Trenbolone has a reputation as one of the most powerful and at the same time the most "heavy" anabolic steroids. This reputation is well-founded: the high affinity for androgen receptors, progestogenic activity and long-lasting action of the long ester create a wide range of side effects. The editors systematized the known risks by organ system and explained which of them were confirmed by research and which were only observed.
Where does the side effect profile come from
Trenbolone is a synthetic 19-norsteroid, which, according to a study by Bauer et al. (2000), binds to the human androgen receptor more strongly than testosterone and at the same time has a pronounced affinity for the progesterone receptor. It does not aromatize into estradiol. Each of these properties forms a separate group of potential side effects.
It is important to understand that trenbolone has never been systematically studied in high-dose randomized clinical trials in humans. Therefore, our knowledge of its side effects comes from three sources: animal experiments, general data on supraphysiological doses of anabolic steroids, and clinical case reports in humans who used trenbolone alone, often in combination with other substances.
The last circumstance significantly complicates the assessment. In real life, trenbolone is almost always combined with testosterone and other drugs, so it is impossible to isolate the "contribution" of trenbolone itself. However, a review by the Endocrine Society (Pope et al., 2014) and a large number of cohort studies allow us to describe the overall picture of the risks of supraphysiological androgen loading, to which trenbolone makes a notable contribution.
Long-lasting ester enanthate adds another feature: when unwanted reactions occur, the substance cannot be quickly "removed". Depot continues to release trenbolone over a long period of time, so side effects can persist for weeks after the last injection.
Heart, vessels and blood
Cardiovascular risks are considered the most dangerous consequences of supraphysiological doses of androgens. A study by Baggish et al (2017) published in the journal Circulation found that male long-term users of anabolic steroids had lower left ventricular systolic function and larger coronary plaque volume than strength athletes who did not use them.
For 19-norsteroids and trenbolone, a pronounced decrease in the level of high-density lipoproteins (HDL) is especially characteristic. The combination of low HDL, elevated LDL, and hypertension accelerates atherosclerosis. These changes have no symptoms, and a person may not suspect them for years without tests.
On the blood side, androgens stimulate the formation of erythrocytes, which increases hematocrit and blood viscosity. This increases the load on the heart and, according to observations, the risk of thrombosis. Separately described cases of myocardial infarction and stroke in young people who used anabolic steroids, although it is difficult to prove a causal relationship in an individual case.
| System | Possible effects | Level of evidence |
|---|---|---|
| Lipids | Sharp decrease in HDL, increase in LDL | Well documented for androgens in general |
| Blood pressure | Increased blood pressure | Cohort studies |
| Myocardium | Hypertrophy, decrease in contractility | Cross-sectional studies (Baggish 2017) |
| Blood | Erythrocytosis, increased hematocrit | Well documented |
| Hormones | LH/FSH suppression, infertility | Well documented |
| Kidneys | Proteinuria, focal segmental glomerulosclerosis | Series of cases |
| Mental health | Irritability, aggression, insomnia, depression after withdrawal | Observation and survey |
About the cardiovascular system, the editors have prepared a separate material, which analyzes lipids, blood pressure, and hematocrit in more detail. Here we emphasize the main point: cardiovascular changes accumulate and may persist after cessation of use.
Hormonal and reproductive system
As a powerful agonist of androgen receptors with progestogenic activity, trenbolone effectively suppresses the production of gonadotropins — luteinizing (LH) and follicle-stimulating (FSH) hormones. The result is a drop in own testosterone, a decrease in the volume of the testicles and a violation of spermatogenesis up to azoospermia.
Since trenbolone is not aromatized, and its own testosterone is suppressed, the level of estradiol with "isolated" use of trenbolone can decrease. Low estradiol in men is associated with decreased libido, deterioration of bone health and lipid profile. At the same time, in combination with testosterone, estrogenic effects, on the contrary, can be pronounced.
The progestogenic activity of trenbolone can theoretically contribute to the development of gynecomastia in combination with estrogens. There is little clinical evidence in humans, but the mechanism is biologically plausible, and gynecomastia as a complication of supraphysiological androgen load has been widely described. Read more about this in a separate editorial article.
Restoration of the hormonal axis after long-term use of anabolic steroids can take months, and some men develop persistent hypogonadism. A review by Rahnema et al (2014) describes this condition as one of the most common causes of hypogonadism in young men.
Psyche, sleep and breathing
Trenbolone users often report irritability, anxiety, aggression, sleep disturbances, and night sweats. These reports are mostly in the nature of surveys and forum reports, but they are consistent with data on the psychiatric effects of anabolic steroids in general as described by Kanayama et al (2008).
Depressive states after cessation of use deserve special attention. A sharp drop in the androgenic background against the background of a suppressed own axis can cause apathy, low mood and even suicidal thoughts. In this case, timely medical and psychological help is needed, and not independent experiments with drugs.
- irritability and tendency to conflicts;
- insomnia, restless sleep, night sweats;
- anxiety and panic reactions;
- depressed mood, especially after withdrawal;
- cough and a feeling of lack of air immediately after the injection.
The last point — the so-called "cough after injection" — is usually associated with the entry of a small amount of oil solution into the bloodstream and microembolism of the pulmonary vessels. This mechanism is described for oily injectable preparations of testosterone. Any attack of coughing with shortness of breath or chest pain requires seeking medical attention.
Animal studies also report increased aggressiveness in rodents under the influence of trenbolone, but these results should be extrapolated to humans with caution. Human response depends on individual susceptibility, dose, combination with other substances, and social context.
Kidneys, liver, skin
Nephrologists described the development of focal segmental glomerulosclerosis in bodybuilders who used anabolic steroids for a long time (Herlitz et al., 2010). The mechanism is associated both with the direct effect of androgens on kidney cells, and with overloading of the kidneys due to a large body weight and high-protein diet. The first sign is protein in the urine, so a urine analysis should be mandatory.
Injectable forms of trenbolone, unlike 17α-alkylated tablet steroids, are not considered classically hepatotoxic. However, elevations in liver enzymes in people using anabolic steroids are often reported, partly due to post-workout muscle damage and partly due to the combination of oral drugs and alcohol.
On the skin side, trenbolone, as a strong androgen, can aggravate acne, oiliness of the skin and accelerate androgenic alopecia in genetically predisposed individuals. In women, the androgenic activity of trenbolone leads to the risk of virilization, some of which are irreversible.
Separately, you should remember the risks of the injection itself: abscesses, infections, nerve injuries, transmission of infections through sharing needles. Off-market products do not undergo sterility testing, and these complications are more common than commonly believed.
Editorial conclusions
Trenbolone enanthate's side effect profile is defined by its strong androgenic action, progestogenic activity, and long-acting ester. The most serious risks concern the cardiovascular system, the hormonal axis and the psyche.
A significant part of the problems — a decrease in HDL, an increase in pressure, erythrocytosis, proteinuria — has no symptoms in the early stages and is detected only in the laboratory. That is why the absence of feeling bad does not mean the absence of harm.
The evidence base for trenbolone itself in humans is limited, and this is not an argument for safety: it means that the true extent of the risks is unknown.
For a deeper understanding of the topic, we recommend our articles on the effects of trenbolone enanthate on the cardiovascular system, on its estrogenic and progestogenic activity and on the tests that should be monitored.
List of used literature
- Pope HG Jr, Wood RI, Rogol A, et al. Adverse health consequences of performance-enhancing drugs: an Endocrine Society scientific statement. Endocr Rev. 2014;35(3):341â375.
- Baggish AL, Weiner RB, Kanayama G, et al. Cardiovascular toxicity of illicit anabolic-androgenic steroid use. Circulation. 2017;135(21):1991â2002.
- Bauer ER, Daxenberger A, Petri T, Sauerwein H, Meyer HH. Characterisation of the affinity of different anabolics and synthetic hormones to the human androgen receptor, human sex hormone binding globulin and to the bovine progestin receptor. APMIS. 2000;108(12):838â846.
- Herlitz LC, Markowitz GS, Farris AB, et al. Development of focal segmental glomerulosclerosis after anabolic steroid abuse. J Am Soc Nephrol. 2010;21(1):163â172.
- Kanayama G, Hudson JI, Pope HG Jr. Long-term psychiatric and medical consequences of anabolic-androgenic steroid abuse: a looming public health concern? Drug Alcohol Depend. 2008;98(1â2):1â12.
- Rahnema CD, Lipshultz LI, Crosnoe LE, et al. Anabolic steroid-induced hypogonadism: diagnosis and treatment. Fertil Steril. 2014;101(5):1271â1279.
- Yarrow JF, McCoy SC, Borst SE. Tissue selectivity and potential clinical applications of trenbolone (17β-hydroxyestra-4,9,11-trien-3-one): a potent anabolic steroid with reduced androgenic and estrogenic activity. Steroids. 2010;75(6):377â389.
