Testosterone Education Center

Testosterone therapy (TRT): clinical evidence vs. real-world experience
TRT is used for symptomatic, lab-confirmed low testosterone. Clinical trials show modest but meaningful improvements in sexual function and mood for many men, increases in lean mass and strength, correction of some forms of anemia, and gains in bone density (fracture reduction evidence is mixed). Large safety data suggest cardiovascular risk is not increased when therapy is appropriately prescribed and monitored. As with any hormone therapy, individualized dosing and regular labs (hematocrit, lipids, PSA as appropriate) are essential. Note that exogenous testosterone can suppress sperm production—use alternatives if you’re trying to conceive.

Beyond trials, there’s a wide range of real-world reports—some men describe better energy, focus, and libido within weeks, while others need dose/formulation adjustments to feel their best. Responses vary by baseline health, delivery method (gel vs. injections), and adherence.

Want to go deeper? Click the FAQ items and Clinical Studies buttons below to explore the evidence, safety considerations, and practical tips so you can make an informed decision.

What is TRT and who is it for?
Testosterone replacement therapy (TRT) treats symptomatic hypogonadism confirmed by consistently low morning testosterone on repeat testing. Diagnosis and monitoring follow society guidelines.
Endocrine Society Guideline AUA Guideline
Sexual function and mood: what do RCTs show?
The NIH-funded Testosterone Trials (TTrials) showed modest but significant improvements in sexual activity, desire, and erectile function; mood/depressive symptoms improved modestly.
NEJM: TTrials (Sexual/Vitality) NEJM Review (2025)
Lean mass & strength: what to expect?
Trials and recent reviews show increases in lean mass and small improvements in maximal strength; changes in daily function vary by baseline health and training.
NEJM Review (2025)
Bone: density vs. fractures
Testosterone increased spine/hip volumetric bone density and estimated strength over 1 year in older men with low T. A newer large trial of men with hypogonadism didn’t show fewer clinical fractures—so BMD improves, but fracture reduction isn’t yet proven.
JAMA Intern Med: Bone Density Trial NEJM (2024): Fractures Trial
Anemia: does TRT help low hemoglobin?
In the TTrials anemia study, testosterone corrected anemia more often than placebo in men with low T—both with unexplained and known-cause anemia.
JAMA Intern Med: Anemia Trial
Heart safety: where does the evidence land?
The 2023 TRAVERSE RCT (men with hypogonadism and high CV risk) found TRT was non-inferior to placebo for major adverse cardiac events over ~2.7 years. Earlier imaging work showed increased non-calcified plaque volume at 12 months—clinical meaning remains uncertain.
NEJM 2023: TRAVERSE CV Safety JAMA 2017: Coronary Plaque Study
Fertility: can I be on TRT if I want kids?
Exogenous testosterone suppresses pituitary LH/FSH and can markedly lower sperm counts. Major guidelines advise avoiding TRT if you’re trying to conceive; alternatives (hCG, SERMs) may be considered with a reproductive urologist.
AUA: Fertility Statements Review: Testosterone is a Contraceptive
Monitoring & common risks (Hct, OSA, PSA)
Expect labs at baseline, 3–6 months, then at least annually. Watch for erythrocytosis (hematocrit ↑); many guidelines act if Hct ≥54%. Untreated sleep apnea can worsen with TRT. Prostate screening follows age/risk guidelines.
Endocrine Society: Monitoring Review: Erythrocytosis Thresholds Review: TRT & Sleep Apnea
Gels vs injections—does it matter?
Choice depends on preference, absorption, and stability of levels. Injections (IM or SC) and transdermals are both guideline-supported; we’ll match the method to your goals and lab response.
Guideline: Formulations
Anecdotes: energy, mood, libido (varies by individual)
Many users report improved energy, mood, and libido within weeks; others need dose/formulation tweaks (“dialing in”) or report limited change—illustrating individual variability.
Thread: Early Wins Thread: Pros & Cons
Anecdotes: gels vs injections & practical tips
Community reports highlight steadier symptoms for some on split-dose injections; others prefer gels for needle-free convenience. Absorption and side-effect profiles differ person-to-person.
Thread: Gel vs Injection Thread: Methods Compared
Anecdotes: fertility journeys (hCG/SERMs)
Real-world stories describe using hCG ± SERMs to maintain or restore sperm counts when coming off or adjusting TRT—always coordinate with a fertility specialist.
Thread: Fertility after TRT Thread: Protocol While on TRT