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Muscle & performance

Testosterone Enanthate

The long testosterone ester - the standard base of almost every research protocol.

2 min read 16 sources

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Still from the explainer video about this entry
Approved · since 1953Lab tested in the shop

No time to read it all? The video sums up the whole entry in about a minute, from how it works to the studies and storage.

Summary

At a glance

Sources checked on 25 Oct 2026

Back to baseline
9 days

After one injection: peak level at 8 to 24 hours, back to baseline after 9 days8

Fat-free mass in 10 weeks
+6.1 kg

Healthy men with strength training, randomised trial with 43 participants1

Fat-free mass, highest level
+7.9 kg

20 weeks, highest of five study doses (the two levels below +5.2 and +3.4 kg)2

Azoospermia within 6 months
65 %

WHO study with 271 men: cumulative share without detectable sperm6

Phase 3 in the registry
5 trials

4 of them completed, one of them phase 2/3, as of 25 Oct 202615

  • Testosterone Enanthate is testosterone with an enanthate ester. After the injection it is released from the oil depot over days and acts on the androgen receptor.816
  • In the best-known trial fat-free mass, muscle size and strength rose clearly in healthy men within 10 weeks, most of all with strength training.1
  • The effect depends on the amount: fat-free mass, haemoglobin and strength rose with the testosterone level while fat mass and HDL cholesterol fell.25
  • The body's own hormone axis is suppressed. LH and FSH drop, sperm production stops in many men and recovered within months after stopping in the trials.76
  • Given subcutaneously Testosterone Enanthate also reached steady levels in trials. According to ChEMBL it has been an approved drug since 1953. Everything here is the state of research, not a recommendation.101216
Profile

Updated June 2026

How long does it stay in the body?

Share left after one dose, calculated with a half-life of ~4.5 days

Half-life ~4.5 days
After 9 days: 25 %
Day 5 · 46 %Day 9 · 25 %Day 14 · 11.6 %Day 23 · 2.9 %

Simplified model without an absorption phase, half-life from the TPD lexicon. The lexicon gives 4 to 5 days, we calculate with the middle.

Class
Testosterone ester

long-acting

Use
Intramuscular or subcutaneous

1-2x per week

Half-life
about 4-5 days
WADA
banned

anabolic

Sizes
4 sizes

250mg/ml, 300mg/ml, 30ml/250mg/ml …

Contents 14 sections
  1. At a glance
  2. What is Testosterone Enanthate?
  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 Testosterone Enanthate?

Testosterone Enanthate (Test E) is testosterone with an attached enanthate ester. The ester slows release from the injection depot, so the compound enters the blood gradually over days. That makes Test E one of the longest-running and best-studied testosterone esters.

It is the classic base of almost every anabolic protocol, from low-dose substitution to the classic building cycle. This information is for research and educational purposes only. No medical advice.

Comparison

Short and long esters

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

Short ester Testosterone Propionate AR Medium ester Testosterone Phenylpropionate AR
Long ester Testosterone Enanthate AR
Long ester Testosterone Cypionate AR Very long ester Testosterone Decanoate AR Very long ester Testosterone Undecanoate AR

How it works

Testosterone binds the androgen receptor in muscle and other tissues and increases protein synthesis, nitrogen retention and red blood cell formation. Part of it is converted to estradiol via aromatase, which is why estrogen management (e.g. an aromatase inhibitor) belongs in the picture at higher doses.

Where it acts

One receptor, several organs

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

  1. Hypothalamus and pituitary

    LH and FSH suppressed, below 0.5 U/L after 4 weeks7

    Observed in trials
  2. Blood

    Haemoglobin and haematocrit rose with the dose, more in older men5

    Observed in trials
  3. Liver and blood lipids

    HDL cholesterol fell as testosterone levels rose2

    Observed in trials
  4. Skeletal muscle

    Muscle size in arms and legs and strength increased, most with training1

    Observed in trials
  5. Fat tissue

    Fat mass fell with higher doses, in the thigh mostly between the muscles4

    Observed in trials
  6. Testes

    Sperm production suppressed, recovered within months after stopping6

    Observed in trials

Targets in the ChEMBL database16

Compound CHEMBL1200335: one recorded mechanism, agonist with direct binding to the human receptor.

Androgen receptor
Gene
AR
UniProt
P10275
ChEMBL
CHEMBL1871
Action
Agonist, direct binding
Blue 3D molecules flowing out of a glass vessel over translucent muscle fibres, one gliding through a glass ring
The ester makes testosterone oil-soluble. It is released from the oil depot over days. Symbolic image.

How to use it

Dosing. Loading the dosing information …
Glass vial with golden oil and the black TPD label, next to a disposable syringe on a bright surface
For oil: a thicker needle to draw up, a thinner one to inject. 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
Testosterone enanthate vial with a 3 ml syringe on a light blue cloth and a closed notebook
Symbolic image.

What the research shows

The famous Bhasin study (NEJM, 1996) showed that healthy men on 600mg testosterone enanthate per week for 10 weeks gained marked fat-free mass, muscle size and strength - even without training, more so with training. It remains one of the cleanest demonstrations of testosterone's anabolic effect.

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.

Fat-free mass after 20 weeks2

Gain in kg in the three higher of five dose levels, the body's own production was switched off with medication

Trial with five dose levels2 20 weeks
Level 3 of 5 +3.4 kg
Level 4 of 5 +5.2 kg
Level 5 of 5 (highest, 600 mg per week) +7.9 kg

The two lowest levels are not shown here. Fat mass and HDL cholesterol fell as levels rose while haemoglobin went up.

Suppressed sperm production67

Share of men, trials on hormonal male contraception with weekly injections

WHO study, 10 centres6 271 men, cumulative at 6 months
No detectable sperm 65%
Study in Edinburgh7 33 men, after 20 weeks
No detectable sperm 55%
Severely reduced 45%

After stopping, the WHO study saw a median of 3.7 months until at least 20 million sperm per ml returned and 6.7 months until baseline. Research data, not a contraceptive.

Subcutaneous use in trials121310

Share of participants, weekly injection under the skin

52-week trial12 150 men with testosterone deficiency, week 12
Level in target range 93%
26-week trial13 133 men with testosterone deficiency, week 26
Level in target range 83%
Clinic review10 63 people, 22 of them previously intramuscular
Level in target range 100%
Prefer subcutaneous 100%

Target range defined differently per trial: 300 to 1,100 ng/dl on average (52 weeks), 300 to 650 ng/dl as trough (26 weeks) or the normal male range. Abstract values 92.7 and 83.2 percent, rounded in the chart. The clinic review used testosterone cypionate or enanthate.

Glass organ model and a glass dumbbell on a stainless steel lab trolley
Symbolic image.

Research status

Where the research stands

Registered trials with status, participants and results. As of 25 Oct 2026. 15

  1. Preclinical Release in an animal model (monkeys)
  2. Phase 1 5 trials, 5 completed
  3. Phase 2 13 trials, 9 completed
  4. Phase 3 5 trials, 4 completed
  5. Approval since 1953
519 participants in phase 3 Planned figures for running trials Approved: ChEMBL lists Testosterone Enanthate with phase 4 as the highest phase and first approval in 1953.16
Show all 18 phase 2 and 3 trials on a timelineHide timeline 13 completed 5 running 1 with results
Phase 2
Phase 3

Bar: start to primary endpoint (planned for running trials). Green = completed, blue = progress until 25 Oct 2026. Phase 1: 5 trials on safety and pharmacokinetics, not shown as bars.

Side effects

  • Estrogen-related: water retention, gyno risk with high aromatization.
  • Hematocrit: can rise, monitor blood thickness.
  • HPTA suppression: natural production is suppressed, mind the PCT topic.
  • Androgenic: acne, hair loss in predisposed individuals.

Tolerability

Frequency in the 26-week trial (subcutaneous)

Out of 100 participants, how many had the event over 26 weeks. One group, no placebo.

26 of 100 Subcutaneous, all participants
Event Subcutaneous, all participants
Any adverse drug reaction13 26%
Raised haematocrit (52% or more)13 8%
Bleeding at the injection site13 5%
Bruising at the injection site13 3%
Raised PSA13 3%

Abstract values 25.6, 7.5, 4.5, 3.0 and 3.0 percent, rounded in the chart. One group without placebo. Blood pressure rose slightly on average. In the 52-week trial 30 of 150 men stopped because of raised haematocrit, high blood pressure or PSA.1312

Storage

Store the oil solution at room temperature, protected from light - no fridge needed. Keep original container closed, out of reach of children.

Four glass vials with golden oil and a light blue towel on a white shelf
Oil solution at room temperature and protected from light, no fridge needed. Symbolic image.

Related

Related compounds

Same receptors or blends with Testosterone Enanthate: all in the TPD lexicon.

Testosterone Enanthate
Testosterone Cypionate Long ester, nearly identical Testosterone Propionate Short ester, more frequent doses Testosterone Phenylpropionate Medium-length ester Testosterone Decanoate Very long ester Testosterone Undecanoate Very long ester, also as a tablet Tri-Test Contains Testosterone Enanthate plus two more esters Test/Deca Mix 500 Contains Testosterone Enanthate plus nandrolone decanoate Test/EQ Mix 400 Contains Testosterone Enanthate plus boldenone undecylenate Test/Tren Long 300 Contains Testosterone Enanthate plus trenbolone enanthate

FAQ

Common questions about Testosterone Enanthate

Short answers, each backed by the sources below.

How long does one injection last?

The oil solution forms a depot in muscle or under the skin, from which the ester is released slowly. In a comparison study testosterone peaked 8 to 24 hours after the injection (four to five times the starting level) and was back at baseline after 9 days. With weekly injections the level before each injection rose to 2.5 times baseline over about 12 weeks.87

Is Testosterone Enanthate approved?

Yes. The ChEMBL database lists Testosterone Enanthate as an approved drug with first approval in 1953. Trials are still running on ClinicalTrials.gov, among them on subcutaneous use in adolescents and on very high testosterone levels in prostate cancer. Everything here is the state of research, not a recommendation.1615

What did the Bhasin study show?

43 healthy men received Testosterone Enanthate or placebo once a week for 10 weeks, with or without strength training. Without training bench-press strength rose by 9 kg on testosterone and fell by 1 kg on placebo. With training they gained 22 kg in bench-press strength and 6.1 kg of fat-free mass. Mood and behaviour did not change in any group.1

Does the effect depend on the amount?

Yes, clearly. In a trial with five dose levels over 20 weeks (the body's own production was switched off with medication) fat-free mass rose by 3.4, 5.2 and 7.9 kg in the three higher levels. Fat mass and HDL cholesterol fell as levels rose while haemoglobin went up. Older men responded just as well but had side effects more often at the high levels.235

Subcutaneous or intramuscular?

Both have been studied. Given weekly under the skin, Testosterone Enanthate reached normal average levels with little fluctuation. In a clinic review of 63 people (cypionate or enanthate) all reached normal male levels and all 22 who had injected intramuscularly before preferred subcutaneous. In a 52-week trial more than 95 percent reported no pain at the injection. A model calculated about 76 to 78 percent of the intramuscular average level for the same amount given subcutaneously.11101214

What happens to the body's own hormone production and fertility?

Testosterone from outside suppresses the hormone axis. In one trial LH fell measurably within 24 hours of the first injection, LH and FSH were below 0.5 U/L after 4 weeks. In the WHO study a cumulative 65 percent had no detectable sperm after 6 months. After stopping it took a median of 3.7 months until at least 20 million sperm per ml returned and 6.7 months until baseline.76

Which side effects were seen?

In a 26-week trial with subcutaneous use 25.6 percent had an adverse drug reaction, most often raised haematocrit (7.5 percent), along with bleeding or bruising at the injection site and raised PSA. Blood pressure rose slightly on average. Haemoglobin and haematocrit rise with the dose, more so in older men. In one trial estradiol rose similarly to testosterone.1357

Which trials are still running?

As of 25 October 2026 five trials with Testosterone Enanthate are recruiting on the registry. Three of them study prostate cancer, one spinal cord injury and one subcutaneous use in adolescents with hypogonadism (planned end 2028). Several prostate cancer trials deliberately test very high testosterone levels (bipolar androgen therapy).15

Glossary

Terms explained briefly

Dotted words in the text open these explanations directly.

Androgen receptor
Protein inside the cell that testosterone binds to. Genes are then read, for example for muscle building.
Aromatase
Enzyme that converts part of the testosterone into estradiol.
Azoospermia
No sperm detectable in the ejaculate.
Depot
The oil solution stays in the tissue after the injection and releases the compound over days.
Ester
An attached fatty acid chain. It makes testosterone oil-soluble and sets how slowly it is released from the depot. It is split off in the blood.
Estradiol
The main oestrogen. In men it is also made from testosterone and rises with the testosterone level.
Fat-free mass
Body weight without fat: muscle, bone, organs and water.
Haematocrit
Share of red blood cells in the blood. If it rises a lot, the blood gets thicker.
Hormone axis (HPTA)
Hypothalamus, pituitary and testes together control the body's own testosterone production. Testosterone from outside suppresses this axis.
Intramuscular
Into the muscle, for example the glute or thigh.
LH and FSH
Pituitary hormones. LH drives testosterone production in the testes, FSH drives sperm production.
Placebo
Dummy preparation without active substance. Comparing against it shows what is due to the substance itself.
Subcutaneous
Into the fat layer just under the skin.
Trial phases
Phase 1 tests tolerability in a few people, phase 2 looks for the dose, phase 3 confirms benefit and safety in many. Phase 4 runs after approval.

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.

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

Evidence

Sources

Show all 16 sourcesHide sources 14 Studies1 Trial registry1 Database checked 25 Oct 2026

Studies

  1. Supraphysiologic testosterone doses, muscle size and strength in healthy men

    Bhasin et al., New England Journal of Medicine, 1996

    DOI 10.1056/NEJM199607043350101 PMID 8637535
    Checked 25 Oct 2026 via doi.org, Crossref, PubMed
  2. Dose response in young men, five levels over 20 weeks

    Bhasin et al., American Journal of Physiology: Endocrinology and Metabolism, 2001

    DOI 10.1152/ajpendo.2001.281.6.E1172 PMID 11701431
    Checked 25 Oct 2026 via doi.org, Crossref, PubMed
  3. Dose response in older compared with young men

    Bhasin et al., Journal of Clinical Endocrinology and Metabolism, 2005

    DOI 10.1210/jc.2004-1184 PMID 15562020
    Checked 25 Oct 2026 via doi.org, Crossref, PubMed
  4. Fat distribution by dose

    Woodhouse et al., Journal of Clinical Endocrinology and Metabolism, 2004

    DOI 10.1210/jc.2003-031492 PMID 14764787
    Checked 25 Oct 2026 via doi.org, Crossref, PubMed
  5. Red blood cell production (haemoglobin, haematocrit) by dose

    Coviello et al., Journal of Clinical Endocrinology and Metabolism, 2008

    DOI 10.1210/jc.2007-1692 PMID 18160461
    Checked 25 Oct 2026 via doi.org, Crossref, PubMed
  6. WHO study: sperm production under weekly injections

    WHO Task Force on Methods for the Regulation of Male Fertility, The Lancet, 1990

    DOI 10.1016/0140-6736(90)92416-F PMID 1977002
    Checked 25 Oct 2026 via doi.org, Crossref, PubMed (Titel und Seiten, Datensatz ohne DOI)
  7. Levels and hormone axis with weekly injections

    Anderson and Wu, Journal of Clinical Endocrinology and Metabolism, 1996

    DOI 10.1210/jcem.81.3.8772547 PMID 8772547
    Checked 25 Oct 2026 via doi.org, Crossref, PubMed
  8. Level over time after one injection

    Schürmeyer and Nieschlag, International Journal of Andrology, 1984

    DOI 10.1111/j.1365-2605.1984.tb00775.x PMID 6434435
    Checked 25 Oct 2026 via doi.org, Crossref, PubMed
  9. Release in an animal model compared with undecanoate

    Partsch et al., European Journal of Endocrinology, 1995

    DOI 10.1530/eje.0.1320514 PMID 7711892
    Checked 25 Oct 2026 via doi.org, Crossref, PubMed
  10. Subcutaneous instead of intramuscular, clinic review

    Spratt et al., Journal of Clinical Endocrinology and Metabolism, 2017

    DOI 10.1210/jc.2017-00359 PMID 28379417
    Checked 25 Oct 2026 via doi.org, Crossref, PubMed
  11. Levels with weekly subcutaneous use (phase 2)

    Kaminetsky et al., Sexual Medicine, 2015

    DOI 10.1002/sm2.80 PMID 26797061
    Checked 25 Oct 2026 via doi.org, Crossref, PubMed
  12. Subcutaneous use over 52 weeks

    Kaminetsky et al., Journal of Urology, 2019

    DOI 10.1016/j.juro.2018.09.057 PMID 30296416
    Checked 25 Oct 2026 via doi.org, Crossref, PubMed
  13. Safety of subcutaneous use over 26 weeks (phase 3)

    Gittelman et al., Journal of Sexual Medicine, 2019

    DOI 10.1016/j.jsxm.2019.08.013 PMID 31551193 NCT02504541
    Checked 25 Oct 2026 via doi.org, Crossref, PubMed
  14. Model: subcutaneous and intramuscular compared

    Vogiatzi et al., Journal of the Endocrine Society, 2023

    DOI 10.1210/jendso/bvad059 PMID 37180212
    Checked 25 Oct 2026 via doi.org, Crossref, PubMed

Trial registry

  1. All trials on ClinicalTrials.gov

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

    Checked 25 Oct 2026 via ClinicalTrials.gov API v2

Database

  1. Mechanism and approval in ChEMBL

    ChEMBL, EMBL-EBI (CHEMBL1200335)

    Checked 25 Oct 2026 via ChEMBL

In the shop

Testosterone Enanthate in the catalog

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