As a male physician, I understand that as men age, they may experience changes that affect their well-being and vitality. In this context, it is natural to seek solutions to feel better, and injectable testosterone therapy often emerges as an appealing option. However, it is crucial to understand what it is, what it is medically indicated for and, above all, the serious risks of using it without proper indication and specialised medical supervision.
Testosterone is the main male sex hormone, essential for the growth, development and function of male sex organs, as well as for the maintenance of typically male characteristics. With age, its levels tend to decline gradually, by about 1% per year after the age of 30-40.
Testosterone injections are forms of synthetic testosterone that are meant to replace the hormone that the body does not produce naturally. Their official and primary medical use is to treat symptoms of low testosterone in men diagnosed with hypogonadism, a medical condition where the body does not produce enough testosterone due to specific problems in the testes, pituitary gland or hypothalamus. In addition, testosterone enanthate and testosterone pellets can be used to stimulate delayed puberty in men.
It is critical to understand that testosterone should not be used to treat symptoms of low testosterone related to normal ageing. A doctor will measure your testosterone levels at least twice before recommending this therapy, and treatment is only indicated in cases where low testosterone levels are accompanied by clinically relevant symptoms.
Many men consider testosterone injection when they experience symptoms such as decreased sexual desire (libido), fewer spontaneous erections, lack of energy, decreased motivation and initiative, sadness or depression, problems with concentration and memory, or sleep disturbances and drowsiness. Although these may be signs of low testosterone levels, it is vital to know that these symptoms are non-specific and may be caused by other medical conditions or lifestyle factors.
For example, fatigue and lack of stamina may be due to:
- Side effects of other medications you are taking
- Obstructive sleep apnoea, a serious disorder where your breathing repeatedly stops during sleep.
- Thyroid disorders, such as hypothyroidism.
- Uncontrolled diabetes
- Depression or anxiety
- Poor lifestyle habits, such as a sedentary lifestyle or inadequate nutrition. In fact, weight loss through a low-calorie diet and regular physical activity can result in a small improvement in testosterone levels.
In many cases, treating these underlying conditions or improving lifestyle can alleviate symptoms and even increase testosterone levels in a natural way.
Injectable testosterone is usually administered into the muscle or under the skin. Dosage is a highly individualised process that a specialist (endocrinologist, urologist or internist) will determine based on laboratory tests of your testosterone levels and your response to treatment. The doctor will then adjust the dose and carefully monitor blood levels to ensure they are therapeutic to minimise risks. There is no safe ‘usual dose’ for self-medication, as each patient has different needs and risks.
The use of testosterone, especially in higher doses or without medical supervision, carries a number of risks and side effects, both physical and psychological, which can be potentially serious and compromise your health.
Common Side Effects:
- Acne and other skin reactions.
- Breast enlargement or pain (gynaecomastia).
- Voice changes, such as hoarseness or a deeper voice
- Pain, redness, bruising, bleeding or hardening at the injection area.
- Fatigue, difficulty falling or staying asleep.
- Mood changes. Irritability.
- Weight gain, headache, joint and back pain.
Serious risks and side effects:
- Heart and cerebrovascular problems: testosterone can increase blood pressure, leading to an increased risk of heart attack or stroke, both of which are potentially life-threatening. A possible link between testosterone therapy and an increased risk of heart disease has been the subject of research. Hypogonadism alone is a risk factor for major adverse cardiovascular events such as myocardial infarction and stroke.
- Prostate conditions: Testosterone may stimulate non-cancerous growth of the prostate (benign prostatic hyperplasia) and accelerate the growth of existing prostate cancer. Testosterone use may increase the risk of developing prostate cancer.
- Respiratory problems: It may worsen sleep apnoea, a potentially serious disorder where breathing stops and starts repeatedly during sleep.
- Haematological conditions: Testosterone may stimulate excessive production of red blood cells, which increases the risk of blood clots. These clots can detach and lodge in the lungs, causing a pulmonary embolism.
- Fertility and testicular function: High doses of testosterone can limit sperm production and cause the testicles to shrink. In young men, it can lead to premature closure of growth plates.
- Liver damage: Although this is more associated with oral formulations, it can cause liver toxicity, including abnormal test results of liver function, cholestasis and jaundice.
- Psychiatric and withdrawal effects: Serious side effects have been reported as a result of testosterone use at higher doses or in forms not prescribed by a physician, including depression, mania, aggressive behaviour, hallucinations or delusions. In addition, if the use of testosterone is stopped suddenly after high doses, withdrawal symptoms such as depression, extreme tiredness, irritability and decreased sex drive may be experienced.
- Lack of clear benefits in healthy older men: Clinical guidelines state that, while testosterone therapy may slightly improve sexual function in some men with hypogonadism, there is little evidence that it improves other functions such as vitality or energy in older men who are, in other respects, healthy.
Testosterone is a controlled substance and requires a prescription and strict monitoring for legitimate medical use. Acquiring or using testosterone without the supervision of a medical specialist is extremely dangerous.
When you self-medicate, you expose yourself to:
- Misdiagnosis: Your symptoms may be due to any other medical condition that requires specific and urgent treatment. Testosterone use may mask these underlying health problems, thus delaying proper diagnosis and treatment.
- Inappropriate doses: Using excessive or incorrect doses significantly increases the risk of serious side effects.
- Lack of monitoring: Without the supervision of a doctor, regular blood tests necessary to monitor testosterone levels, liver function, red blood cell production, prostate status and blood pressure are not performed. This monitoring is essential for early detection and management of any adverse effects.
- Dangerous interactions: Testosterone may interact with other medications you are taking, increasing the risk of complications. For example, it is contraindicated in patients taking nitrates due to the risk of severe hypotension.
- Irreversible damage: Reduced testicular function and decreased sperm production may be permanent, especially with prolonged use and taking high doses.
Conclusion and Final Recommendation
Testosterone is a potent drug that involves specific medical indications and significant risks. If you experience symptoms such as fatigue, decreased libido or lack of vitality, it is most important to consult a specialist.
Dr. David Díaz Sesé
Family and Community Medicine Specialist
Juli 18, 2025
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