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Muscle & performance

Test Suspension

Ester-free testosterone in water - immediate effect, short, often used pre-workout.

1 min read 9 sources

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Glass vial of Test Suspension with a blue cap and TPD label on a white podium with a light blue ring of light, next to it a large blue 3D molecule with four fused rings in front of a bright lab background, symbolic image
Compound approved · testosterone since 1972 according to ChEMBL

Summary

At a glance

Sources checked on 26 Oct 2026

On the suspension without ester
0 trials

on the registry, testosterone itself has been approved for decades, as of 26 Oct 20268

Fat-free mass in 10 weeks
+6.1 kg

Testosterone enanthate with strength training, randomised trial with 43 healthy men1

Bench press in 10 weeks
+22 kg

Testosterone enanthate with strength training, 43 healthy men, +9 kg without training1

Even with a short ester
2 days

That is how long testosterone stayed above the lower normal limit after one injection of propionate, 14 days after enanthate5

At least one side effect
100 %

HAARLEM cohort with 100 users, 4 of them with a serious event7

  • Test Suspension is testosterone without an ester, as fine crystals spread in water instead of dissolved in oil. The crystals settle, so the vial is shaken before every draw.9
  • Without an ester there is no depot to slow the release. The sources checked here contain no measurements in humans of esterless testosterone given by injection. Even with the short propionate ester levels stayed raised for only one to two days.5
  • What testosterone does in muscle is shown by trials with esters: within 10 weeks fat-free mass, muscle size and strength rose, most of all with training and depending on the amount.13
  • Haemoglobin and haematocrit rise with the amount and the body's own hormone axis is suppressed. In a cohort of 100 users every one had at least one side effect.467
  • According to ChEMBL testosterone has been an approved compound since 1972. Everything here is the state of research, not a recommendation.9
Profile

Updated June 2026

Class
Ester-free testosterone

aqueous suspension

Use
Intramuscular

daily

Half-life
very short

hours

WADA
banned

anabolic

Sizes
100mg/ml

1 size in the shop

Contents 14 sections
  1. At a glance
  2. What is Test Suspension?
  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 Test Suspension?

Test Suspension is pure, ester-free testosterone in an aqueous suspension (no oil). Without an ester it rises immediately and clears very fast. That makes it the fastest form of testosterone there is - popular as a targeted pre-workout booster but impractical for stable levels.

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

Comparison

No ester to very long

The same compound at the same receptor, without an ester or with esters of different length, as stated in the TPD lexicon. Tap a card to open its entry.

No ester, in water Test Suspension AR
Short ester Testosterone Propionate AR Long ester Testosterone Enanthate AR Very long ester Testosterone Undecanoate AR

How it works

Identical testosterone action to all esters - just without delay. The immediate onset and fast clearance mean frequent, usually daily injections.

Where it acts

One receptor, several organs

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

  1. Testes

    Sperm production suppressed: no sperm in 65 percent after 6 months, recovery within months after stopping6

    Observed in trials
  2. Blood

    Haemoglobin and haematocrit rose with the testosterone dose, more in older men4

    Observed in trials
  3. Liver and blood lipids

    HDL cholesterol fell as testosterone levels rose3

    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 as testosterone levels rose3

    Observed in trials
  6. Skin

    Acne in 28 of 100 users, breast tissue growth in 197

    Observed in trials

Targets in the ChEMBL database9

Compound CHEMBL386630: 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 steroid molecules fly out of a cloud of fine droplets towards translucent glass muscle fibres and light up brightly there
Without an ester testosterone is not released with a delay. Symbolic image.

How to use it

Dosing. Loading the dosing information …
Glass vial of Test Suspension with a blue cap, clear liquid and white sediment, next to it a disposable syringe on a white table
The crystals settle, shake before every draw. 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

Testosterone research (Bhasin et al., NEJM 1996) applies here too - after immediate release the same testosterone acts. AAS pharmacology: Kicman 2008.

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.

Strength gain in 10 weeks1

Healthy men, weekly injection of testosterone enanthate or placebo, gain in kg

Bench press1 43 men, 10 weeks
Placebo without training -1 kg
Testosterone without training +9 kg
Testosterone with training +22 kg
Squat1 43 men, 10 weeks
Placebo without training +3 kg
Testosterone without training +16 kg
Testosterone with training +38 kg

Trial with testosterone enanthate alone, not with the blend. The abstract gives no figures for the placebo with training group. Mood and behaviour did not change in any group.

Fat-free mass after 20 weeks3

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

Trial with five dose levels3 61 young men, 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. Strength, haemoglobin and IGF-1 rose with the testosterone level while fat mass and HDL cholesterol fell. Trial with testosterone alone.

Bright desk by the window with a green plant, a stopwatch without numbers, books, a pen and a small frosted glass bicep figure
Studies exist on testosterone with an ester, not on the suspension. Symbolic image.

Research status

Where the research stands

Testosterone has been approved for decades. Counted are registered trials with esterless testosterone as an aqueous suspension, the registry finds none. As of 26 Oct 2026. 8

  1. Preclinical How anabolic steroids act in animals and cells (review)
  2. Phase 1 no registered trial
  3. Phase 2 no registered trial
  4. Phase 3 no registered trial
  5. Approval testosterone since 1972 according to ChEMBL
Approved: ChEMBL lists testosterone with phase 4 as the highest phase and first approval in 1972.9

The approval predates today's trial registries, so the register shows no current trial for this form. 8

Side effects

  • Estrogen-related: water retention, gyno risk.
  • Sting / irritation at the injection site pronounced (aqueous, crystalline).
  • Possible hematocrit rise.
  • HPTA suppression - PCT topic.

Tolerability

Frequency in the HAARLEM study

Out of 100 users, how many had the event. One cohort without a comparison group, participants chose compounds and amounts themselves.

100 of 100 All 100 users
Event All 100 users
At least one side effect7 100%
Lower libido after the cycle7 58%
Fluid retention during the cycle7 56%
Agitation during the cycle7 36%
Acne7 28%
Breast tissue growth (gynecomastia)7 19%

Four participants had a serious event: heart failure, pancreatitis, suicidal thoughts and a flare of ulcerative colitis. One year after the start the observed effects were back at baseline.7

Storage

Store at room temperature, protected from light - no fridge needed. Shake before use. Out of reach of children.

Related

Related compounds

Same receptors: all in the TPD lexicon.

Test Suspension
Test Base (Testosterone Suspension) - Research Substance Also testosterone without ester in water Testosterone Propionate Short ester, oil solution Testosterone Enanthate Long ester, basis of most trials Testosterone Cypionate Long ester Testosterone Undecanoate Very long ester Test Mix (high dose) Four esters in one oil

FAQ

Common questions about Test Suspension

Short answers, each backed by the sources below.

What is Test Suspension?

Testosterone without an ester, as fine crystals spread in water instead of dissolved in oil. The crystals settle in the vial, so it is shaken before every draw. According to the lexicon the suspension stings more at the injection site than oily esters and is only given intramuscularly.9

How long does one injection last?

Without an ester there is no depot to slow the compound down, according to the lexicon the half-life is in the range of hours. The sources checked here contain no measurements in humans of esterless testosterone given by injection. For comparison: even with the short propionate ester levels stayed above the lower normal limit for only one to two days after one injection, with enanthate for 14 days.5

Are there studies on the suspension?

As of 26 October 2026 ClinicalTrials.gov lists no trial with esterless testosterone as an aqueous suspension. The figures here therefore come from trials with testosterone esters and from observations in users.8

What do studies with testosterone show?

In the best-known trial 43 healthy men received testosterone enanthate or placebo for 10 weeks. Without training bench-press strength rose by 9 kg (placebo minus 1 kg), with training by 22 kg, plus 6.1 kg of fat-free mass. In a trial with five dose levels fat-free mass rose by 3.4, 5.2 and 7.9 kg in the three higher levels while HDL cholesterol fell with the level.13

Is testosterone approved?

Yes, as a compound. The ChEMBL database lists testosterone with phase 4 as the highest phase and first approval in 1972 as an agonist at the androgen receptor. Everything here is the state of research, not a recommendation.9

Which side effects do users report?

The HAARLEM study followed 100 men through a self-chosen cycle and one year. All reported at least one side effect, most often fluid retention (56 percent) and agitation (36 percent) during the cycle and lower libido afterwards (58 percent). Acne occurred in 28 percent and breast tissue growth in 19 percent. Four had a serious event. After one year the observed effects were back at baseline. In another trial haemoglobin and haematocrit rose linearly with the amount of testosterone, more in older men.7

What happens to the body's own hormone production?

Testosterone from outside suppresses the hormone axis. In the WHO study with weekly testosterone enanthate 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.6

Glossary

Terms explained briefly

Dotted words in the text open these explanations directly.

Androgen receptor
Protein inside the cell that testosterone and related compounds bind to. Genes are then read, for example for muscle building.
Aromatisation
The enzyme aromatase converts part of the testosterone into estradiol. This is where water retention and breast tissue effects come from.
Azoospermia
No sperm detectable in the ejaculate.
Ester
An attached fatty acid chain. It makes the compound 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, thigh or shoulder.
Placebo
Dummy preparation without active substance. Comparing against it shows what is due to the substance itself.
Supraphysiologic
Above the natural range the body makes on its own.
Suspension
Solid crystals spread in a liquid instead of dissolved. They settle and must be shaken up before every draw.

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 9 sourcesHide sources 7 Studies1 Trial registry1 Database checked 26 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 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. 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 26 Oct 2026 via doi.org, Crossref, PubMed
  4. Red blood cell production (haemoglobin, haematocrit) by testosterone dose

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

    DOI 10.1210/jc.2007-1692 PMID 18160461
    Checked 26 Oct 2026 via doi.org, Crossref, PubMed
  5. How long levels stay raised: propionate and enanthate compared

    Nieschlag et al., Hormone Research, 1976

    DOI 10.1159/000178721 PMID 1002121
    Checked 26 Oct 2026 via doi.org, Crossref (online 2008), 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 26 Oct 2026 via doi.org, Crossref, PubMed (Titel und Seiten, Datensatz ohne DOI)
  7. HAARLEM study: 100 users followed for 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 (Heft 2021, online 2020)

Trial registry

  1. Search for testosterone suspension on ClinicalTrials.gov

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

    Checked 26 Oct 2026 via ClinicalTrials.gov API v2

Database

  1. Testosterone in ChEMBL: mechanism and approval

    ChEMBL, EMBL-EBI (CHEMBL386630)

    Checked 26 Oct 2026 via ChEMBL

In the shop

Test Suspension in the catalog

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

To the product