Testosterone replacement therapy (TRT) restores testosterone in men whose levels are consistently low and who have symptoms of testosterone deficiency. TRT may improve sex drive, erectile function, muscle mass, bone density, anemia and some mood symptoms when low testosterone is the cause. It is not a general anti-aging treatment, bodybuilding shortcut or guaranteed cure for fatigue and erectile dysfunction.
A proper diagnosis usually requires compatible symptoms and 2 low morning testosterone results. The relevant guidance was published in ****.
TRT for Men at a Glance
| Question | What TRT can do |
|---|---|
| Sex drive | Often improves low libido when low testosterone is the cause |
| Erections | May improve erectile function, but it does not replace standard ED treatment |
| Muscle and body composition | Can increase lean muscle mass and reduce fat mass |
| Bones | Can improve bone mineral density |
| Energy | May help some men, but fatigue has many other causes |
| Mood | May modestly improve well-being or mild mood symptoms |
| Fertility | Can reduce sperm production and make conception more difficult |
| Medical monitoring | Requires follow-up blood tests and monitoring for side effects |
How Does TRT Work?
TRT supplies testosterone through prescribed injections, gels, patches, buccal products or other approved formulations. The goal is usually to bring testosterone into the normal physiological range, not to produce bodybuilding-level hormone concentrations.
Testosterone affects the reproductive system, muscles, bones, red blood cell production, sexual desire and some aspects of mood. TRT replaces testosterone when the body is not producing enough because of a testicular, pituitary, hypothalamic or other medical problem.
What Benefits Can Men Expect From TRT?
TRT can improve some symptoms and physical measures in men with confirmed testosterone deficiency. The results depend on the cause of the deficiency, the severity of the symptoms and the man's overall health.
TRT Can Improve Low Sex Drive
Low testosterone can reduce sexual desire. TRT can improve libido and sexual activity in men who have confirmed testosterone deficiency. The benefit is less likely when testosterone levels are normal or when another condition is causing the sexual symptoms.
TRT May Help Erectile Function
TRT can improve erectile function in some men with low testosterone, particularly when low libido and testosterone deficiency contribute to the problem.
Erectile dysfunction can also result from diabetes, vascular disease, medications, psychological factors or nerve problems. Sildenafil and other phosphodiesterase-5 inhibitors may still be needed.
TRT does not reliably improve erections in men whose testosterone levels are already normal.
TRT Can Increase Lean Muscle Mass
Testosterone supports muscle protein synthesis. In men with hypogonadism, TRT can increase lean body mass and may improve muscle strength.
TRT is different from high-dose anabolic steroid use, which involves substantially different dosing and risks.
TRT Can Improve Bone Density
Testosterone helps maintain bone tissue. TRT can increase bone mineral density in men with testosterone deficiency. An increase in bone density does not automatically prove that TRT prevents fractures.
TRT Can Correct Some Cases of Anemia
Testosterone stimulates red blood cell production. For men whose anemia is related to testosterone deficiency, TRT may increase hemoglobin and hematocrit.
That same effect can become a problem if the red blood cell count rises too much, so regular blood testing is part of treatment.
TRT May Improve Mood, but It Is Not an Antidepressant
Some men report better well-being and mood after starting testosterone treatment. Research suggests that the improvement is generally modest. TRT should not be the primary treatment for clinical depression.
Fatigue and low mood can also be related to sleep apnea, thyroid disease, anemia, medication effects or depression. Those causes need their own evaluation.
What Does TRT Not Reliably Do?
TRT does not reliably:
- Produce major weight loss without changes to diet and activity
- Cure depression
- Treat erectile dysfunction when testosterone levels are normal
- Restore fertility
- Prevent all effects of aging
- Improve athletic performance when testosterone levels are already normal
- Correct fatigue caused by sleep, medical or psychological problems
The Endocrine Society recommends diagnosing hypogonadism only when a man has compatible symptoms or signs and consistently low testosterone results.
Can TRT Reduce Male Fertility?
Yes. TRT can reduce sperm production and may impair fertility.
External testosterone signals the brain to reduce luteinizing hormone and follicle-stimulating hormone. These hormones help the testicles produce sperm, so TRT can suppress sperm production even while increasing testosterone in the bloodstream.
Men who are trying to conceive should tell their clinician before starting TRT. Testosterone treatment is generally not recommended for men planning fertility in the near term. A fertility specialist may consider other treatments that stimulate the body's own testosterone and sperm production.
What Are the Risks and Side Effects of TRT?
TRT can cause:
- An increased red blood cell count
- Acne or oily skin
- Reduced sperm production
- Testicular shrinkage
- Breast tenderness or enlargement
- Fluid retention
- Worsening of untreated sleep apnea
- Increased blood pressure
- Urinary symptoms related to prostate enlargement
The FDA requires testosterone products to include information about blood pressure increases. Product labeling also recommends monitoring blood pressure during treatment.
TRT has not been proven to automatically cause prostate cancer, but men need appropriate prostate risk assessment and monitoring. Long-term safety data remain incomplete, particularly for men using testosterone for age-related symptoms without a clear medical cause.
How Do Doctors Determine Whether a Man Needs TRT?
Doctors determine whether a man needs TRT by reviewing symptoms, confirming low testosterone and checking for causes and treatment risks.
A proper evaluation usually includes:
- Reviewing symptoms, such as low libido, fewer morning erections, loss of muscle mass, unexplained anemia or reduced testicular function.
- Repeating testosterone testing, usually with at least 2 early-morning measurements.
- Checking related hormones, including luteinizing hormone and follicle-stimulating hormone, to help identify whether the problem originates in the testicles or the pituitary-hypothalamus.
- Looking for reversible causes, including obesity, sleep apnea, opioid or corticosteroid use, severe illness and certain medications.
- Assessing treatment safety, including blood count, blood pressure, prostate risk and fertility plans.
One low testosterone result is not enough to diagnose testosterone deficiency. Levels vary with the time of day, illness, sleep and testing methods.
Who Should Be Cautious About TRT?
Some men should not start TRT without further evaluation. This includes men with:
- Current or suspected prostate or breast cancer
- A high hematocrit or abnormally high red blood cell count
- Untreated severe obstructive sleep apnea
- A recent heart attack or stroke
- Uncontrolled heart failure
- Significant urinary symptoms
- A desire to preserve fertility
- Certain clotting or cardiovascular conditions
The decision should consider confirmed testosterone deficiency, the cause of the deficiency, symptom severity, fertility plans and the risks of treatment.
Bottom Line
TRT is most appropriate for men who have both symptoms of testosterone deficiency and repeatedly low morning testosterone levels. Treatment can help with libido and may support muscle, bone, red blood cell production and mood.
Before starting TRT, confirm the diagnosis and identify the cause. Fertility plans, blood pressure, red blood cell count, sleep apnea and prostate risk should all be part of the discussion with a qualified healthcare professional.