¶ Description
Testosterone enanthate is a long-acting injectable form of testosterone designed for slow release into the bloodstream. After a deep intramuscular injection, it maintains stable testosterone levels for about 2 to 3 weeks. To sustain normal physiological levels during androgen replacement therapy, injections are typically administered every two weeks, though some physicians prefer weekly dosing for more consistent effects. Athletes often favor testosterone enanthate for its ability to significantly enhance muscle mass and strength.
¶ History:
Testosterone enanthate was first introduced to Western markets in the early 1950s. Developed to provide a longer-acting alternative to existing testosterone formulations, it was the first slow-releasing, oil-based injectable ester of testosterone. This innovation marked a significant shift in hormone replacement therapy, effectively replacing testosterone propionate and testosterone suspension for most therapeutic uses, as it required less frequent dosing.
The first commercial brand in the United States was Delatestryl®, launched by Squibb in 1953. Over the decades, Delatestryl® has changed ownership multiple times and is now marketed by Endo Pharmaceuticals. Outside the U.S., Testoviron® became the most prominent brand, initially produced by Schering AG and continuing in uninterrupted production for over 50 years, now under Bayer. Testoviron® is still widely prescribed across Europe, Latin America, and other regions.
Clinically, testosterone enanthate was a breakthrough for treating hypogonadism in adult males, a condition characterized by reduced testosterone levels, which can lead to a loss of libido, decreased muscle mass, and low energy. It was also used for other conditions like delayed puberty in adolescents and, occasionally, as a secondary treatment for inoperable breast cancer in women. During the 1960s and 1970s, it became a standard therapy in managing andropause (age-related testosterone decline), further solidifying its place in hormone replacement protocols.
In addition to medical use, testosterone enanthate gained popularity in the athletic community during the late 20th century for its ability to enhance muscle mass, strength, and endurance. Its prolonged action made it a preferred choice among athletes and bodybuilders, though this led to increased scrutiny and regulation due to concerns over performance-enhancing drug use.
The use of testosterone enanthate in bodybuilding began to surge in the 1960s and 1970s, coinciding with the rise of the modern fitness and bodybuilding culture. As athletes sought to enhance their physical performance and aesthetics, testosterone enanthate became a popular choice due to its ability to promote significant increases in muscle mass, strength, and overall physical endurance. Compared to earlier forms like testosterone propionate, its slower release and longer half-life made it more convenient, as athletes could maintain steady hormone levels with less frequent injections.
During the Golden Era of Bodybuilding in the 1970s, testosterone enanthate became a staple for many professional bodybuilders. Icons of the sport often used this drug to build the massive, defined physiques that became synonymous with competitive bodybuilding. Although direct documentation of steroid use was scarce during this period, the prevalence of anabolic steroids in bodybuilding circles was an open secret. Testosterone enanthate was favored not only for its effectiveness but also because it was widely available and relatively inexpensive compared to other anabolic steroids.
In the 1980s and 1990s, as the sport gained mainstream popularity, the use of testosterone enanthate and other anabolic steroids became more visible, leading to increased regulation and testing by athletic organizations. Despite the implementation of anti-doping measures and stricter controls, the drug continued to be used illicitly in bodybuilding circles, often combined with other anabolic steroids in a practice known as "stacking." This approach allowed athletes to maximize muscle gains while minimizing the side effects by adjusting the dosages and combining different compounds.
The increased attention on performance-enhancing drugs (PEDs) led to legislative actions, such as the Anabolic Steroid Control Act of 1990 in the United States, which classified testosterone and related substances as Schedule III controlled substances. This made it illegal to possess or distribute testosterone enanthate without a prescription, significantly impacting its accessibility for non-medical use. Despite these legal restrictions, the drug remains a popular choice among bodybuilders who use testosterone enanthate as part of Testosterone Replacement Therapy (TRT) or underground anabolic steroid cycles to maintain muscle size and strength. Today, it remains one of the most well-known and frequently used anabolic agents in the sport, with a legacy that spans several decades.
Testosterone enanthate has also been studied as a potential male contraceptive. Research in the 1990s showed that weekly injections of 200 mg could effectively lower sperm production within three months, maintaining suppression until treatment was discontinued. Despite promising results, the therapy has not been widely adopted in Western medicine due to the stigma surrounding anabolic steroids and the preference for other contraceptive methods.
With the growth of testosterone replacement therapy (TRT) in the 21st century, testosterone enanthate remains the most prescribed form of testosterone worldwide. Its longevity in the market is a testament to its effectiveness and practicality, even as newer therapies and formulations emerge.
¶ Quick Facts
Below are some quick facts about testosterone enanthate:
| Androgenic | 100 |
| Anabolic | 100 |
| Chemical Name | 17β-Hydroxyandrost-4-en-3-one 17-enanthate |
| Estrogenic Activity | Moderate |
| Progestational Activity | Low |
| Half-life | 8 days |
| Typically used for | Base, bulking, cutting |
¶ Side Effects
The side effects can be broken down into sub-categories:
¶ Androgenic
Testosterone is the primary male androgen, responsible for maintaining secondary male sexual characteristics such as muscle mass, body hair, and a deeper voice. Elevated levels of testosterone can lead to androgenic side effects, including oily skin, acne, and increased body or facial hair growth. Men who are genetically predisposed to androgenetic alopecia (male pattern baldness) may experience accelerated hair loss. Those concerned about this may prefer alternatives like nandrolone decanoate, which is less androgenic and has a milder effect on hair follicles.
For women, the use of anabolic/androgenic steroids, particularly potent androgens like testosterone, carries the risk of virilizing effects. These may include voice deepening, menstrual irregularities, changes in skin texture, facial hair growth, and clitoral enlargement. Due to these risks, women are generally advised to avoid or use caution with strong androgens.
The high androgenic activity of testosterone in androgen-responsive tissues (such as the skin, scalp, and prostate) is due to its conversion to dihydrotestosterone (DHT) via the 5-alpha reductase enzyme. Using 5-alpha reductase inhibitors like finasteride or dutasteride can reduce the conversion of testosterone to DHT, thereby lowering the likelihood of androgenic side effects in these tissues. However, it's important to note that anabolic and androgenic effects are both mediated through the androgen receptor, meaning complete separation of these effects is not achievable, even with full inhibition of DHT conversion.
While 5-alpha reductase inhibitors can mitigate some site-specific androgenic effects, they do not eliminate the general androgenic activity of testosterone, and users may still experience other side effects, such as increased body hair or acne. Therefore, understanding the balance between anabolic and androgenic properties is crucial when considering testosterone use, especially at doses above therapeutic levels.
¶ Cardiovascular
Anabolic and androgenic steroids can have harmful effects on serum cholesterol levels. They often decrease HDL (high-density lipoprotein), known as the "good" cholesterol, while increasing LDL (low-density lipoprotein), the "bad" cholesterol. This alteration in the HDL to LDL ratio can shift the balance in a way that heightens the risk of arteriosclerosis. The degree to which these steroids impact serum lipids depends on factors such as the dosage, the method of administration (oral versus injectable), the specific type of steroid (whether it is aromatizable or not), and its resistance to liver metabolism. Furthermore, anabolic and androgenic steroids may negatively influence blood pressure and triglyceride levels, impair endothelial relaxation, and promote left ventricular hypertrophy. These changes collectively can elevate the risk of cardiovascular diseases and myocardial infarction.
Testosterone typically has a much less pronounced impact on cardiovascular risk factors compared to synthetic steroids. This is partly because it is more readily metabolized by the liver, which reduces its effect on the liver's management of cholesterol. Additionally, the conversion of testosterone to estradiol (aromatization) helps lessen the negative effects of androgens on serum lipid profiles.
Due to the positive effects of estrogen on serum lipid profiles, medications such as tamoxifen citrate or clomiphene citrate are often preferred over aromatase inhibitors for those concerned about cardiovascular health. These drugs offer a partial estrogenic effect in the liver, which can help improve lipid profiles and offset some of the negative impacts of androgens. When using testosterone doses of 600 mg or less per week, the changes in lipid profiles are typically noticeable but not severe, potentially making the use of an anti-estrogen for cardioprotective purposes unnecessary.
To mitigate cardiovascular strain, it's advisable to maintain a regular cardiovascular exercise routine and consistently reduce the intake of saturated fats, cholesterol, and simple carbohydrates during periods of active anabolic-androgenic steroid (AAS) use. Supplementing your diet with fish oil—4 grams daily—and incorporating a natural cholesterol-lowering and antioxidant supplement like Lipid Stabil, or a similar product with comparable ingredients, is also recommended.
¶ Estrogenic
Testosterone enanthate can be converted into estradiol (estrogen) in the body through a process known as aromatization, facilitated by the aromatase enzyme. This increase in estrogen levels may lead to side effects such as water retention, fat gain, and gynecomastia (development of breast tissue in males). Due to its moderate tendency to convert to estrogen, testosterone is considered a moderately estrogenic steroid.
To mitigate these effects, anti-estrogens like clomiphene citrate (Clomid®) or tamoxifen citrate (Nolvadex®) can be used. These medications work by blocking estrogen receptors, thereby reducing the risk of estrogen-related side effects. Alternatively, one can use aromatase inhibitors (AIs) such as anastrozole (Arimidex®), which prevent the conversion of testosterone to estrogen, offering more effective control. However, aromatase inhibitors tend to be more expensive and can negatively affect blood lipid profiles, potentially increasing the risk of cardiovascular issues.
The occurrence of estrogenic side effects is dose-dependent, meaning higher doses of testosterone (beyond therapeutic levels) increase the likelihood of needing anti-estrogen or AI support. At higher doses, users often experience water retention and a loss of muscle definition, making testosterone enanthate less suitable for cutting or dieting phases of training. However, its moderate estrogenicity can be beneficial during bulking phases, where increased water retention contributes to muscle size and strength gains and helps create a more anabolic environment.
Studies have shown that using 300 mg of testosterone enanthate per week for 20 weeks without an aromatase inhibitor resulted in only a 13% decrease in HDL cholesterol levels, while increasing the dosage to 600 mg per week led to a 21% reduction. This was demonstrated in the study "Testosterone dose-response relationships in healthy young men" by Bhasin, Woodhouse, and colleagues, published in the American Journal of Physiology—Endocrinology and Metabolism (2001). The negative impact of aromatase inhibition should be taken into consideration before such a drug is added to testosterone therapy.
¶ Hepatoxicity
Testosterone enanthate is generally not associated with liver toxicity, and the likelihood of hepatotoxic effects is low. In a study published by Johnsen et al. in Clinical Pharmacology & Therapeutics (1976), male subjects were administered high doses of oral testosterone—400 mg per day, totaling 2,800 mg per week—to assess potential liver impact. The oral route was chosen to achieve higher peak concentrations in liver tissue compared to intramuscular injections. Over a 20-day period of daily administration, the participants exhibited no significant changes in liver enzyme levels, including serum albumin, bilirubin, alanine aminotransferase (ALT), and alkaline phosphatases. This suggests that even at high doses, testosterone enanthate does not significantly affect liver function (Johnsen et al., 1976).
¶ Testosterone Suppression
All anabolic-androgenic steroids, when taken in doses sufficient to promote muscle growth, are expected to suppress the body's natural production of testosterone. Testosterone, being the primary male androgen, provides strong negative feedback on endogenous testosterone synthesis. Testosterone-based medications will similarly have a significant impact on the hypothalamic regulation of natural steroid hormones. Without the use of testosterone-stimulating substances, natural testosterone levels typically return to normal within one to four months after discontinuing the drug. It's important to note that prolonged steroid use can lead to secondary hypogonadotropic hypogonadism, which may require medical intervention.
As is common with all anabolic-androgenic steroids, it's unlikely that all the gained body weight will be maintained after completing a cycle. This is especially true when stopping a potent (aromatizing) androgen like testosterone, as much of the weight gain is often due to water retention, which is quickly lost after discontinuation. An imbalance between anabolic and catabolic hormones during the post-cycle recovery period can further create an environment unfavorable for maintaining muscle mass. Therefore, appropriate ancillary drug therapy is usually recommended to help restore hormonal balance more rapidly, ultimately aiding in the retention of muscle tissue.
¶ Dosing
To treat androgen deficiency, medical guidelines suggest administering testosterone enanthate at doses between 50 and 400 mg every two to four weeks. Despite its long-acting nature, those using testosterone enanthate for muscle-building purposes often inject it on a weekly basis. For physique or performance enhancement, typical dosages range from 200 to 600 mg per week in cycles lasting 6 to 12 weeks. This dosage is generally sufficient for most users to achieve significant gains in muscle size and strength.
Testosterone is commonly incorporated into bulking phases of training, where additional water retention is less concerning because the focus is on overall mass rather than muscle definition. Some users also include testosterone in cutting cycles but usually at lower doses (100-200 mg per week) and/or with an aromatase inhibitor to manage estrogen levels. Testosterone enanthate is a highly effective anabolic agent and is often used alone with great success. However, some individuals choose to stack it with other anabolic-androgenic steroids for enhanced effects. In such cases, adding 200-400 mg per week of compounds like boldenone undecylenate, methenolone enanthate, or nandrolone decanoate can produce substantial results without significant liver toxicity. Testosterone is extremely versatile and can be combined with various other steroids to tailor specific outcomes.
In clinical settings, testosterone enanthate is seldom prescribed to women. When it is used, it's typically as a secondary treatment for inoperable breast cancer when other therapies have failed and suppression of ovarian function is required. For women seeking physique or performance enhancement, testosterone enanthate is not recommended due to its strong androgenic effects, the high risk of virilizing side effects, and its slow-acting characteristics that make blood levels difficult to control.