly assigned one, two or four MENT implants, for 6 to 12 months depending on the center. In the one-implant group, no one’s sperm count fell below 3 million per ml; in the two-implant group it did in 4 of 11, 2 of them sperm-free; in the four-implant group, 8 of 12 became sperm-free and 2 did not respond. Red blood cells, hematocrit and hemoglobin rose, SHBG fell; the changes reversed (von Eckardstein 2003).
MENT versus testosterone, each with a progestin
29 healthy men were randomly assigned two etonogestrel implants together with MENT or with testosterone. After 12 weeks, the sperm count was below 1 million per ml in 8 of 10 men in the MENT group, similar to testosterone. After that, release from the MENT implants declined, suppression did not last, and 6 men noticed a loss of libido. In both groups hemoglobin rose and HDL cholesterol fell; on MENT, PSA decreased (Walton 2007).
Hormone replacement: sexual function and mood
20 men with hormone deficiency in Edinburgh and Hong Kong received MENT implants and testosterone enanthate for 6 weeks each in a crossover design. Both increased sexual interest, activity and spontaneous erections; differences between the treatments were small, and no toxic effects occurred (Anderson 1999).
Sparing the prostate, losing bone
16 men with hormone deficiency received one or two implants over 24 weeks. Hemoglobin and hematocrit remained stable, PSA fell in both groups, prostate volume in part; with two implants, sexual behavior and erections were maintained, with one they declined. The bone density of the lumbar spine decreased in both groups – in the authors’ assessment an indication that hormone replacement needs sufficient estrogenic action (Anderson 2003).
Blood pressure study without published results
From 2008, the Population Council tested the effect of a MENT gel on blood pressure in a randomized, double-blind phase 1 study with 68 men. The study was completed in March 2014; no results have been posted in the registry (NCT00812630).
Where the data stop
All studies are small, with 16 to 35 participants per study, and lasted 12 months at most. The results of the most recent registered study have not been posted in the registry, and no further study has been registered on ClinicalTrials.gov since.
What trestolone is used for outside research has not been studied in humans at all: muscle building and performance. The often-cited anabolic effect ten times stronger than testosterone comes from investigations in the 1960s in the context of cancer research (Piper 2026). Data on the heart and blood vessels and on longer use are also lacking. What is traded on the internet is not the study preparation.
Status, approval and legal
Trestolone is not approved as a medicine in any country; development as a contraceptive implant did not progress beyond small clinical studies. In Germany no product is listed (Gelbe Liste, as of 10/2026), and an unapproved finished medicinal product may not be placed on the market (§ 21 German Medicines Act). Trestolone is on the WADA Prohibited List 2026 under S1.1 and is prohibited at all times; consequently, manufacture, trade, supply and prescription for doping purposes are prohibited under § 2(1) of the German Anti-Doping Act. It is not named specifically in the annex to the Anti-Doping Act, which governs acquisition and possession of non-small quantities; the annex lists in general terms “other substances related to anabolic-androgenic steroids”.
Safety
In the studies, red blood cells, hematocrit and hemoglobin rose, SHBG and HDL cholesterol fell, blood lipids changed temporarily and liver values slightly (von Eckardstein 2003, Walton 2007). The bone density of the lumbar spine decreased over 24 weeks (Anderson 2003). As soon as the level was too low, libido and erections declined. The body’s own testosterone and sperm production is suppressed; in the contraception studies this was intended. For the substance class as a whole, heart damage and a hormonal axis that does not always recover are documented; see Anabolic steroids (anabolics, AAS). Before any step, a conversation with a physician belongs here – not as a formality, but because of consequences that can be lasting.
BK-Score Thin human evidence
| Human evidence | 4 | |
|---|---|---|
| Mechanism | 7 | |
| Safety data | 3 | |
| Hype gap | 3 | |
| Track record of use | 3 |
Evidence 4, because small controlled studies with around 140 men in total show that MENT suppresses sperm production – 8 of 12 men sperm-free in the highest implant group (von Eckardstein 2003) – and maintains libido and erections in hormone deficiency similarly to testosterone (Anderson 1999, 20 men), while there is not a single human study on the muscle effect, which is what matters outside research. Mechanism 7, because the hormone suppression has been measured in humans (testosterone −74 %, LH −70 %, FSH −57 %, Suvisaari 1997) and the sparing of the prostate due to the absence of conversion via 5α-reductase was shown in humans for the first time (Anderson 2003). Safety 3, because the data come from studies of at most 12 months with 16 to 35 participants each – with a rise in hematocrit and a fall in HDL and bone density – and the results of the blood pressure study with 68 men have not been published (NCT00812630). Hype 3, because an anabolic effect ten times stronger than testosterone is passed on from investigations in the 1960s that was never tested in humans. Use 3, because the substance was never approved and outside the studies is used only without medical supervision. Direction open: human data for the advertised effect are lacking.
The score rates the state of knowledge, not the substance. “Safety data 9” means well studied – not harmless.
Subjective assessment by Biohacking Kompakt based on published scoring rules – not a scientific rating and not a medical recommendation. Rules and all ratings (German)
Frequently asked questions about trestolone
What is MENT?
MENT is the research name for trestolone, 7α-methyl-19-nortestosterone. The Population Council developed it as an implant for male contraception and as hormone replacement.
Does trestolone work as a contraceptive for men?
In small studies it suppressed sperm production; in the highest implant group, 8 of 12 men became sperm-free. In another study the effect did not last because the implants released less active substance over time. There is no approved product.
Does trestolone build muscle?
There is not a single study on this in humans. The often-cited anabolic effect ten times stronger than testosterone comes from investigations in the 1960s and was never tested in humans.
What does trestolone do to bones and blood values?
In the studies, hematocrit and hemoglobin rose, HDL cholesterol fell, and in men with hormone deficiency the bone density of the lumbar spine decreased over 24 weeks.
Is trestolone legal in Germany?
There is no approved medicine, so placing it on the market is not permitted. For doping purposes, manufacture, trade and supply are prohibited under the German Anti-Doping Act, and in sport it is on the Prohibited List at all times.
Related
- Related topicOxymetholone (Anadrol)
- Related topicS-23
- Related topicStanozolol (Winstrol)
- Related topicDHB (1-testosterone, dihydroboldenone)
- Related topicDrostanolone (Masteron)
- Related topicAnabolic steroids (anabolics, AAS)
Sources
- von Eckardstein S et al., J Clin Endocrinol Metab 2003 – MENT implants as long-term contraception for men, 35 participants
- Walton MJ et al., J Androl 2007 – MENT versus testosterone, each with an etonogestrel implant, 29 healthy men
- Anderson RA et al., J Clin Endocrinol Metab 2003 – tissue selectivity of MENT in 16 men with hormone deficiency
- Anderson RA et al., J Clin Endocrinol Metab 1999 – MENT maintains sexual behavior and mood in men with hormone deficiency
- Suvisaari J et al., Hum Reprod 1997 – pharmacokinetics and hormone suppression after injection in healthy men
- ClinicalTrials.gov NCT00812630 – Population Council, MENT and blood pressure, 68 men, completed 2014, no published results
- Piper T et al., Drug Test Anal 2026 – metabolism of trestolone in humans, detection in doping control
- German Medicines Act (AMG), § 21 marketing authorization requirement
- German Anti-Doping Act (AntiDopG), § 2 and annex
- Prohibited List in sport 2026: S1.1, trestolone (WADA Prohibited List)
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Information only, not medical advice and not a usage or dosage recommendation. Prescription-only and unapproved substances belong in the hands of a physician. Last updated: 2026-10-05.