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Sustanon 300

Testosterone blend of several esters at a combined 300 mg/ml, the stronger version of classic Sustanon.

3 min read 15 sources

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Glossy blue 3D steroid molecule surrounded by detachable ester chains of different length above a white podium with a glowing light-blue ring, a golden oil drop beside it, symbolic image for Sustanon 300
Components approved · no study of this strength

Summary

At a glance

Sources checked on 25 Oct 2026

In the classic blend
4 esters

Propionate, phenylpropionate, isocaproate and decanoate, each detectable in blood. The ratio here is not stated by the manufacturer2

Protein gain, classic blend
+8.3 g per day

Older men with strength training over 6 weeks, +1.9 g with placebo and training5

Bone density, classic blend
+5 %

21 men with osteoporosis, 6 months, injection every 2 weeks, open study6

Esters detectable in blood
14 days

Dried blood spots: all esters for at least 5 days, three of the four for up to 14 days4

  • Sustanon 300 blends several testosterone esters in one oil, four according to the product information, more concentrated than the classic blend. Short esters reach the blood quickly while long ones hold the level. All release the same compound, which acts on the androgen receptor.215
  • There is no study on Sustanon 300 itself. With the classic four-ester blend, older men doing strength training gained fat-free mass, muscle thickness and strength more than training alone within 6 weeks while fat mass fell.5
  • With the classic blend lumbar spine bone density rose by about 5 percent in two studies, in men with osteoporosis and in men taking cortisone.67
  • The body's own hormone axis is suppressed: LH and testicular markers fell in young men and recovered after stopping. Red blood cell values shift.83
  • The effect depends on the amount: fat-free mass and haemoglobin rose with the testosterone level while HDL cholesterol fell. Everything here is the state of research, not a recommendation.12
Profile

Updated October 2026

Class
Testosterone ester blend

anabolic steroid

Contents
Several test esters

300 mg/ml combined

Form
Oil, 10 ml

3,000 mg

Use
Intramuscular

2x per week

WADA
Banned

S1, anabolic agents

Sizes
10 ml

1 size in the shop

Contents 15 sections
  1. At a glance
  2. What is Sustanon 300?
  3. How it works
  4. Use and dosing
  5. Injection
  6. What the research shows
  7. Research status
  8. Side effects
  9. Practice
  10. Storage
  11. PCT / after coming off
  12. Related compounds
  13. FAQ
  14. Glossary
  15. Sources

What is Sustanon 300?

Sustanon 300 is a ready-made oil solution that combines several (four, according to the product information) testosterone esters in one vial, 300 mg per ml in total. A vial holds 10 ml, so 3,000 mg. The idea is the same as classic Sustanon 250: short esters act fast while long esters hold the level.

The manufacturer does not state the exact ester ratio. For comparison, classic Sustanon 250 contains 30mg propionate, 60mg phenylpropionate, 60mg isocaproate and 100mg decanoate per ml.

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

Comparison

One ester or four

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 Very long ester Testosterone Decanoate AR Four esters, classic blend Sustanon 250 AR
Four esters per product information, more concentrated Sustanon 300 AR
Long single ester Testosterone Enanthate AR

Simplified: the ester only sets how fast testosterone is released from the depot. At the receptor it is always the same testosterone. 211

How it works

All esters release the same compound: testosterone. It binds the androgen receptor and raises protein synthesis, nitrogen retention and red blood cell production. The blend is only a release trick; the active compound is always the same.

Part of the testosterone is converted to estradiol by aromatase and part to DHT. That brings the usual estrogen and androgen topics. Because short and long esters are mixed, levels rise quickly after a dose and then fall more slowly than with a short single ester.

Where it acts

Where the classic blend acted in studies

Tap a point or a card. Grey = observed in studies, all via the androgen receptor.

  1. Pituitary

    LH fell in young men, back to baseline after stopping8

    Observed in trials
  2. Testes

    Leydig cell marker INSL3 fell, recovered after stopping8

    Observed in trials
  3. Skeletal muscle

    More fat-free mass, muscle thickness and strength than with training alone5

    Observed in trials
  4. Fat tissue

    Total fat mass fell within 6 weeks5

    Observed in trials
  5. Bone

    Spine bone density +5 percent, bone breakdown slowed6

    Observed in trials
  6. Blood

    Red blood cell values shifted, more young red blood cells3

    Observed in trials

Targets in the ChEMBL database15

Compound CHEMBL386630: one recorded mechanism, Agonist, direct binding (testosterone).

Androgen receptor
Gene
AR
UniProt
P10275
ChEMBL
CHEMBL1871
Action
Agonist, direct binding (testosterone)
Golden oil depot sphere beside translucent glass muscle fibres, steroid molecules leaving at staggered times and docking on the fibres
Esters of different length release testosterone at staggered times; it acts on the androgen receptor. Symbolic image.

Use and 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
Small amber glass vial with clear, slightly yellowish oil and a grey stopper, a capped syringe beside it on a white table
Ready-to-use oil solution, no mixing. Symbolic image.

Injection

The oil is ready to use and is not mixed. Intramuscular injection into the glute, thigh or shoulder is recommended; disinfect the site and rotate regularly.

  • Thicker needle to draw, thinner needle to inject.
  • The short ester component irritates subcutaneous fat more, so subcutaneous only in small amounts and if well tolerated.
  • Mild soreness at the site during the first one to two days is common.

What the research shows

For the classic Sustanon blend there is doping control data: Forsdahl and colleagues (2015) gave volunteers a single dose of 30mg propionate, 60mg phenylpropionate, 60mg isocaproate and 100mg decanoate. All esters were detectable in blood and the detection window depended on the ester.

Weinbauer and colleagues (2003) showed in primates that at the same amount of testosterone, the release profile and aromatization shape the effects more than the total dose. For the effect of testosterone itself, Bhasin's dose-response trial (2001) is the usual reference: muscle mass and strength rose with the dose while HDL fell.

The Endocrine Society (2013) summarizes the risks of performance-level dosing. There are no controlled studies on Sustanon 300 itself.

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.

Protein gain in muscle per day5

Older men (65 to 75 years), 6 weeks of strength training, injection every 2 weeks, 9 participants each

Randomised double-blind trial5 Net gain from synthesis minus breakdown
Placebo with training +1.9 g
Classic blend +8.3 g

Muscle protein synthesis ran at 2.13 percent per day with the blend and 1.34 percent with placebo. Breakdown rose too, but on balance clearly more protein stayed in the muscle.

Lumbar spine bone density67

Change in percent on the classic four-ester blend

Men with osteoporosis6 21 men, 6 months, no comparison group
Classic blend +5.0%
Men on cortisone7 15 men with asthma, 12 months, crossover
Classic blend +5.0%

Abstract values 5 and 5.0 percent. In the cortisone study bone density did not change without testosterone; in the control phase fat mass rose and lean mass fell, both reversed with testosterone.

Flagged profiles after two injections3

Share of the 9 men on the blend, randomised against placebo

Healthy men3 Measurements 1 to 14 days after each injection
Steroid profile flagged 100.0%
Blood profile flagged 66.7%

Steroid profile flagged in 9 of 9, blood profile in 6 of 9 (shown as a share). The share of young red blood cells (reticulocytes) showed the use best, mainly 3 to 10 days later.

Glass display case with three frosted glass muscle sculptures of rising size on a white plinth
More compound per ml, the same testosterone. Symbolic image.

Research status

Where the research stands

There is no study on Sustanon 300 itself. Shown are registered trials with the classic four-ester blend (Sustanon 250), mostly as testosterone replacement in hormone deficiency. As of 25 Oct 2026. 14

  1. Preclinical Animal model (rats): testes and sperm production
  2. Phase 1 1 trial on components, 0 completed
  3. Phase 2 no registered trial
  4. Phase 3 1 trial on components, 1 completed
  5. Approval no study of this strength
0 participants in phase 3 Components approved: ChEMBL lists testosterone and testosterone propionate as approved drugs and the classic four-ester blend appears in phase 4 trials. There is no registry entry for Sustanon 300 at this strength.15
Show all 13 trials on a timelineHide timeline 12 completed 1 running 0 with results
Phase 3
Phase 4
Without phase

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

Side effects

Sustanon 300 carries the risk profile of every testosterone product. The higher concentration does not change that; it only means less volume per dose.

  • Estrogen: water retention, rising blood pressure, gyno risk.
  • Hematocrit: rises with the dose, keep an eye on the blood count.
  • HPTA suppression: your own testosterone production is suppressed and the testes can shrink.
  • Lipids: HDL falls.
  • Androgenic: acne, hair loss if predisposed.

Practice

Testosterone, estradiol, hematocrit, lipids and liver values are usually checked before the start and during a protocol. An aromatase inhibitor is used only according to bloodwork, not by default. Sustanon blends usually contain a long ester that keeps acting for a long time, so a post-cycle plan starts only with some distance to the last dose.

  • Banned in official competition (WADA S1).
Calm still life on a light wooden bench: dumbbells, a glass of water, a closed notebook with a pen and a bowl of fresh fruit in daylight

Storage

Keep the oil at room temperature, in the dark and closed. Do not put it in the fridge, as the compound can crystallize in the cold. Visible crystals dissolve when the vial is warmed and swirled until the solution is clear again.

Four glass vials with golden oil on a white shelf, a folded light-blue cloth beside them
Oil at room temperature, dark and closed. Symbolic image.

Related

Related compounds

Same receptors or blends with Sustanon 300: all in the TPD lexicon.

Sustanon 300
Sustanon 250 Classic four-ester blend, source of the studies here Sustanon 400 Same idea, more concentrated Supertest 450 Several esters, very highly concentrated Test Mix (high dose) Four esters, highly concentrated Tri-Test Three esters instead of four Testosterone Propionate Short ester on its own Testosterone Phenylpropionate Medium ester on its own Testosterone Decanoate Very long ester on its own Testosterone Enanthate Long single ester, best studied

FAQ

Common questions about Sustanon 300

Short answers, each backed by the sources below.

Why four esters in one injection?

Each ester is released from the oil depot at a different speed. After a single injection of the blend all four esters were detectable in blood and how long depended on the ester. A short ester like propionate kept levels above the normal range for about 48 hours in one study while long esters last much longer. At the receptor it is always testosterone in the end.210

Is Sustanon 300 approved?

For this strength we found neither a study nor a registry entry. The components are approved: the ChEMBL database lists testosterone and testosterone propionate as drugs and the classic four-ester blend appears in phase 4 trials on the registry. Testosterone is banned in sport. Everything here is the state of research, not a recommendation.1415

What does the higher concentration change?

There is more compound per ml, so the same amount needs less volume. At the receptor it is the same testosterone. In a trial with five dose levels over 20 weeks fat-free mass and haemoglobin rose with the testosterone level while HDL cholesterol fell. In monkeys the release profile shaped the effect more than the total amount.1211

What did the study with the classic blend show?

18 healthy men aged 65 to 75 did 6 weeks of weight training and got the classic four-ester blend or placebo every 2 weeks. With testosterone fat-free mass, leg mass, muscle thickness and strength rose more while fat mass fell. Net protein gain in muscle was 8.3 g per day versus 1.9 g with placebo. The study ran for only 6 weeks with 9 people per group.5

What happens to the body's own hormone production?

Testosterone from outside suppresses the hormone axis. In healthy young men LH and the testicular marker INSL3 fell on the blend and returned to baseline after stopping. In a rat study the testes shrank and sperm count, LH and FSH fell.89

How long do the esters stay in the blood?

In dried blood spots all four esters were measurable for at least 5 days after two injections and three of them for up to 14 days. Blood values changed too: the blood profile was flagged in 6 of 9 men, most clearly the share of young red blood cells 3 to 10 days after the injection.43

Which risks are known?

The Endocrine Society describes a higher risk of cardiovascular, liver, kidney, hormonal and psychiatric disorders for performance-enhancing drugs in high amounts. Controlled trials with such amounts hardly exist for ethical reasons. With the blend itself red blood cell values rise and the body's own hormone axis is suppressed.1338

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.
Bone density
Mineral content of bone, measured by X-ray (DXA). Low values mean osteoporosis.
Decanoate
The longest of the four esters. It holds the level the longest.
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.
Hormone axis (HPTA)
Hypothalamus, pituitary and testes together control the body's own testosterone production. Testosterone from outside suppresses this axis.
INSL3
Hormone from the Leydig cells in the testes. It shows how active the body's own testosterone production is.
Intramuscular
Into the muscle, for example the glute or thigh.
LH
Pituitary hormone that drives testosterone production in the testes. Testosterone from outside lowers it.
Placebo
Dummy preparation without active substance. Comparing against it shows what is due to the substance itself.
Propionate
The shortest of the four esters. It reaches the blood quickly and is gone quickly.
Reticulocytes
Young red blood cells. If their share rises, the bone marrow is making more blood.

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 15 sourcesHide sources 13 Studies1 Trial registry1 Database checked 25 Oct 2026

Studies

  1. Trenbolone review as a reference for the pharmacology of anabolic steroids (tissue selectivity)

    Yarrow et al., Steroids, 2010

    DOI 10.1016/j.steroids.2010.01.019 PMID 20138077
    Checked 25 Oct 2026 via doi.org, Crossref, PubMed
  2. Detection of the four esters in blood after one injection

    Forsdahl et al., Drug Testing and Analysis, 2015

    DOI 10.1002/dta.1914 PMID 26695486
    Checked 25 Oct 2026 via doi.org, Crossref, PubMed
  3. Blood values after two injections, randomised against placebo

    Solheim et al., Drug Testing and Analysis, 2020

    DOI 10.1002/dta.2803 PMID 32307878
    Checked 25 Oct 2026 via doi.org, Crossref, PubMed
  4. Esters in dried blood spots

    Solheim et al., Drug Testing and Analysis, 2022

    DOI 10.1002/dta.3030 PMID 33733610
    Checked 25 Oct 2026 via doi.org, Crossref, PubMed
  5. Older men, strength training with or without the testosterone blend

    Gharahdaghi et al., Journal of Cachexia, Sarcopenia and Muscle, 2019

    DOI 10.1002/jcsm.12472 PMID 31568675
    Checked 25 Oct 2026 via doi.org, Crossref, PubMed
  6. Men with osteoporosis, bone density and bone turnover

    Anderson et al., Journal of Bone and Mineral Research, 1997

    DOI 10.1359/jbmr.1997.12.3.472 PMID 9076591
    Checked 25 Oct 2026 via doi.org, Crossref, PubMed
  7. Men on cortisone, bone and body composition

    Reid et al., Archives of Internal Medicine, 1996

    DOI 10.1001/archinte.1996.00440100065008 PMID 8639011
    Checked 25 Oct 2026 via doi.org, Crossref, PubMed (Titel und Seiten, Datensatz ohne DOI)
  8. INSL3, testosterone and LH with a suppressed hormone axis

    Albrethsen et al., Journal of Clinical Endocrinology and Metabolism, 2023

    DOI 10.1210/clinem/dgad291 PMID 37235781
    Checked 25 Oct 2026 via doi.org, Crossref, PubMed
  9. Sperm production on the blend (rats)

    Kamali Hosseinzadeh et al., Translational Andrology and Urology, 2024

    DOI 10.21037/tau-24-397 PMID 39816223
    Checked 25 Oct 2026 via doi.org, Crossref, PubMed
  10. Level over time after testosterone propionate

    Fujioka et al., Journal of Clinical Endocrinology and Metabolism, 1986

    DOI 10.1210/jcem-63-6-1361 PMID 3782423
    Checked 25 Oct 2026 via doi.org, Crossref, PubMed
  11. Release profile rather than total dose (primates)

    Weinbauer et al., Journal of Andrology, 2003

    DOI 10.1002/j.1939-4640.2003.tb02739.x PMID 12954670
    Checked 25 Oct 2026 via doi.org, Crossref, PubMed
  12. 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
  13. Endocrine Society statement on health consequences

    Pope et al., Endocrine Reviews, 2014

    DOI 10.1210/er.2013-1058 PMID 24423981
    Checked 25 Oct 2026 via doi.org, Crossref, PubMed

Trial registry

  1. Trials with the classic blend 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 of testosterone in ChEMBL

    ChEMBL, EMBL-EBI (CHEMBL386630, Propionat CHEMBL1170)

    Checked 25 Oct 2026 via ChEMBL

In the shop

Sustanon 300 in the catalog

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

To the product