Testosterone therapy benefits: the evidence by the numbers

Testosterone therapy benefits are measurable in men with confirmed low testosterone. The TestES individual participant data meta-analysis, published in Lancet Healthy Longevity in 2023, found an IIEF-15 total score mean difference of 5.52 (95% CI 3.95 to 7.10). Sexual function, lean mass, strength, bone density and anemia all improve. Fractures and vitality do not.

Key takeaways

• Corona 2017, European Urology, 14 placebo-controlled trials and 2,298 men: IIEF erectile function mean difference 2.31 (95% CI 1.41 to 3.22).
• Skinner 2018, Journal of Cachexia, Sarcopenia and Muscle, 31 randomized trials: fat-free mass effect size 1.20 (95% CI 0.91 to 1.49).
• T4DM, Lancet Diabetes and Endocrinology, 2021: relative risk 0.59 (95% CI 0.43 to 0.80) for reaching the two-hour diabetes glucose threshold at two years.
• Snyder 2017, JAMA Internal Medicine: treatment effect of 6.8 percent (95% CI 4.8 to 8.7) on spine trabecular volumetric bone density.
• The TRAVERSE anemia substudy, JAMA Network Open, 2023: anemia corrected in 44.6 percent of treated men versus 39.2 percent on placebo at 48 months (p = 0.002).
• The same trial found more clinical fractures on testosterone, 91 (3.50 percent) versus 64 (2.46 percent), hazard ratio 1.43 (95% CI 1.04 to 1.97), reported by Snyder in 2024.

Who do the testosterone therapy benefits apply to?

Everything on this page applies to men with confirmed low testosterone, with symptoms and with other causes considered. It does not apply to men whose testosterone is normal. What testing your own case needs is a decision for your doctor or nurse practitioner.

That boundary is written into the rules, not only into the research. Health Canada’s product monograph for oral testosterone undecanoate, authorized 12 December 2025, requires deficiency to be confirmed by two separate validated biochemical assays using morning testosterone, and states it should not be used for non-specific symptoms if deficiency has not been demonstrated.

The European Association of Urology guidelines, 2026 edition, strongly recommend a total testosterone threshold of 12 nmol/L (3.5 ng/mL) for late-onset hypogonadism, measured fasting between 07:00 and 10:00 and confirmed on two separate occasions. Isidori’s 2005 meta-analysis in Clinical Endocrinology, 17 trials and 656 subjects, found benefit below 12 nmol/L and no effect in eugonadal men. See our page on how low testosterone is diagnosed in Canada.

What does testosterone therapy do for sexual function?

Sexual function is the most consistent benefit domain, and three large analyses agree on it. Corona’s 2017 meta-analysis in European Urology pooled 14 placebo-controlled trials with 2,298 participants, mean age 60.2 years and mean follow-up 40.1 weeks, and found a mean difference of 2.31 (95% CI 1.41 to 3.22) versus placebo on the IIEF erectile function domain, p less than 0.0001. Improvement was 1.47 (95% CI 0.90 to 2.03) in men below 12 nmol/L and 2.95 (95% CI 1.86 to 4.03) in men below 8 nmol/L, and the authors state the effect was smaller in men with diabetes and obesity.

The individual participant data

Hudson’s 2023 TestES analysis in Lancet Healthy Longevity is the highest evidence tier available here, covering 35 studies and 5,601 participants, with 17 trials supplying raw participant-level data on 3,431 men of median age 67. The IIEF-15 total score mean difference was 5.52 (95% CI 3.95 to 7.10) and the erectile function subscore was 2.14 (95% CI 1.40 to 2.89), reaching the minimal clinically important difference for mild erectile dysfunction. The benefit did not depend on age, obesity, diabetes or baseline testosterone.

The newest large trial

Pencina’s 2024 report in the Journal of Clinical Endocrinology and Metabolism covered a nested randomized study inside TRAVERSE: 1,161 men with low libido. Sexual activity improved more than placebo, a between-group difference of 0.49 acts per day (95% CI 0.19 to 0.79) at 6 months and 0.47 (95% CI 0.11 to 0.83) at 12 months, maintained at 24 months. Erectile function did not improve in that substudy, which is why the erectile evidence rests on Corona 2017 and Hudson 2023. The detail is in our page on testosterone and erectile function.

How much lean mass and strength does testosterone therapy add?

Lean mass and strength rise measurably, and the size of the change depends on how the medication is given. Skinner’s 2018 meta-analysis in the Journal of Cachexia, Sarcopenia and Muscle pooled 31 randomized trials for fat-free mass and 17 for strength. Fat-free mass increased with an effect size of 1.20 (95% CI 0.91 to 1.49), total body strength 0.90 (95% CI 0.67 to 1.14), lower-extremity strength 0.77 (95% CI 0.45 to 1.08) and upper-extremity strength 1.13 (95% CI 0.78 to 1.47), all p less than 0.001.

Route made a difference. Intramuscular administration gave a 5.7 percent increase in fat-free mass and 10 to 13 percent increases in total body strength, while transdermal administration gave a 1.7 percent increase in fat-free mass and no change in lower-extremity strength versus placebo (effect size 0.26, p = 0.26).

Corona’s 2015 meta-analysis in the European Journal of Endocrinology, covering 59 randomized controlled trials with 3,029 treated men and 2,049 controls, found reduced fat mass and increased lean mass, but no significant change in body weight, waist circumference or body mass index. Body composition change and weight loss are not the same thing.

Does that translate into walking better?

Partly. Snyder’s 2016 T-Trials report in the New England Journal of Medicine, covering 790 men aged 65 and older with serum testosterone below 275 ng/dL treated for one year, found the proportion with an increase of at least 50 m in 6-minute walking distance did not differ significantly within the Physical Function Trial itself, but did differ when men from all three trials were included, 20.5 percent on testosterone versus 12.6 percent on placebo (P = 0.003).

Does testosterone therapy change blood sugar?

It can, in a specific population and alongside other measures. The T4DM trial, published by Wittert in Lancet Diabetes and Endocrinology in 2021, randomized 1,007 men aged 50 to 74, all enrolled in a lifestyle program. At two years, a two-hour glucose of 11.1 mmol/L or higher on oral glucose tolerance testing occurred in 87 of 413 men (21 percent) on placebo versus 55 of 443 (12 percent) on testosterone, a relative risk of 0.59 (95% CI 0.43 to 0.80, p = 0.0007).

Two caveats belong with that result. Participants were selected to be without pathological hypogonadism, and hematocrit above 54 percent occurred in 106 of 491 men (22 percent) on testosterone versus 6 of 484 (1 percent) on placebo, which the authors call potentially treatment limiting. See our page on testosterone, blood sugar and metabolic health.

What happens to bone density on testosterone therapy?

Bone density and estimated bone strength rise, and that has been measured precisely. Snyder’s 2017 bone trial in JAMA Internal Medicine, part of the T-Trials, was a placebo-controlled double-blind study in 211 men of mean age 72.3 years over 12 months, using quantitative computed tomography.

Spine trabecular volumetric bone mineral density rose 7.5 percent on testosterone versus 0.8 percent on placebo, a treatment effect of 6.8 percent (95% CI 4.8 to 8.7, p less than 0.001). Estimated spine trabecular bone strength rose 10.8 percent versus 2.4 percent, a treatment effect of 8.5 percent (95% CI 6.0 to 10.9, p less than 0.001). The authors said a larger trial would be needed to show whether this means fewer fractures. It did not.

Can testosterone therapy correct anemia?

Yes, and this is one of the most durable benefit findings available. Pencina’s 2023 report in JAMA Network Open, a nested randomized study within TRAVERSE covering 5,204 men of whom 815 had anemia, found anemia corrected in a greater proportion of treated men at every time point: 41.0 percent versus 27.5 percent at 6 months, 45.0 versus 33.9 at 12 months, 42.8 versus 30.9 at 24 months, 43.5 versus 33.2 at 36 months and 44.6 versus 39.2 at 48 months (p = 0.002). The abstract reports proportions rather than a single effect estimate with a confidence interval.

Roy’s 2017 analysis in JAMA Internal Medicine, covering 788 men aged 65 and older of whom 62 had unexplained anemia, found hemoglobin rose by 1.0 g/dL or more in 54 percent on testosterone versus 15 percent on placebo (adjusted odds ratio 31.5, 95% CI 3.7 to 277.8, p = 0.002). That interval is wide because the subgroup is small. Six men who were not anemic at baseline reached a hemoglobin above 17.5 g/dL, which is why blood counts are checked, as our page on monitoring on testosterone therapy in Canada sets out.

Does testosterone therapy improve quality of life?

A government-funded health technology assessment concluded that it does. The TestES evidence synthesis by Cruickshank and Brazzelli, published in Health Technology Assessment in 2024, covered 35 trials and 5,601 randomized participants. In the authors’ own words, testosterone replacement therapy “improved quality of life and sexual function in almost all patient subgroups” and “improves sexual function and quality of life without adverse effects on blood pressure, serum lipids or glycaemic markers.”

The same report found cardiovascular or cerebrovascular events in 120 of 1,601 men (7.5 percent) on testosterone versus 110 of 1,519 (7.2 percent) on placebo, odds ratio 1.07 (95% CI 0.81 to 1.42, p = 0.62), with too few deaths to assess mortality.

Summary table of the main findings

What the evidence does not show

Four findings run against the benefit picture, and each has numbers attached.

Fractures did not fall. Snyder’s 2024 report in the New England Journal of Medicine, covering 5,204 men followed for a median of 3.19 years, found clinical fracture in 91 men (3.50 percent) on testosterone versus 64 (2.46 percent) on placebo, hazard ratio 1.43 (95% CI 1.04 to 1.97). Bone density improves, but the largest trial did not show fewer fractures, and fracture prevention is not a reason to start.

Diabetes prevention did not replicate. Bhasin’s 2024 report in JAMA Internal Medicine covered 1,175 men with prediabetes and 3,880 with diabetes inside TRAVERSE. Progression to diabetes did not differ between groups, and the authors state that testosterone alone should not be used to prevent or treat diabetes. T4DM showed prevention in men selected for impaired glucose tolerance in a lifestyle program; TRAVERSE, in a different population, did not.

Vitality was null in the T-Trials. Snyder’s 2016 report in the New England Journal of Medicine, covering 790 men aged 65 and older with serum testosterone below 275 ng/dL, found no significant benefit for vitality on the FACIT-Fatigue scale, although men on testosterone reported slightly better mood and lower severity of depressive symptoms. The same program significantly increased sexual activity, desire and erectile function. The authors state the number of participants was too few to draw conclusions about the risks of treatment.

The depression evidence conflicts. Walther’s 2019 meta-analysis in JAMA Psychiatry, covering 27 randomized placebo-controlled trials and 1,890 men, found a small reduction in depressive symptoms versus placebo, Hedges g 0.21 (95% CI 0.10 to 0.32), response odds ratio 2.30 (95% CI 1.30 to 4.06), with high heterogeneity. Hudson’s 2023 TestES analysis found no significant improvement on the Beck Depression Inventory. Both stand, and they disagree. See our page on testosterone, energy and mood.

Frequently asked questions

Does testosterone therapy help men with normal testosterone levels?

No. The trials summarized here enrolled men with confirmed low testosterone, and Isidori’s 2005 meta-analysis in Clinical Endocrinology reported no effect in eugonadal men. Health Canada’s product monograph for oral testosterone undecanoate, authorized 12 December 2025, states the product should not be used to treat non-specific symptoms suggestive of hypogonadism if deficiency has not been demonstrated. Speak with your doctor or pharmacist.

How large is the erectile function benefit?

Corona’s 2017 meta-analysis in European Urology found a mean difference of 2.31 (95% CI 1.41 to 3.22) on the IIEF erectile function domain across 14 placebo-controlled trials in 2,298 men. Hudson’s 2023 TestES analysis found an erectile function subscore difference of 2.14 (95% CI 1.40 to 2.89), which met the minimal clinically important difference for mild erectile dysfunction.

Does the route of administration change the result?

For muscle outcomes, yes. Skinner’s 2018 meta-analysis in the Journal of Cachexia, Sarcopenia and Muscle reported a 5.7 percent increase in fat-free mass and 10 to 13 percent increases in total body strength with intramuscular administration, versus a 1.7 percent increase in fat-free mass with transdermal administration. Transdermal treatment showed no change in lower-extremity strength versus placebo (effect size 0.26, p = 0.26).

Will testosterone therapy make me lose weight?

Randomized trial evidence does not support that. Corona’s 2015 meta-analysis in the European Journal of Endocrinology, covering 59 randomized trials, found reduced fat mass and increased lean mass but no significant change in body weight, waist circumference or body mass index. Body composition and body weight are different measurements, and only the first changed consistently in randomized trials.

Does testosterone therapy prevent fractures?

No. Snyder’s 2024 report in the New England Journal of Medicine, covering 5,204 men followed for a median of 3.19 years, found clinical fractures in 91 men (3.50 percent) on testosterone versus 64 (2.46 percent) on placebo, hazard ratio 1.43 (95% CI 1.04 to 1.97). Bone density improves, measured by quantitative computed tomography, but fracture reduction has not been shown.

What is the strongest single piece of evidence in this field?

For benefit, the TestES individual participant data meta-analysis published by Hudson in Lancet Healthy Longevity in 2023, because it used raw participant-level data from 17 trials and 3,431 men rather than pooled summary statistics. For safety, the TRAVERSE trial published by Lincoff in the New England Journal of Medicine in June 2023, covered in our page on the TRAVERSE trial.

References

1. Corona G, et al. 2017. Meta-analysis of Results of Testosterone Therapy on Sexual Function Based on International Index of Erectile Function Scores. European Urology. PMID 28434676. DOI: https://doi.org/10.1016/j.eururo.2017.03.032
2. Hudson J, et al. 2023. Symptomatic benefits of testosterone treatment in patient subgroups: a systematic review, individual participant data meta-analysis, and aggregate data meta-analysis. Lancet Healthy Longevity. PMID 37804846. DOI: https://doi.org/10.1016/S2666-7568(23)00169-1
3. Pencina KM, et al. 2024. Effect of Testosterone Replacement Therapy on Sexual Function and Hypogonadal Symptoms in Men with Hypogonadism. Journal of Clinical Endocrinology and Metabolism. PMID 37589949. DOI: https://doi.org/10.1210/clinem/dgad484
4. Cunningham GR, et al. 2016. Testosterone Treatment and Sexual Function in Older Men With Low Testosterone Levels. Journal of Clinical Endocrinology and Metabolism. PMID 27355400. DOI: https://doi.org/10.1210/jc.2016-1645
5. Snyder PJ, et al. 2016. Effects of Testosterone Treatment in Older Men. New England Journal of Medicine. PMID 26886521. DOI: https://doi.org/10.1056/NEJMoa1506119
6. Isidori AM, et al. 2005. Effects of testosterone on sexual function in men: results of a meta-analysis. Clinical Endocrinology. PMID 16181230. DOI: https://doi.org/10.1111/j.1365-2265.2005.02350.x
7. Skinner JW, et al. 2018. Muscular responses to testosterone replacement vary by administration route: a systematic review and meta-analysis. Journal of Cachexia, Sarcopenia and Muscle. PMID 29542875. DOI: https://doi.org/10.1002/jcsm.12291
8. Corona G, et al. 2015. THERAPY OF ENDOCRINE DISEASE: Testosterone supplementation and body composition: results from a meta-analysis study. European Journal of Endocrinology. PMID 26537862. DOI: https://doi.org/10.1530/EJE-15-0262
9. Wittert G, et al. 2021. Testosterone treatment to prevent or revert type 2 diabetes in men enrolled in a lifestyle programme (T4DM): a randomised, double-blind, placebo-controlled, 2-year, phase 3b trial. Lancet Diabetes and Endocrinology. PMID 33338415. DOI: https://doi.org/10.1016/S2213-8587(20)30367-3
10. Snyder PJ, et al. 2017. Effect of Testosterone Treatment on Volumetric Bone Density and Strength in Older Men With Low Testosterone: A Controlled Clinical Trial. JAMA Internal Medicine. PMID 28241231. DOI: https://doi.org/10.1001/jamainternmed.2016.9539
11. Pencina KM, et al. 2023. Efficacy of Testosterone Replacement Therapy in Correcting Anemia in Men With Hypogonadism: A Randomized Clinical Trial. JAMA Network Open. PMID 37889486. DOI: https://doi.org/10.1001/jamanetworkopen.2023.40030
12. Roy CN, et al. 2017. Association of Testosterone Levels With Anemia in Older Men: A Controlled Clinical Trial. JAMA Internal Medicine. PMID 28241237. DOI: https://doi.org/10.1001/jamainternmed.2016.9540
13. Cruickshank M, Brazzelli M, et al. 2024. The effects and safety of testosterone replacement therapy for men with hypogonadism: the TestES evidence synthesis and economic evaluation. Health Technology Assessment. PMID 39248210. DOI: https://doi.org/10.3310/JRYT3981
14. Walther A, et al. 2019. Association of Testosterone Treatment With Alleviation of Depressive Symptoms in Men: A Systematic Review and Meta-analysis. JAMA Psychiatry. PMID 30427999. DOI: https://doi.org/10.1001/jamapsychiatry.2018.2734
15. Snyder PJ, et al. 2024. Fracture substudy of the TRAVERSE trial (full title unknown from the sources used for this page). New England Journal of Medicine. PMID 38231621. DOI: https://doi.org/10.1056/NEJMoa2308836
16. Bhasin S, et al. 2024. Diabetes substudy of the TRAVERSE trial (full title unknown from the sources used for this page). JAMA Internal Medicine. PMID 38315466. DOI: https://doi.org/10.1001/jamainternmed.2023.7862
17. Lincoff AM, et al. 2023. Cardiovascular Safety of Testosterone-Replacement Therapy. New England Journal of Medicine. PMID 37326322. DOI: https://doi.org/10.1056/NEJMoa2215025
18. Health Canada. Product monograph, testosterone undecanoate oral capsules. Authorized 12 December 2025. https://pdf.hres.ca/dpd_pm/00082762.PDF
19. European Association of Urology. Guidelines on Sexual and Reproductive Health, male hypogonadism chapter, 2026 edition, limited update March 2026. https://uroweb.org/guidelines/sexual-and-reproductive-health/chapter/male-hypogonadism

This page is educational information, not medical advice. Testosterone is a prescription medication and a controlled substance in Canada. Talk to your doctor or pharmacist about your own situation.