Injectable AAS / IM, SubQ / 100-500mg per week
Testosterone Enanthate
Testosterone enanthate came out of the early-1950s search for an injectable androgen that would last longer than a couple of days, and it then held the position of the world's standard testosterone preparation for roughly fifty years. Most of the classic clinical trials of testosterone dosing were run with it, which is why its evidence base is deeper than that of any other ester.
In plain words
Testosterone enanthate is plain testosterone with a straight seven-carbon tail attached, which makes it oil-soluble so that an injection sits as a depot in the muscle and leaks out over days; enzymes in the blood clip the tail off, and what acts on the body is ordinary testosterone. It reached the market in the mid-1950s and was the world's standard testosterone preparation for about fifty years, which is why most of the classic clinical numbers people quote about testosterone were actually measured on this ester. Its evidence base is correspondingly deep: randomized trials show it increases muscle size and strength and that the effect grows with the dose, and a ten-center clinical study found weekly injections suppress sperm production strongly enough to be tested as a male contraceptive. It is an approved prescription drug, including a weekly under-the-skin autoinjector approved in the United States in 2018 whose label reports an average rise in blood pressure after twelve weeks of treatment; testosterone and its esters have been Schedule III controlled substances there since 1990. Compared head to head with its near-twin cypionate in a single 1980 study, the two gave effectively the same hormone curves, though that report is a short note whose details are not on the accessible record.
At a glance
| Half-life | 7.19 days |
|---|---|
| Tmax | 1.39 days |
| Route(s) | IM, SubQ |
| Published dosing range | 100-500mg per week |
Reference data from the DosePlot canon -- not a protocol recommendation.
Serum curve
Single 300 mg dose by IM, rendered from the same engine that powers the interactive chart. Relative levels, not lab values.
What does the evidence show?
Two things are labeled separately here because they answer different questions. The tier is how a study was built. The distance chips are whether that study touched this molecule, by this route, in a population resembling the reader. A randomized trial of a different molecule keeps its tier and still says nothing about this compound.
| Finding | Tier | Distance from use | Study |
|---|---|---|---|
| In 43 healthy men randomly assigned to 600 mg of testosterone enanthate weekly or placebo for 10 weeks, the men given testosterone gained more fat-free mass, muscle size and bench-press and squat strength, both with and without a supervised weight-training program. | rct | not recorded | Bhasin S, Storer TW, Berman N, et al. The effects of supraphysiologic doses of testosterone on muscle size and strength in normal men.New England Journal of Medicine 335(1):1-7, 1996 |
| In 61 healthy young men whose own testosterone production was suppressed with a monthly GnRH agonist, weekly testosterone enanthate at 25, 50, 125, 300 or 600 mg for 20 weeks raised fat-free mass only at the three higher doses (changes of about 3.4, 5.2 and 7.9 kg at 125, 300 and 600 mg). Leg-press strength, thigh and quadriceps muscle volume, hemoglobin and IGF-1 rose with testosterone concentration, while fat mass and HDL cholesterol fell. Because endogenous production was suppressed, the listed doses are total replacement, not doses added on top of a man's own output. | rct | not recorded | Bhasin S, Woodhouse L, Casaburi R, et al. Testosterone dose-response relationships in healthy young men.American Journal of Physiology Endocrinology and Metabolism 281(6):E1172-E1181, 2001 |
| Across four regimens (100 mg weekly, 200 mg every 2 weeks, 300 mg every 3 weeks, 400 mg every 4 weeks) in hypogonadal men, serum testosterone fluctuated largely within the normal range on all four, but the average level between doses was highest on the weekly schedule and lowest on the four-week schedule, and only the four-week schedule failed to bring an elevated LH back to normal. | clinical | not recorded | Snyder PJ, Lawrence DA. Treatment of male hypogonadism with testosterone enanthate.Journal of Clinical Endocrinology and Metabolism 51(6):1335-1339, 1980 |
| A single 200 mg intramuscular injection kept serum testosterone in the normal male range through day 11 in hypogonadal men; a 100 mg injection kept it there through day 7. | clinical | not recorded | Sokol RZ, Palacios A, Campfield LA, Saul C, Swerdloff RS. Comparison of the kinetics of injectable testosterone in eugonadal and hypogonadal men.Fertility and Sterility 37(3):425-430, 1982 |
| Testosterone enanthate suppresses sperm production. In a ten-center study of 271 fertile men given 200 mg weekly by intramuscular injection, 65 percent reached azoospermia within six months (mean time 120 days), and among those men there was one pregnancy across 1486 months of exposure with no other contraception. | clinical | not recorded | World Health Organization Task Force on Methods for the Regulation of Male Fertility. Contraceptive efficacy of testosterone-induced azoospermia in normal men.Lancet 336(8721):955-959, 1990 |
| Given subcutaneously once a week by autoinjector at 50 or 100 mg, testosterone enanthate restored serum testosterone to the normal range in hypogonadal men, with steady, dose-proportional exposure. | clinical | not recorded | Kaminetsky J, Jaffe JS, Swerdloff RS. Pharmacokinetic profile of subcutaneous testosterone enanthate delivered via a novel, prefilled single-use autoinjector: a phase II study.Sexual Medicine 3(4):269-279, 2015 |
| Compared head to head in a single 1980 study, testosterone enanthate and testosterone cypionate produced effectively the same serum testosterone, dihydrotestosterone, LH and FSH curves. The report is a three-page note with no abstract on record, so the number of men, the doses and the oil used are not stated in the abstract or in freely accessible full text; take it as a direct comparison rather than a formal equivalence trial. | clinical | not recorded | Schulte-Beerbuhl M, Nieschlag E. Comparison of testosterone, dihydrotestosterone, luteinizing hormone, and follicle-stimulating hormone in serum after injection of testosterone enanthate or testosterone cypionate.Fertility and Sterility 33(2):201-203, 1980 |
| People who switch between enanthate and cypionate at the same weekly milligram total usually report no difference they can detect. Where a difference is reported it is most often injection-site soreness, which community reports tend to attribute to the carrier oil and the injected volume rather than to the ester. | anecdotal | not recorded | community reports aggregated from reddit, MESO-Rx, and similar forumsno study |
How did it get here?
- preclinical1935
- Testosterone is isolated by Ernst Laqueur's group in Amsterdam, and in the same year it is chemically synthesized, independently, by Butenandt and by Ruzicka. Unmodified testosterone injected into muscle is cleared within hours, so it is close to useless as a depot drug.
- preclinical1952
- Junkmann, working at Schering, publishes on androgens with protracted action. The principle is to hang a fatty acid on the 17-beta hydroxyl so the molecule dissolves in oil and leaves the injection site slowly. Enanthate comes out of this line of work; other long-chain esters, cypionate among them, were developed at other companies.
- clinical-adoptionmid-1950s
- Testosterone enanthate reaches the market (Delatestryl in the United States) and displaces the short-acting propionate. It remains the major testosterone preparation worldwide for about half a century.
- clinical-adoption1990
- The World Health Organization runs its multicenter male contraception trial on 200 mg of testosterone enanthate weekly. Among the men who reached azoospermia there is one pregnancy across 1486 months of exposure. The ester and the dose are the same ones people were already using for other purposes.
- grey-market1990-2010
- The Anabolic Steroid Control Act of 1990 places testosterone and any ester of it in United States Schedule III. Licensed supply continues: the scheduling adds prescribing and recordkeeping controls rather than taking the drug off pharmacy shelves. Enanthate also keeps a second life outside clinics, where the ester chemistry is old and undemanding, so what actually varies in unregulated product is concentration accuracy, sterility and whether any batch testing happened at all.
- clinical-adoption2018
- A weekly subcutaneous autoinjector (Xyosted, 50, 75 or 100 mg in sesame oil, preservative-free, single-dose) is approved in the United States, the first self-administered subcutaneous testosterone product. It carried a boxed warning about blood-pressure increases. The label's own change log records that boxed warning as removed in March 2025; blood-pressure increases remain in the warnings and precautions section, where the label reports an average rise of 3.9 mm Hg systolic and 1.5 mm Hg diastolic after 12 weeks of treatment.
How is it made?
Production happens in three stages.
1. Making the testosterone. The starting material is plant sterol, not animal tissue: phytosterols from soy, or diosgenin from wild yam. Fermentation and chemistry cut the plant side chain away to leave the bare four-ring steroid core, which is then carried through a short, standard sequence to testosterone. Every testosterone product begins from this same commodity intermediate.
2. Attaching the enanthate ester. Testosterone is reacted with heptanoic acid, whose older name is enanthic acid, which hangs a straight seven-carbon tail off the 17-beta position. The label name for the finished molecule is androst-4-en-3-one, 17-[(1-oxoheptyl)-oxy]-. The tail adds no activity of its own. It makes the molecule oil-soluble and slow: injected as an oil depot, the ester leaves the muscle over days, and esterases in blood clip the tail off to release plain testosterone. Testosterone is 72 percent of the finished ester by weight, so a 200 mg dose carries about 144 mg of testosterone.
3. Filling the vial. The ester is a low-melting waxy solid and dissolves readily in oil. United States multi-dose vials are sesame oil at 200 mg per mL with chlorobutanol as the preservative; the subcutaneous autoinjector uses sesame oil with no preservative. The solution is sterile-filtered and filled. Under GMP rules each batch is assayed for identity, potency, sterility and endotoxins. The chemistry is seventy years old and cheap. Sterile filling and batch testing are the expensive parts, and they are exactly what varies outside regulated manufacturing.
Worth knowing
Testosterone enanthate melts at about 36 to 37.5 C, essentially body temperature. Its near-twin cypionate melts at 98 to 104 C. That is the ordinary consequence of a flexible straight chain packing badly into a crystal lattice where a rigid ring packs well. Two molecules that behave the same in blood behave nothing alike as raw solids.
National Center for Biotechnology Information. PubChem compound records for testosterone enanthate (CID 9416) and testosterone cypionate (CID 441404), experimental properties.PubChem compound summary, melting points as deposited by the Human Metabolome Database and DrugBank, retrieved 2026-08-27
Because enanthate was the standard preparation for about fifty years, it is the ester underneath most of the numbers people quote about testosterone. The 1996 supraphysiologic-dose trial, the 2001 dose-response study and the WHO male contraception trial all used it. When a figure like 600 mg per week is cited, that figure was measured on enanthate.
Nieschlag E, Nieschlag S. Testosterone deficiency: a historical perspective.Asian Journal of Andrology 16(2):161-168, 2014
Written and reviewed by Evan Marlow, developer of DosePlot · Updated 2026-08-27
Not medical advice. DosePlot is an informational tool, not a healthcare provider, and using it creates no provider-patient relationship. Do not start, stop, or change any protocol without the approval of a licensed healthcare professional.
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