Hormone Therapy
Testosterone Replacement Therapy: Uses, Evidence, and Safety
Medically reviewed by HealthRX.com Medical Team · Last reviewed
What is testosterone replacement therapy?
TRT is the use of prescribed testosterone to bring low levels back to the middle of the normal range in men who have hypogonadism. Hypogonadism means both low testosterone on testing and matching symptoms. Testosterone by itself is not a diagnosis, so treatment targets the whole picture, not a single number.
The Endocrine Society and AUA both stress confirming low testosterone with two morning blood tests before starting, because a single low reading is often normal on repeat. [1][3]
What forms of testosterone are used?
The main forms are injections, skin gels and implanted pellets, each with trade-offs in convenience, steadiness of levels and cost. All standard forms suppress the body's own production and sperm counts, which matters for men who want children.
| Form | Schedule | Notes |
|---|---|---|
| Cypionate or enanthate injection | Weekly to every few weeks | Low cost; peaks and troughs possible |
| Transdermal gel | Daily | Steady levels; can transfer to others by skin contact |
| Pellets | Every 3 to 4 months | Convenient; dose fixed once implanted |
What does the evidence show TRT does?
The clearest benefit is sexual function. In the Testosterone Trials, testosterone improved sexual activity, desire and erectile function in older men with low levels. It modestly helped mood, anemia and bone. Energy and physical function fell short of their main goals, so those claims are weaker.
Is testosterone therapy safe?
Testosterone can raise red blood cell counts, suppress fertility and increase blood pressure, so monitoring matters. The 2023 TRAVERSE trial found no increase in major heart events versus placebo in men with genuine low testosterone, but more atrial fibrillation, lung clots and kidney injury.
Is testosterone therapy FDA approved?
Testosterone is FDA approved for men with hypogonadism from a medical cause and is a Schedule III controlled substance. FDA labeling states that safety and benefit for age-related low testosterone are not established, so treating normal aging as a deficiency is outside the approved use.
In 2025 the FDA updated testosterone labeling to reflect the TRAVERSE results, removing older cardiovascular boxed-warning language while adding a warning that testosterone can raise blood pressure. The limitation on age-related use remained. [2]
How does Testosterone Replacement Therapy compare with other peptides?
| Injection | Gel | Pellet | |
|---|---|---|---|
| Frequency | Weekly to monthly | Daily | Every 3 to 4 months |
| Levels | Peaks and troughs | Steady | Steady |
| Transfer risk | None | Yes, by skin contact | None |
| Cost | Lowest | Higher | Procedure based |
Frequently asked questions
Who qualifies for testosterone therapy?
Men with both symptoms and low testosterone confirmed on two separate morning blood tests. A single low reading is often normal on repeat, so guidelines require confirmation before treatment.
Does TRT increase heart attack risk?
The 2023 TRAVERSE trial found no increase in major cardiac events versus placebo in men with confirmed low testosterone. It did find more atrial fibrillation, lung clots and kidney injury, and testosterone can raise blood pressure.
Will it affect my fertility?
Yes. Standard testosterone lowers your body's own production and sperm counts, which can cause temporary infertility. Men who want children soon should ask about enclomiphene or hCG, which help preserve fertility.
Is testosterone good for anti-aging?
No. FDA labeling states that benefit for age-related low testosterone is not established. TRT is approved for hypogonadism from a medical cause, not for normal aging or men with normal levels.
What are the most common side effects?
A rise in red blood cell count (hematocrit), acne, fluid retention, and with gels the risk of transfer to others by skin contact. Blood counts, PSA and blood pressure are monitored during treatment.
Citations
- Bhasin S, et al. Testosterone Therapy in Men With Hypogonadism: An Endocrine Society Clinical Practice Guideline. J Clin Endocrinol Metab. 2018;103(5):1715-1744.
- Lincoff AM, et al. Cardiovascular Safety of Testosterone-Replacement Therapy (TRAVERSE). N Engl J Med. 2023;389(2):107-117.
- Mulhall JP, et al. Evaluation and Management of Testosterone Deficiency: AUA Guideline. J Urol. 2018;200(2):423-432.
- Snyder PJ, et al. Effects of Testosterone Treatment in Older Men. N Engl J Med. 2016;374(7):611-624.
- Wiehle RD, et al. Enclomiphene citrate stimulates testosterone production while preventing oligospermia. Fertil Steril. 2014;102(3):720-727.
This guide is educational and is not a substitute for individualized medical advice. Testosterone Replacement Therapy is prescription-only and requires evaluation by a licensed provider.