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Muscle & performance

Trenbolone Acetate

The strongest classic anabolic - extreme effect, extreme side effects, short ester.

2 min read 9 sources

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Glass vial with golden oil and a black TPD label on a white podium, next to it a large blue 3D steroid molecule in a bright lab
Preclinical · not approved

Summary

At a glance

Sources checked on 26 Oct 2026

Binding to the androgen receptor
~3 x

About three times the affinity of testosterone, review of animal data3

Less prostate than with testosterone
64 %

Rats without testes, trenbolone versus high-dose testosterone enanthate, 5 weeks6

Femoral neck strength
+28 %

Rats without testes, compared with untreated animals without testes6

In humans on the registry
0 trials

no phase 1 to 3, as of 26 Oct 20268

With a side effect
100 of 100

Cohort of anabolic steroid users in general, not only trenbolone, four with a serious event7

  • Trenbolone Acetate is a 19-nor anabolic with a short acetate ester. Trenbolone binds the androgen receptor about three times as strongly as testosterone and is not converted to estradiol.3
  • In a receptor assay trenbolone bound the androgen receptor about as strongly as DHT and the bovine progesterone receptor slightly more strongly than progesterone. Its breakdown products bound only weakly.4
  • In rats without testes trenbolone increased muscle mass, protected bone density and enlarged the prostate less than testosterone.56
  • The data come almost only from animal studies. Trenbolone has never been approved for humans and there is no trial on the registry. In livestock farming it serves as a growth promoter.384
  • In a cohort of 100 anabolic steroid users, not only on trenbolone, every one had at least one side effect and four had a serious event. Everything here is the state of research, not a recommendation.7
Profile

Updated June 2026

How long does it stay in the body?

Share left after one dose, calculated with a half-life of ~24 hours

Half-life ~24 hours
After 48 hours: 25 %
Hour 24 · 50 %Hour 48 · 25 %Hour 72 · 12.5 %Hour 120 · 3.1 %

Simplified model without an absorption phase, half-life from the TPD lexicon.

Class
19-nor anabolic

short acetate ester

Use
Intramuscular

every other day

Half-life
about 1 day
WADA
banned

anabolic

Sizes
2 sizes

100mg/ml, 200mg/ml

Contents 14 sections
  1. At a glance
  2. What is Trenbolone Acetate?
  3. How it works
  4. How to use it
  5. Dosing
  6. What the research shows
  7. Research status
  8. Side effects
  9. Storage
  10. PCT / after coming off
  11. Related compounds
  12. FAQ
  13. Glossary
  14. Sources

What is Trenbolone Acetate?

Trenbolone Acetate (Tren A) is a 19-nor anabolic with a short acetate ester. It binds the androgen receptor extremely strongly - much more than testosterone - and does not aromatize to estrogen. Originally from veterinary medicine (Finaplix, cattle), it is considered one of the most potent anabolics there is.

This information is for research and educational purposes only. No medical advice.

Comparison

Trenbolone esters compared

The same compound at the same receptors with esters of different length, as stated in the TPD lexicon. Tap a card to open its entry.

Short ester Trenbolone Acetate ARPR
Long ester Trenbolone Enanthate ARPR Very long ester Tren Hex (Parabolan) ARPR

41

How it works

Trenbolone activates the androgen receptor with very high affinity and massively raises protein synthesis, nitrogen retention and nutrient efficiency. It does not aromatize but has progesterone receptor activity (progestin effect) - so despite the lack of aromatization it can cause side effects via the prolactin pathway.

Where it acts

Two receptors, several organs

Tap a point or a card. Grey = effect seen in trials.

  1. Skeletal muscle

    Test muscle in rats 35 to 40 percent heavier than in untreated animals5

    Observed in trials
  2. Bone

    Bone density preserved after removal of the testes, femoral neck stronger6

    Observed in trials
  3. Prostate

    Unchanged at a low dose, clearly less growth than with testosterone6

    Observed in trials
  4. Visceral fat

    Gain in visceral fat after removal of the testes partly prevented5

    Observed in trials
  5. Blood

    Haemoglobin rose in older rats similarly to testosterone6

    Observed in trials

Known targets4

Compound CHEMBL197309: two described targets, type of action on each card.

Androgen receptor
Gene
AR
UniProt
P10275
ChEMBL
CHEMBL1871
Action
Binds about as strongly as DHT (human receptor in an assay)
Progesterone receptor
Gene
PGR
UniProt
P06401
ChEMBL
CHEMBL208
Action
Binds slightly more strongly than progesterone (bovine receptor in an assay)
Blue 3D molecule sits snugly in a glowing blue hollow on bright fibres, next to empty transparent rings and hollows
Trenbolone binds very tightly to the androgen receptor. Symbolic image.

How to use it

Dosing. Loading the dosing information …
Glass vial with golden oil and a black TPD label, a disposable syringe in front on a white surface
Short ester: usually given into the muscle every other day. Symbolic image.

Dosing

Dosing

Dosing, titration and syringe

Loading the dosing information …

  • Getting started and stepping up, drawn as a staircase
  • Units on the U-100 syringe for every step
  • How long one vial lasts

What the research shows

Human studies on trenbolone itself are scarce (it is primarily veterinary). The pharmacology of anabolic steroids is well documented (Kicman, Br J Pharmacol 2008; Hartgens & Kuipers, Sports Med 2004) - trenbolone's high androgen receptor affinity and lack of aromatization are described there.

Study results

What the trials measured

Interactive: switch tabs, tap points, show or hide arms. Arms are named relative to each other, no dosing advice.

Prostate mass compared with untreated animals56

Change in percent in rats, trenbolone given as enanthate

Young rats, 29 days5
Testosterone enanthate, high dose (comparison) +84%
Trenbolone, highest level +68%
Older rats without testes, 5 weeks6 difference not significant
Trenbolone -20%

In the study with young rats the lowest trenbolone levels kept prostate and haemoglobin at the level of untreated animals. In the study with older rats testosterone nearly doubled the prostate, with trenbolone it was 64 percent lower.

Femoral neck strength6

Change in percent versus untreated rats without testes, 5 weeks

Femoral neck6
Trenbolone +28%

Testosterone enanthate did not change strength. Both completely prevented the loss of bone density at the femur after removal of the testes and both increased the test muscle (levator ani) to a similar degree.

Translucent kidney model on a metal shelf between stacked petri dishes in a lab fridge
The data come almost only from animal and lab studies. Symbolic image.

Research status

Where the research stands

Where the compound stands on the way from lab research to approval. As of 26 Oct 2026. 8

  1. Preclinical Receptor assays and animal models (rats)
  2. Phase 1 no registered trial
  3. Phase 2 no registered trial
  4. Phase 3 no registered trial
  5. Approval not yet
Never approved for humans, no registered human trial. In livestock farming Trenbolone Acetate is used as a growth promoter.8

So far there is no registered trial in humans. 8

Side effects

  • Prolactin/progestin: via progesterone activity - libido issues, possible gyno despite no aromatization. Cabergoline is the usual countermeasure.
  • Night sweats, sleep issues, aggression: classic tren symptoms.
  • Tren cough: brief coughing fit right after injection.
  • Cardiovascular: unfavorable lipids, raised blood pressure.
  • HPTA suppression: strong - PCT topic.

Tolerability

Side effects in anabolic steroid users

Out of 100 anabolic steroid users, how many had the event. Observational study with all agents, not a study of trenbolone alone.

58 of 100 Anabolic steroid users (all agents)
Event Anabolic steroid users (all agents)
Lower libido after the cycle7 58%
Fluid retention7 56%
Agitation7 36%
Acne7 28%
Gynaecomastia7 19%

Every one of the 100 men had at least one side effect, four had a serious event (heart failure, pancreatitis, suicidal thoughts, flare of a bowel inflammation). One year after the start the observed effects were back at baseline.7

Storage

Store the oil solution at room temperature, protected from light - no fridge needed. Out of reach of children.

Four glass vials with golden oil on a white shelf, next to them a folded light blue cloth
Oil solution at room temperature and protected from light, no fridge needed. Symbolic image.
Level · Trenbolone Acetate

How the level builds up

One dose every other day: each dose adds to what is left of the previous one.

Lexicon: Intramuscular, every other day
Peak 1.33×Trough 0.33×
Day 4 · 3. dose
1.31× of the first dose
Plateau
from Day 4

98 % of the plateau after dose 3

Peak
1.33×

of the first dose

Trough
0.33×

before the next dose

Simplified model, values relative to the first dose, no dosing information. Dashed: the first dose alone, green: the plateau.

Related

Related compounds

Same receptors or blends with Trenbolone Acetate: all in the TPD lexicon.

Trenbolone Acetate
Trenbolone Enanthate Long ester, less frequent doses Tren Hex (Parabolan) Very long ester Methyltrenbolone (Metribolone) Methylated oral form TrenMix 200 Contains trenbolone acetate plus enanthate Test/Tren Short 150 Contains trenbolone acetate plus testosterone propionate Tren/Test/Mast Short 150 Contains trenbolone acetate plus testosterone and drostanolone RIPEX 225 Contains trenbolone acetate plus testosterone and masteron (short esters)

FAQ

Common questions about Trenbolone Acetate

Short answers, each backed by the sources below.

Is trenbolone approved for humans?

No. Trenbolone has never been approved for humans. There is not a single trial with it on ClinicalTrials.gov. In livestock farming Trenbolone Acetate serves as a growth promoter. The research rests almost only on animal studies. Everything here is the state of research, not a recommendation.843

How strongly does trenbolone bind the androgen receptor?

Very strongly. A review states about three times the affinity of testosterone. In an assay with the human androgen receptor trenbolone bound about as strongly as DHT. The two main breakdown products bound only weakly, at less than 5 percent of that.34

Why are there progestin effects despite no aromatization?

Trenbolone is not converted to estradiol. It does, however, also bind the progesterone receptor, in an assay with the bovine receptor even slightly more strongly than progesterone itself. This is how the entry explains the progestin and prolactin issues that can occur without estrogen.43

What do the animal studies show?

In rats without testes trenbolone (as enanthate) made the test muscle 35 to 40 percent heavier, protected bone density and slowed the gain in visceral fat. The prostate grew less than with testosterone: by 68 percent at the highest level, by 84 percent with testosterone. In older rats the femoral neck was 28 percent stronger.56

What is known about side effects in humans?

There are no controlled trials with trenbolone. In a cohort of 100 anabolic steroid users taking different agents every one had at least one side effect: most often fluid retention (56 percent) and agitation (36 percent) during the cycle and lower libido afterwards (58 percent). Four men had a serious event.72

Why acetate and not a long ester?

The ester only sets how fast trenbolone is released from the oil depot. Acetate is short, so levels rise and fall quickly. That requires frequent doses, but effects also fade faster after stopping than with enanthate or hexahydrobenzylcarbonate.1

Glossary

Terms explained briefly

Dotted words in the text open these explanations directly.

19-nor anabolic
Steroid without the methyl group at position 19 of testosterone. Trenbolone and nandrolone belong to this group.
5-alpha reductase
Enzyme that converts testosterone into the stronger DHT in tissues such as the prostate. Trenbolone is not amplified this way.
Androgen receptor
Protein inside the cell that testosterone and trenbolone bind to. Genes are then read, for example for muscle building.
Aromatization
Conversion of testosterone into estradiol by the enzyme aromatase. Trenbolone is not converted this way.
Ester
An attached acid chain. The shorter it is, the faster the compound is released from the oil depot.
Hormone axis (HPTA)
Hypothalamus, pituitary and testes together control the body's own testosterone production. Anabolics from outside suppress this axis.
Levator ani
Pelvic floor muscle of the rat that responds strongly to androgens and therefore serves as a test muscle.
Preclinical
Research before human trials: cell experiments, receptor assays and animal models.
Progesterone receptor
Receptor for the corpus luteum hormone progesterone. Substances that activate it are called progestins.
Prolactin
Pituitary hormone, among other things for milk production. Raised levels can impair libido and erection.
SARM
Selective androgen receptor modulator: a substance that acts more on muscle and bone than on the prostate.

Practice

PCT / after coming off

Anabolic substances suppress the body's own testosterone production in the research context. Anyone who comes off a cycle (rather than running it continuously) typically uses a post-cycle therapy (PCT) to restart the natural axis (HPTA).

The standard scheme in the research/literature context combines a SERM (tamoxifen and/or clomifene, alternatively enclomiphene) over roughly four weeks, optionally preceded by HCG to re-sensitise the testes before the SERM block. An aromatase inhibitor (anastrozole/exemestane) belongs more to on-cycle estrogen control than to the PCT itself.

19-nor note: nandrolone and trenbolone are progestagenic and can raise prolactin. The literature additionally discusses a prolactin-lowering agent (cabergoline) and a somewhat longer wash-out window here.

Tip: order the PCT items together with the cycle so they are already on hand when you come off.

This information serves research and educational purposes only. Not medical advice.

Tamoxifen (Nolvadex) SERM, core of PCT View Clomid (Clomifen) SERM, core of PCT View Enclomiphene (Androxal) SERM alternative View HCG testicular restart before PCT View Arimidex (Anastrozole) aromatase inhibitor, on-cycle View Aromasin (Exemestane) aromatase inhibitor, on-cycle View Cabergoline prolactin control for 19-nor View

Evidence

Sources

Show all 9 sourcesHide sources 7 Studies1 Trial registry1 Database checked 26 Oct 2026

Studies

  1. Pharmacology of anabolic steroids, review

    Kicman, British Journal of Pharmacology, 2008

    DOI 10.1038/bjp.2008.165 PMID 18500378
    Checked 26 Oct 2026 via doi.org, Crossref, PubMed
  2. Effects of anabolic steroids in athletes, review

    Hartgens and Kuipers, Sports Medicine, 2004

    DOI 10.2165/00007256-200434080-00003 PMID 15248788
    Checked 26 Oct 2026 via doi.org, Crossref, PubMed
  3. Trenbolone: tissue selectivity and potential applications, review

    Yarrow et al., Steroids, 2010

    DOI 10.1016/j.steroids.2010.01.019 PMID 20138077
    Checked 26 Oct 2026 via doi.org, Crossref, PubMed
  4. Binding to androgen and progesterone receptors in assays

    Bauer et al., APMIS, 2000

    DOI 10.1111/j.1600-0463.2000.tb00007.x PMID 11252818
    Checked 26 Oct 2026 via doi.org, Crossref, PubMed
  5. Muscle, bone, fat, haemoglobin and prostate in rats

    Yarrow et al., American Journal of Physiology: Endocrinology and Metabolism, 2011

    DOI 10.1152/ajpendo.00440.2010 PMID 21266670
    Checked 26 Oct 2026 via doi.org, Crossref, PubMed
  6. Bone density and prostate in older rats without testes

    McCoy et al., Bone, 2012

    DOI 10.1016/j.bone.2012.07.008 PMID 22842328
    Checked 26 Oct 2026 via doi.org, Crossref, PubMed
  7. HAARLEM: side effects in 100 anabolic steroid users over one year

    Smit et al., Scandinavian Journal of Medicine and Science in Sports, 2020

    DOI 10.1111/sms.13843 PMID 33038020
    Checked 26 Oct 2026 via doi.org, Crossref, PubMed

Trial registry

  1. Search for trenbolone on ClinicalTrials.gov

    ClinicalTrials.gov, U.S. National Library of Medicine

    Checked 26 Oct 2026 via ClinicalTrials.gov API v2

Database

  1. Trenbolone in ChEMBL

    ChEMBL, EMBL-EBI (CHEMBL197309, Acetat CHEMBL1698011)

    Checked 26 Oct 2026 via ChEMBL

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