Testosterone phenylpropionate (often shortened to TPP) is testosterone with a 3-phenylpropionate ester attached. Like other testosterone esters, it is injected into muscle in oil, and the ester is cut off in the body to release ordinary testosterone. It was reported as “a new androgen” in 1953 (Dekanski and Chapman, Br J Pharmacol 1953).
Today it is not sold on its own as a licensed human medicine in the US, UK or Poland, as far as their drug registries show. Its main medical role is as one of four esters in blends such as Sustanon 250 and Omnadren 250, which each contain 60 mg per mL. No dedicated human pharmacokinetic study or controlled clinical trial of the single ester could be found, so most of what is known comes from those blends.
This page summarizes what the product labels, drug registries and published studies report. It is for education only and is not medical advice.
| Property | Detail |
|---|---|
| Drug class | Androgen; testosterone ester (anabolic-androgenic steroid) |
| Chemistry | Testosterone 17β-(3-phenylpropionate); C₂₈H₃₆O₃, 420.6 g/mol |
| Testosterone content | ≈69% of the ester’s weight (60 mg ester ≈ 41 mg testosterone) |
| Licensed products containing it | Sustanon 250 (UK) and Omnadren 250 (Poland): 60 mg per mL, mixed with three other esters |
| Route | Deep intramuscular injection (as part of a blend) |
| Labeled dose | Only as part of Sustanon 250: usually 1 mL every 3 weeks, which contains 60 mg of TPP |
| Half-life | No dedicated human study found; ≈2.5 days quoted in a secondary source |
| US status | No FDA-approved product; testosterone and its esters are Schedule III |
| WADA status | Testosterone is listed under S1.1 anabolic agents, prohibited at all times |
What it is
TPP is the 17β-ester of testosterone with 3-phenylpropionic acid. PubChem lists the formula as C₂₈H₃₆O₃ and the molecular weight as 420.6 g/mol, against 288.4 g/mol for testosterone itself (PubChem). The ester therefore makes up about 31% of the dose’s weight.
The ester has no hormonal activity of its own. The Sustanon label states that its esters are hydrolyzed to the natural hormone testosterone as soon as they enter the general circulation (UK SmPC). Once released, testosterone acts on the androgen receptor and is converted in part to dihydrotestosterone (DHT) and estradiol, exactly as with testosterone cypionate or enanthate.
Unlike most testosterone esters, which have straight or branched carbon chains, the phenylpropionate side chain ends in a benzene ring. The same ester is used on nandrolone, as nandrolone phenylpropionate.
The table compares TPP with other testosterone esters, using PubChem values. XLogP is a computed estimate of fat solubility (higher means more fat-soluble), not a measured release rate.
| Ester | Molecular weight | Share that is testosterone | Computed XLogP |
|---|---|---|---|
| Testosterone (no ester) | 288.4 g/mol | 100% | 3.3 |
| Propionate | 344.5 g/mol | ≈84% | 4.4 |
| Phenylpropionate | 420.6 g/mol | ≈69% | 5.8 |
| Isocaproate | 386.6 g/mol | ≈75% | 5.5 |
| Enanthate | 400.6 g/mol | ≈72% | 6.3 |
| Cypionate | 412.6 g/mol | ≈70% | 6.4 |
| Decanoate | 442.7 g/mol | ≈65% | 8.0 |
Source: PubChem compound summaries. Testosterone share is testosterone’s molecular weight divided by the ester’s.
A 2022 crystallography study solved the crystal structure of TPP and measured how well several short testosterone esters dissolve in oil mixtures (Turza et al., Materials 2022). Phenylpropionate dissolved about as well as propionate, even though it has six more carbon atoms. The authors concluded that the phenyl ring does not add oil solubility the way a longer carbon chain does.
Pharmacokinetics
What is known about the single ester
We found no published human study that gave TPP on its own and measured its half-life. The figure most often quoted comes from secondary sources. The 2022 crystallography paper lists approximate half-lives of about 1 day for propionate, 2.5 days for phenylpropionate and 3.1 days for isocaproate (Turza et al., Materials 2022). It cites a Sustanon blood study for these values, but that study’s abstract reports detection windows, not half-lives (Forsdahl et al., Drug Test Anal 2015). Treat the 2.5-day figure as approximate.
Inside a blend
Most human data come from Sustanon 250, which contains 30 mg propionate, 60 mg phenylpropionate, 60 mg isocaproate and 100 mg decanoate per mL (UK SmPC). The label reports these values for a single dose of the whole blend:
| Measure | Value |
|---|---|
| Peak total testosterone | ≈70 nmol/L (≈2,000 ng/dL) |
| Time to peak | ≈24–48 h |
| Return to the lower limit of the male normal range | ≈21 days |
These numbers describe the combined release of all four esters, not TPP alone.
The intact esters can also be measured in blood. In a study of six volunteers given Sustanon or testosterone undecanoate, every ester in the products was detectable after the injection, and the detection time depended on which ester was given (Forsdahl et al., Drug Test Anal 2015). Summarizing that study, a later trial noted that the individual Sustanon esters peaked in blood within 24–72 hours, with timing that varied between people and with the length of the ester side chain (Solheim et al., Front Physiol 2020).
Evidence from the nandrolone version
The closest controlled comparison uses nandrolone rather than testosterone. In a randomized study of 23 healthy men given 100 mg of nandrolone ester, the phenylpropionate ester produced higher and earlier nandrolone peaks than the decanoate ester (Minto et al., J Pharmacol Exp Ther 1997). It also suppressed the men’s own testosterone most rapidly but most briefly. This shows how the phenylpropionate ester behaves compared with a long ester, but the numbers cannot be transferred directly to testosterone.
Approved medical use
TPP is licensed only as part of a mixed-ester product in the registries we checked:
- Sustanon 250 (UK). Licensed since February 1973 for testosterone replacement in men with confirmed hypogonadism and as supportive therapy for transgender men. The usual adult dose is 1 mL every 3 weeks, so each dose contains 60 mg of TPP within a 176 mg total testosterone dose (UK SmPC).
- Omnadren 250 (Poland). The Polish medicines register lists it with the same four esters in the same amounts: 30 mg + 60 mg + 60 mg + 100 mg per mL (Polish medicinal products register).
The full labeled uses, dosing and monitoring for the blend are covered on the Sustanon 250 page.
In the US, the FDA’s Drugs@FDA database returns no product containing testosterone phenylpropionate (openFDA Drugs@FDA).
What the research shows
Studies of TPP alone
TPP was studied as a new single-ester androgen in the 1950s (Dekanski and Chapman, Br J Pharmacol 1953; Klotz and Avril, Therapie 1955). Those early reports are not available in full text online, so we do not report their results here. We found no modern randomized controlled trial of TPP given on its own.
Delayed puberty in boys
In an uncontrolled study, 13 boys with constitutional delay of puberty received a combination of three esters: testosterone propionate, phenylpropionate and isocaproate (Büyükgebiz, Horm Res 1995). They were given 200 mg intramuscularly four times, 3 weeks apart, and followed for 2 years.
| Measure | Before treatment | After 2-year follow-up |
|---|---|---|
| Growth rate | 4.5 cm/year | 8.4 cm/year |
| Height for bone age (SD score) | −1.1 | −1.3 (no significant change) |
| Predicted adult height | 173.5 cm | 173.3 cm |
All 13 boys entered puberty after the last dose. Predicted adult height did not fall, which suggests the course did not shorten final height. With no control group and only 13 boys, the results are preliminary.
Studies using the four-ester blends
Several small trials have used Sustanon 250 as their testosterone source; they are summarized on the Sustanon 250 page. Their results reflect the blend’s total testosterone dose, and none separates out the effect of the TPP component.
Side effects and risks
There is no separate safety data for TPP. Its effects are those of testosterone, and the risks below come from the Sustanon 250 label and studies of TPP-containing products.
Labeled adverse reactions
The Sustanon label lists reactions associated with androgen therapy in general (UK SmPC):
- Common (1 in 100 to 1 in 10): weight gain; raised hematocrit (the share of blood made up of red cells), hemoglobin and red cell count.
- Rare: pulmonary oil microembolism, where oil reaches the lungs during or right after injection and causes cough, shortness of breath or chest pain.
- Frequency not known: fluid retention, high blood pressure, mood changes, acne, gynecomastia, low sperm count, priapism, prostate growth, raised PSA, abnormal liver tests and lipid changes.
The label notes that side effects cannot be reversed quickly by stopping, because the oil depot keeps releasing hormone. In women, it warns of virilization, including voice changes that may be permanent.
Fertility and natural testosterone
Outside testosterone suppresses the pituitary signals that drive the testes. The label warns that androgens can impair male fertility by suppressing sperm production. In healthy young men, LH (the pituitary hormone that stimulates testosterone production) fell from 3.8 to 1.6 IU/L within 24 hours of a single Sustanon 250 injection (Solheim et al., Front Physiol 2020).
Breast cancer report
A Polish case series followed 45 men with hypergonadotropic hypogonadism who received Omnadren 250 every 3–4 weeks for 5–26 years (Medras et al., Breast Cancer Res Treat 2006). Two of them developed breast cancer, after 11 and 15 years of treatment. The authors suggested a possible link with long-term androgen replacement. A small series without a comparison group cannot show cause, but the label does contraindicate testosterone in known or suspected breast cancer.
Who should not use it
The Sustanon label contraindicates the product in:
- pregnancy and breastfeeding;
- known or suspected prostate or breast cancer;
- allergy to any ingredient, including the peanut (arachis) oil carrier, and therefore in people allergic to peanuts or soya.
Legal status and use outside medicine
- US. No FDA-approved product contains TPP. Testosterone, “including its salts, esters and ethers,” is a Schedule III anabolic steroid under federal law (21 CFR 1308.13).
- Sport. Testosterone is listed under S1.1 anabolic androgenic steroids, which are prohibited in and out of competition (WADA 2026 Prohibited List). Finding an intact testosterone ester in blood proves the testosterone came from outside the body (Forsdahl et al., Drug Test Anal 2015).
- Non-medical use. In a 2025 Swedish study of 10 self-reported anabolic steroid users, TPP was among the testosterone esters detected in dried blood spot samples (Suominen et al., Drug Test Anal 2025). Product sold outside a pharmacy is not regulated for dose, sterility or identity.
Key takeaways
- Testosterone with a short-to-medium ester. TPP releases ordinary testosterone. About 69% of each milligram is testosterone.
- Mostly a blend component. In the registries checked, it is licensed only as one of four esters in Sustanon 250 and Omnadren 250, at 60 mg per mL. No FDA-approved product contains it.
- Half-life is poorly documented. No dedicated human pharmacokinetic study was found. The ≈2.5-day figure comes from a secondary source.
- Little direct clinical evidence. No modern controlled trial of TPP alone exists. Human data come from blends, where its effect cannot be separated from the other esters.
- Testosterone’s risks apply. Raised hematocrit, suppressed LH and sperm production, and the other labeled androgen effects are expected.
Sources
- Aspen Pharma Trading Limited. Sustanon 250, 250mg/ml solution for injection: Summary of Product Characteristics. PL 39699/0059; revised December 2025. emc.
- Polish Office for Registration of Medicinal Products. Register of medicinal products: Omnadren 250 (testosterone propionate, phenylpropionate, isocaproate and decanoate). Rejestr Produktów Leczniczych.
- National Center for Biotechnology Information. PubChem compound summaries: testosterone phenylpropionate (CID 14743), testosterone (CID 6013), testosterone propionate (CID 5995), testosterone isocaproate (CID 231084), testosterone enanthate (CID 9416), testosterone cypionate (CID 441404), testosterone decanoate (CID 155143). PubChem.
- Dekanski J, Chapman RN. Testosterone phenyl propionate (TPP): biological trials with a new androgen. Br J Pharmacol Chemother. 1953;8(3):271–277. PubMed.
- Klotz HP, Avril Y. New androgen for retarded action; testosterone phenylpropionate [in French]. Therapie. 1955;10(4):588–590. PubMed.
- Turza A, Popescu V, Mare L, Borodi G. Structural aspects and intermolecular energy for some short testosterone esters. Materials (Basel). 2022;15(20):7245. PubMed.
- Forsdahl G, Erceg D, Geisendorfer T, et al. Detection of testosterone esters in blood. Drug Test Anal. 2015;7(11-12):983–989. PubMed.
- Solheim SA, Mørkeberg J, Juul A, et al. An intramuscular injection of mixed testosterone esters does not acutely enhance strength and power in recreationally active young men. Front Physiol. 2020;11:563620. PubMed.
- Minto CF, Howe C, Wishart S, Conway AJ, Handelsman DJ. Pharmacokinetics and pharmacodynamics of nandrolone esters in oil vehicle: effects of ester, injection site and injection volume. J Pharmacol Exp Ther. 1997;281(1):93–102. PubMed.
- Büyükgebiz A. Treatment of constitutional delayed puberty with a combination of testosterone esters. Horm Res. 1995;44(Suppl 3):32–34. PubMed.
- Medras M, Filus A, Jozkow P, Winowski J, Sicinska-Werner T. Breast cancer and long-term hormonal treatment of male hypogonadism. Breast Cancer Res Treat. 2006;96(3):263–265. PubMed.
- Suominen T, von Walden J, Harju L, et al. Detection of anabolic androgenic steroids and steroid esters: comparing dried blood spots collection devices and urine samples. Drug Test Anal. 2025;17(12):2374–2383. PubMed.
- US Food and Drug Administration. Drugs@FDA dataset, queried via openFDA for the active ingredient testosterone phenylpropionate (no matches). openFDA.
- Drug Enforcement Administration. Schedules of controlled substances: Schedule III, paragraph (f), anabolic steroids. 21 CFR 1308.13. eCFR.
- World Anti-Doping Agency. The 2026 Prohibited List: International Standard. In effect January 1, 2026. WADA 2026 Prohibited List.