Testosterone, hormone replacement, and sexual health: a clinical FAQ
A FAQ that walks through the curriculum of Harvard Medical School's continuing medical education course on testosterone, hormone replacement, and sexual health, answered from indexed primary sources. Men and women, from the heart to mental health, separating indication from fad.
Is testosterone only good for libido and muscle?
No. It is a systemic hormone, and real deficiency has consequences beyond sex.
Testosterone acts on muscle, bone, metabolism, mood, cognition, and sexual function. Proven deficiency, hypogonadism, is not a cosmetic detail: men with very low endogenous testosterone have, on average, higher all-cause and cardiovascular mortality (Yeap et al., 2024).
Recognizing this, however, is not the same as treating every age-related decline. The diagnosis requires compatible symptoms combined with low total testosterone confirmed on two mornings, not an isolated number (Bhasin et al., 2018).
Who is a candidate for replacement, and when to indicate it?
Deficiency symptoms plus confirmed low testosterone. The isolated age-related number is not treated.
The indication is symptomatic hypogonadism: a clinical complaint, such as low libido, erectile dysfunction, fatigue, or loss of muscle mass, with low testosterone measured correctly. The guideline recommends against treating age-related decline alone without that combination (Bhasin et al., 2018).
The who, when, and why is individual: confirm the diagnosis, rule out reversible causes, align expectations, and monitor. Replacement is not the optimization of a number.
Injection, gel, patch, pellet, or oral: which is the best route?
All replace; the choice is about profile, adherence, and monitoring. High-dose pellets escape the physiological range.
There are several formulations: injectable, transdermal gel or patch, oral, and implants. The principle is the same: restore the adult physiological range, not exceed it (Bhasin et al., 2018). The modern oral route, undecanoate, is absorbed via the lymphatic pathway and does not have the hepatic toxicity of the old 17 alpha alkylated androgens.
The point of concern is the high-dose implants and pellets sold as optimization, which deliver supraphysiological and poorly controllable levels, the opposite of what good practice recommends.
Is replacement bad for the heart? What did TRAVERSE and the FDA change?
The largest trial showed safety, non-inferiority, and not protection. The FDA revised the 2015 warning.
TRAVERSE, in more than five thousand men at high cardiovascular risk, showed non-inferiority in major cardiac events: testosterone did not increase heart attack, stroke, and cardiovascular death (TRAVERSE, 2023). It is safety, not proof of protection. There was, however, more atrial fibrillation and pulmonary embolism in the testosterone arm, which calls for selection and follow-up.
This evidence led the FDA to revise, in 2025, the generic cardiovascular warning it had placed in 2015, aligning the labeling with what the trial showed. The sober reading is the middle one: unfairly demonized in the past, safe when well indicated, and not miraculous. We go deeper in the article Testosterone and the heart.
Does testosterone cause prostate cancer?
Current evidence does not support that physiological replacement causes prostate cancer. Monitoring continues.
The fear comes from the old idea that more testosterone would feed the tumor. Modern evidence does not support this for physiological replacement, and the saturation concept helps to understand why replacement doses do not behave as tumor fuel (Traish and Morgentaler, 2018).
This does not eliminate caution. Replacement is not indicated in active prostate cancer without specialized evaluation, and follow-up with PSA and examination remains part of management (Bhasin et al., 2018).
I want to have children: can I take testosterone replacement?
Exogenous testosterone suppresses sperm production. To preserve fertility, there are other strategies.
Exogenous testosterone replacement inhibits the axis and reduces sperm production, potentially causing infertility. For the man who wishes to preserve fertility, classic replacement is not the first choice (Bhasin et al., 2018).
In these cases, strategies that stimulate the body's own production of testosterone and sperm are used, always with individual evaluation. It is a decision that requires a conversation before starting any therapy.
What are the adverse effects, and how to monitor safely?
The main one is the increase in hematocrit. Monitoring the blood is what makes the therapy safe.
The most consistent laboratory effect is erythrocytosis, the increase in hematocrit, which thickens the blood; and there is a real and early risk of venous thromboembolism, especially in the first months (Walker et al., 2020). For this reason the guideline directs monitoring the hematocrit and suspending or adjusting above 54 percent (Bhasin et al., 2018).
It is worth separating replacement from abuse: supraphysiological doses of anabolic steroids cause cardiac hypertrophy and dysfunction, which is not the picture of monitored physiological replacement (Smit et al., 2021).
In the end, is testosterone over- or under-prescribed?
The two coexist: real hypogonadism underdiagnosed and optimization over-prescribed.
It is the great debate. On one hand, much true hypogonadism goes undiagnosed and untreated; on the other, the prescription of optimization for those who have no deficiency is growing, pushed by pellets and performance clinics.
The ruler that resolves both sides is the same: diagnose correctly and treat those who have an indication, with a physiological dose and monitoring (Bhasin et al., 2018). The problem was never testosterone, it was its use without criteria.
Hormone replacement in menopause: what is it for and is it safe?
It is the most effective treatment for menopausal symptoms, with individual and time-dependent risk and benefit.
Menopausal hormone therapy is the most effective treatment for hot flashes and genitourinary symptoms, with benefit for bone as well. The menopause society holds that, for the symptomatic woman who starts before age 60 or within the first ten years of menopause, the benefit generally outweighs the risk (The Menopause Society, 2022).
The decision is individual: type of hormone, route, dose, and duration depend on the profile and the risk factors. It is not a universal yes or no, it is a personalized calculation.
Can a woman with a history of breast cancer undergo hormone replacement?
As a rule, no: systemic hormone therapy is contraindicated with that history. There are alternatives.
A history of breast cancer is, as a rule, a contraindication to systemic menopausal hormone therapy (The Menopause Society, 2022). The management of symptoms in this group involves non-hormonal options and shared decision-making with oncology.
For local genitourinary symptoms, there are lower-absorption options that can be discussed case by case, always with the team that follows the cancer. The principle is to individualize, not to generalize.
Testosterone in women: what is there evidence for, and what is fad?
The only indication with evidence is hypoactive sexual desire in postmenopause. Energy and anti-aging have no basis.
The global consensus is clear: the only evidence-based indication for testosterone in women is hypoactive sexual desire disorder in postmenopause, at a physiological dose (Davis et al., 2019). The meta-analysis confirms sexual benefit, without benefit for mood, cognition, bone, or body composition (Islam et al., 2019).
Beyond that, testosterone for energy, focus, or anti-aging in women is a fad, and the guidelines recommend against generalized use (Wierman et al., 2014). We go deeper in the article Testosterone replacement in women.
Low sexual desire: is the woman broken?
No. Hypoactive sexual desire is a real diagnosis, with a distress criterion, and has management.
Hypoactive sexual desire disorder is a diagnosis with a criterion of low desire combined with personal distress, and it has a structured approach, biological and psychological (Parish et al., 2021). Naming it already removes the guilt: it is neither weakness nor a character flaw, it is a condition that is evaluated and treated.
When there is an indication, transdermal testosterone at a physiological dose is one of the tools in postmenopause, within a broader plan that includes the couple's context (Davis et al., 2019).
Erectile dysfunction and Peyronie's disease: when to investigate?
Erectile dysfunction can be the first sign of vascular disease. It deserves evaluation, not just a pill.
Erectile dysfunction is rarely just a sexual problem: it is usually an early marker of vascular and metabolic disease, and for this reason the evaluation goes beyond prescribing a PDE5 inhibitor. Low testosterone is one of the causes to investigate, not the only one (Bhasin et al., 2018).
Peyronie's disease, penile curvature from a fibrous plaque, is a distinct entity, with its own evaluation and treatments. The practical message for the patient is to seek evaluation rather than resorting to over-the-counter solutions.
Does testosterone improve depression and mental health?
There is a signal of modest improvement in depressive symptoms, especially at higher doses, but it is not an antidepressant.
A meta-analysis of randomized trials found that testosterone was associated with modest relief of depressive symptoms in men, with a clearer effect at higher doses (Walther et al., 2019). It is a real signal, but it does not turn testosterone into an antidepressant nor does it replace psychiatric treatment.
The honest reading: replacing in deficiency can help mood as part of the picture; promising that testosterone cures depression goes beyond the evidence. Post-finasteride syndrome, cited in courses such as Harvard's, is a distinct and still controversial entity, with limited evidence, and should not be confused with testosterone deficiency.
Why this matters for your care
This FAQ organizes, in questions and answers, the topics of the Testosterone Therapy, HRT, and Sexual Health course from Harvard Medical School (continuing medical education). The answers do not reproduce the speakers' statements; they are built from primary sources verified by DOI and indexed, with the library's line: separate indication from fad, distinguish association from cause, and never prescribe. Hormone replacement and sexual health are matters of medical evaluation and follow-up. Educational content; it does not replace an individual consultation and does not constitute a prescription. The Library gathers the remaining notes.
References
- Bhasin S, Brito JP, Cunningham GR, et al. Testosterone Therapy in Men With Hypogonadism: An Endocrine Society Clinical Practice Guideline. Journal of Clinical Endocrinology & Metabolism. 2018. doi:10.1210/jc.2018-00229
- Lincoff AM, Bhasin S, Flevaris P, et al. Cardiovascular Safety of Testosterone-Replacement Therapy (TRAVERSE). New England Journal of Medicine. 2023. doi:10.1056/NEJMoa2215025
- Yeap BB, Marriott RJ, Dwivedi G, et al. Associations of Testosterone and Related Hormones With All-Cause and Cardiovascular Mortality and Incident Cardiovascular Disease in Men: IPD Meta-analyses. Annals of Internal Medicine. 2024. doi:10.7326/M23-2781
- Walker RF, Zakai NA, MacLehose RF, et al. Association of Testosterone Therapy With Risk of Venous Thromboembolism Among Men With and Without Hypogonadism. JAMA Internal Medicine. 2020. doi:10.1001/jamainternmed.2019.5135
- Smit DL, Buijs MM, de Hon O, et al. (HAARLEM). Anabolic Androgenic Steroids Induce Reversible Left Ventricular Hypertrophy and Cardiac Dysfunction. Frontiers in Reproductive Health. 2021. doi:10.3389/frph.2021.732318
- Traish AM, Morgentaler A. Testosterone, testosterone therapy and prostate cancer. The Aging Male. 2018. doi:10.1080/13685538.2018.1524456
- The North American Menopause Society (2022 Position Statement). The 2022 hormone therapy position statement of The North American Menopause Society. Menopause. 2022. doi:10.1097/GME.0000000000002028
- Davis SR, Baber R, Panay N, et al. Global consensus position statement on the use of testosterone therapy for women. Journal of Clinical Endocrinology & Metabolism. 2019. doi:10.1210/jc.2019-01603
- Islam RM, Bell RJ, Green S, et al. Safety and efficacy of testosterone for women: a systematic review and meta-analysis. The Lancet Diabetes & Endocrinology. 2019. doi:10.1016/S2213-8587(19)30189-5
- Parish SJ, Simon JA, Davis SR, et al. ISSWSH clinical practice guideline for the use of systemic testosterone for HSDD in women. Climacteric. 2021. doi:10.1080/13697137.2021.1891773
- Wierman ME, Arlt W, Basson R, et al. Androgen therapy in women: a reappraisal: an Endocrine Society clinical practice guideline. Journal of Clinical Endocrinology & Metabolism. 2014. doi:10.1210/jc.2014-2260
- Walther A, Breidenstein J, Miller R. Association of Testosterone Treatment With Alleviation of Depressive Symptoms in Men: A Systematic Review and Meta-analysis. JAMA Psychiatry. 2019. doi:10.1001/jamapsychiatry.2018.2734
Educational and scientific content. It does not constitute diagnosis, prescription or individual clinical guidance, and does not replace a medical consultation. Management decisions must be individualized by a physician.