The Peptide Desk The Peptide Desk

This information is for research and educational purposes only. No medical recommendations. Products are not approved for human use. For health questions, consult a doctor.

Lexicon
Muscle & performance

Tren Hex (Parabolan)

The longest tren ester - the same potent trenbolone, just the most convenient to dose.

1 min read 14 sources

To the product To the sources
Glass vial with golden oil and a black TPD label on a white podium, next to it a long glossy blue 3D molecule with a ring at the end in a bright lab, symbolic image for Tren Hex
Preclinical · not approved

Summary

At a glance

Sources checked on 26 Oct 2026

Binding at the androgen receptor
~3 -fold

about three times as strong as testosterone, according to a review1

Muscle fibre cross-section (rats)
+94 %

compared with castrated rats without hormone after 29 days6

Concern about the heart
54.4 %

men using trenbolone in a survey, vs 31.2% with other anabolic steroids10

Trenbolone share of the molecule
~66 %

the rest is the hexahydrobenzylcarbonate ester, calculated from molar masses 270.4 and 410.5 g/mol14

Human trials in the registry
0 trials

no trial with trenbolone on ClinicalTrials.gov, as of 26 Oct 202612

  • Tren Hex is trenbolone with the long hexahydrobenzylcarbonate ester. The ester only controls the release from the oil depot, the active compound is the same trenbolone.114
  • In the lab trenbolone binds the androgen receptor about as strongly as DHT and also the progesterone receptor. It is not converted into stronger androgens.81
  • In rat studies muscle fibres and satellite cells rose clearly and bone density was preserved after castration. Low levels spared the prostate, high levels did not.654
  • In a survey of 1,146 men, users of trenbolone reported almost all concerns more often, above all concerns about heart and liver, irritability and aggression.10
  • The registry lists no human trial and there is no approval. Everything here is the state of research, not a recommendation.1213
Profile

Updated June 2026

How long does it stay in the body?

Share left after one dose, calculated with a half-life of ~8.5 days

Half-life ~8.5 days
After 17 days: 25 %
Day 3.5, next dose · 75 %Day 9 · 48 %Day 17 · 25 %Day 26 · 12 %Day 43 · 3 %

Simplified model without an absorption phase, half-life from the TPD lexicon. The lexicon gives 7 to 10 days, we calculate with the middle.

Class
19-nor anabolic

long hexahydrobenzylcarbonate ester

Use
Intramuscular

subQ possible, 2x per week

Half-life
about 7-10 days
WADA
banned

anabolic

Sizes
2 sizes

100mg/ml, 75mg/ml

Contents 14 sections
  1. At a glance
  2. What is Tren Hex?
  3. How it works
  4. Ester comparison
  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 Tren Hex?

Tren Hex (Trenbolone Hexahydrobenzylcarbonate, historically known as Parabolan) is the same trenbolone molecule as tren acetate and enanthate, just with the longest ester. That means the least frequent injections and very stable blood levels - at identical effect and identical side effect profile.

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

How it works

Identical to the other tren esters: very high androgen receptor affinity, no aromatization, but progesterone activity (prolactin topic). Once the ester is cleaved, the same trenbolone acts.

Where it acts

Where trenbolone acted in studies

Tap a point or a card. Grey = seen in studies, mostly in rats or by survey.

  1. Brain and mood

    Irritability, mood swings and aggression more common in surveys than with other anabolic steroids10

    Observed in trials
  2. Heart

    Concern about the heart in 54.4% of men with trenbolone, 31.2% without (survey)10

    Observed in trials
  3. Blood lipids

    HDL cholesterol -57%, LDL cholesterol -78%, triglycerides -62% (rats)7

    Observed in trials
  4. Skeletal muscle

    Muscle fibre cross-section +94%, satellite cells +178% after castration (rats)6

    Observed in trials
  5. Bone

    Bone density fully preserved after castration, femoral neck 28% stronger (rats)5

    Observed in trials
  6. Fat tissue

    Fat mass -37% in 6 weeks, control animals +34% (rats)7

    Observed in trials
  7. Hormone axis and prostate

    Own sex hormones suppressed, prostate benignly enlarged (rats)7

    Observed in trials

Known targets8

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, lab)
Progesterone receptor
Gene
PGR
UniProt
P06401
ChEMBL
CHEMBL208
Action
Binds slightly more strongly than progesterone (bovine receptor, lab)
A glass droplet full of blue 3D molecules releases single molecules onto a glossy surface with small hollows
The long ester releases trenbolone slowly from the depot. Symbolic image.

Ester comparison

  • Acetate: short, every other day, fastest to control.
  • Enanthate: medium-long, 2x per week.
  • Hexa (Parabolan): longest, 2x per week is plenty, very stable levels.

Comparison

One compound, three esters

The same trenbolone 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
Longest ester Tren Hex (Parabolan) ARPR

The ester only changes how fast trenbolone leaves the depot. There is no human study comparing the esters. 8

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

As with all tren esters, the AAS pharmacology applies (Kicman 2008, Hartgens & Kuipers 2004). Compound-specific human studies are scarce since trenbolone is primarily veterinary.

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.

Muscle after castration (rats)6

Increase compared with castrated rats without hormone after 29 days, pelvic muscle

Muscle fibre cross-section6
Testosterone enanthate (comparison) +102%
Trenbolone +94%
Satellite cells6 Muscle stem cells
Testosterone enanthate (comparison) +181%
Trenbolone +178%
Myostatin protein6 otherwise slows muscle growth
Testosterone enanthate (comparison) +159%
Trenbolone +169%

Rats, 41 animals in four groups. Testosterone was given in a much higher amount than trenbolone. Despite more myostatin the muscle grew under both hormones.

Prostate (rats)45

Change in prostate mass compared with sham-operated rats

Young rats, highest level4 castrated or intact, 29 days
Testosterone enanthate (comparison) +84%
Trenbolone +68%
Older castrated rats5 5 weeks, one trenbolone level
Trenbolone -20%

Low trenbolone levels kept prostate and haemoglobin at the sham level. In the older rats the value -20 is not statistically significant, testosterone nearly doubled the prostate there. Not transferable to humans.

Body and blood lipids (rats)7

Non-castrated rats, 6 weeks of trenbolone via a pump under the skin

Fat mass7
No hormone (comparison) +34%
Trenbolone -37%
Lean mass7
Trenbolone +11%
Triglycerides7 vs control
Trenbolone -62%
HDL cholesterol7 vs control
Trenbolone -57%
LDL cholesterol7 vs control
Trenbolone -78%

12 rats. The control animals gained fat over 6 weeks, under trenbolone fat mass fell. The prostate grew benignly, the body's own sex hormones were suppressed. Rat values for blood lipids do not transfer to humans.

Glass heart model with red vessels next to a rack full of sample tubes on a lab trolley
Data come from animal studies and surveys, not from human trials. Symbolic image.

Research status

Where the research stands

There is no registered human trial of trenbolone. The data on Tren Hex come from animal studies, lab experiments and surveys of users. As of 26 Oct 2026. 12

  1. Preclinical Rats: muscle, bone, fat and prostate
  2. Phase 1 no registered trial
  3. Phase 2 no registered trial
  4. Phase 3 no registered trial
  5. Approval not yet
Not approved. ChEMBL records no approval for trenbolone acetate, trenbolone is used in cattle fattening.12

So far there is no registered trial in humans. 12

Side effects

  • Prolactin/progestin - cabergoline as countermeasure.
  • Night sweats, sleep issues, aggression.
  • Unfavorable lipids, blood pressure.
  • Strong HPTA suppression - long PCT wait due to the long ester.

Tolerability

Self-reported concerns in a survey

Out of 100 men, how many reported the concern in an online survey. Self-report, no medical measurement, no placebo.

54 of 100 With trenbolone (237 men)
31 of 100 Other anabolic steroids without trenbolone (909 men)
Event With trenbolone (237 men)Other anabolic steroids without trenbolone (909 men)
Concern about the heart10 54%31%
Hair loss10 43%28%
Concern about the liver10 42%22%
Gynaecomastia10 33%21%
Restlessness and irritability10 29%13%
Decreased sexual function10 25%15%
Anger and aggression10 21%9%

Values from the tables of the study (full text), rounded in the chart. The trenbolone group also took oral anabolic steroids far more often (79.7 vs 38.4 percent), so a concern cannot be assigned to one compound with certainty. Several concerns occurred together more often with trenbolone.10

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
Store the oil solution at room temperature and protected from light. Symbolic image.
Level · Tren Hex (Parabolan)

How the level builds up

Two doses per week: each dose adds to what is left of the previous one.

Lexicon: Intramuscular (subQ possible), 2x per week
Peak 4.03×Trough 3.03×
Day 35 · 11. dose
3.85× of the first dose
Plateau
from Day 35

96 % of the plateau after dose 11

Peak
4.03×

of the first dose

Trough
3.03×

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 a different path: all in the TPD lexicon.

Tren Hex (Parabolan)
Trenbolone Acetate Short ester, same compound Trenbolone Enanthate Long ester, same compound TrenMix 150 Blend of several trenbolone esters TrenMix 200 Acetate plus enanthate TriTren 225 Three trenbolone esters Methyltrenbolone (Metribolone) Methylated trenbolone, a compound of its own Deca (Nandrolone Decanoate) 19-nor like trenbolone, with progesterone activity Cabergoline Mentioned in the lexicon under prolactin

FAQ

Common questions about Tren Hex (Parabolan)

Short answers, each backed by the sources below.

Is Tren Hex approved for humans?

No. ClinicalTrials.gov lists not a single trial with trenbolone (as of 26 October 2026), ChEMBL records no approval for trenbolone acetate. Trenbolone is used in cattle fattening, according to one paper in over 20 million cattle a year. Everything here is the state of research, not a recommendation.12137

How does Tren Hex differ from trenbolone acetate?

Only the ester. After it is split off the same trenbolone acts in both cases, the longer ester releases it more slowly from the oil depot. A larger part of the molecule's weight is ester: about 66 percent is trenbolone, with the acetate about 87 percent. There is no human study comparing the esters.141

How does trenbolone act at the receptors?

In the lab trenbolone bound the human androgen receptor about as strongly as DHT and the (bovine) progesterone receptor slightly more strongly than progesterone. A review cites about three times the binding of testosterone. Unlike testosterone it is not converted into stronger androgens. In cell experiments it also blocked the effect of glucocorticoids.819

What do the animal studies show?

In castrated rats the muscle fibre cross-section grew by 94 percent under trenbolone enanthate, satellite cells by 178 percent. Bone density was preserved after castration, the femoral neck was 28 percent stronger. Low levels kept the prostate at the sham level, the highest level enlarged it by 68 percent. In non-castrated rats fat mass fell by 37 percent in 6 weeks.6547

What do users report in surveys?

In the Global Drug Survey 2024, 237 men using trenbolone reported almost all queried concerns more often than 909 men using other anabolic steroids, for example concern about the heart (54.4 vs 31.2 percent), restlessness and irritability (29.1 vs 12.9 percent) as well as anger and aggression (21.1 vs 9.2 percent). In a second survey of 282 men a higher amount of trenbolone was linked to more verbal aggression.1011

Which side effects are described?

For anabolic steroids in general, reviews describe falling HDL cholesterol, rising blood pressure, more aggression and a suppressed hormone axis that often takes months to recover after stopping. In rats on trenbolone the body's own sex hormones were suppressed and the prostate grew benignly. In the lab trenbolone also binds to the progesterone receptor, the lexicon covers this under prolactin.378

Glossary

Terms explained briefly

Dotted words in the text open these explanations directly.

19-nor anabolic
Anabolic steroid lacking one carbon (position 19) in its skeleton, like nandrolone and trenbolone.
5-alpha reductase
Enzyme that converts testosterone to DHT, for example in the prostate. Trenbolone is not strengthened 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 an androgen to oestrogen by the enzyme aromatase. According to reviews this hardly happens with trenbolone.
Blood lipids (HDL, LDL)
HDL counts as protective, LDL as unfavourable cholesterol. In humans anabolic steroids mostly lower HDL.
Depot
The oil solution stays in the tissue after the injection and releases the compound over days.
Ester
An attached acid chain. It makes the compound oil-soluble and sets how slowly it is released from the depot. It is split off in the body.
Hormone axis (HPTA)
Hypothalamus, pituitary and testes together control the body's own testosterone production. Anabolic steroids from outside suppress this axis.
PCT
Post-cycle therapy: the time after stopping in which the body's own hormone axis is meant to recover.
Progesterone receptor
Receptor of the hormone progesterone. In the lab trenbolone also binds to it.
Prolactin
Pituitary hormone. If it stays high it can disturb libido and erection.
Satellite cells
Stem cells on the muscle. They help muscle fibres grow and repair.

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 14 sourcesHide sources 11 Studies1 Trial registry2 Database checked 26 Oct 2026

Studies

  1. Review: trenbolone is strongly anabolic but less androgenic and estrogenic

    Yarrow et al., Steroids, 2010

    DOI 10.1016/j.steroids.2010.01.019 PMID 20138077
    Checked 26 Oct 2026 via doi.org, Crossref, PubMed
  2. 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
  3. Effects of androgenic-anabolic steroids in athletes, review

    Hartgens und Kuipers, Sports Medicine, 2004

    DOI 10.2165/00007256-200434080-00003 PMID 15248788
    Checked 26 Oct 2026 via doi.org, Crossref, PubMed
  4. Trenbolone enanthate in rats: muscle, bone, fat, haemoglobin and prostate

    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
  5. Trenbolone enanthate preserves bone density in older castrated rats

    McCoy et al., Bone, 2012

    DOI 10.1016/j.bone.2012.07.008 PMID 22842328
    Checked 26 Oct 2026 via doi.org, Crossref, PubMed
  6. Testosterone and trenbolone enanthate: muscle fibres, satellite cells and myostatin (rats)

    Dalbo et al., Andrologia, 2017

    DOI 10.1111/and.12622 PMID 27246614
    Checked 26 Oct 2026 via doi.org, Crossref, PubMed
  7. Trenbolone in non-castrated rats: body composition, blood lipids, prostate

    Donner et al., Steroids, 2015

    DOI 10.1016/j.steroids.2014.12.017 PMID 25554582
    Checked 26 Oct 2026 via doi.org, Crossref, PubMed
  8. Binding of trenbolone to androgen and progesterone receptors (lab)

    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
  9. 17β-trenbolone in the lab and in rats: androgen receptor and glucocorticoids

    Wilson et al., Toxicological Sciences, 2002

    DOI 10.1093/toxsci/70.2.202 PMID 12441365
    Checked 26 Oct 2026 via doi.org, Crossref, PubMed
  10. Survey of 1,146 men using anabolic steroids: concerns with and without trenbolone

    Bonenti et al., Drug and Alcohol Review, 2026

    DOI 10.1111/dar.70162 PMID 42037159
    Checked 26 Oct 2026 via doi.org, Crossref, PubMed, PMC (Volltext)
  11. Trenbolone, psychological distress and aggression in 282 men (survey)

    Piatkowski et al., International Journal of Drug Policy, 2024

    DOI 10.1016/j.drugpo.2024.104636 PMID 39486244
    Checked 26 Oct 2026 via doi.org, Crossref, PubMed

Trial registry

  1. Search on ClinicalTrials.gov (no trial with trenbolone)

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

    Checked 26 Oct 2026 via ClinicalTrials.gov API v2

Database

  1. Trenbolone acetate in ChEMBL (no approval recorded)

    ChEMBL, EMBL-EBI (CHEMBL1698011)

    Checked 26 Oct 2026 via ChEMBL
  2. Molar mass of trenbolone hexahydrobenzylcarbonate in PubChem

    PubChem, U.S. National Library of Medicine (CID 20055297, Trenbolon CID 25015, Trenbolon Acetat CID 66359)

    Checked 26 Oct 2026 via PubChem

In the shop

Tren Hex (Parabolan) in the catalog

Sizes, prices and shipping times are on the product page.

To the product