Is Testosterone Replacement Therapy Safe for Men? What the 2023 TRAVERSE Trial Changed

Key Takeaways

• The 2023 TRAVERSE trial (NEJM) found testosterone replacement therapy did not increase heart attacks, strokes, or cardiovascular death versus placebo in 5,246 men.
• Small but real increases in atrial fibrillation and venous clot events warrant pre-treatment cardiovascular and clotting evaluation.
• Modern research (saturation model, Morgentaler & Traish) does not support the longstanding fear that testosterone causes prostate cancer in men with normal prostates.
• VIMC prescribes bioidentical testosterone through credible compounding pharmacies, along with clomiphene, hCG, and gonadorelin as endogenous-stimulation options for men who prefer to support their own production.
• Age is treated as a clinical guide, not a categorical limit; candidacy is determined by individualized assessment.

For more than a decade, men considering testosterone replacement therapy faced a confusing question with shifting answers: is TRT safe? A handful of observational studies in the early 2010s raised concerns about heart attacks and strokes. The FDA added a cardiovascular warning to testosterone labels in 2015. The debate dragged on, leaving men and their providers without a definitive answer.

That changed in 2023. The TRAVERSE trial, the largest randomized cardiovascular safety study ever conducted on testosterone therapy, was designed to settle the question. This guide walks through what TRAVERSE actually found, which risks remain real and require monitoring, how the science on prostate cancer has shifted, and how the Venus Integrative Medical Center (VIMC) team in Mesa, Arizona approaches male hormone care with the rigor the evidence now supports.

The Cardiac Question Is Settled: What the TRAVERSE Trial Actually Found

TRAVERSE was a multicenter, double-blind, placebo-controlled trial that enrolled 5,246 men aged 45 to 80 with confirmed hypogonadism and either established cardiovascular disease or multiple cardiac risk factors. Half received daily transdermal testosterone gel titrated to a normal range; half received placebo. The primary endpoint was major adverse cardiovascular events, including heart attack, stroke, and cardiovascular death.

Published in the New England Journal of Medicine in 2023 (Lincoff et al.), the trial reported that testosterone therapy was non-inferior to placebo for major adverse cardiac events. The event rate was effectively identical across groups. The trial was specifically designed to answer the cardiac safety question that had hung over TRT for a decade, and it answered it with a level of statistical rigor that observational data could never match.

A subsequent secondary analysis of TRAVERSE data found a reduction in new-onset type 2 diabetes among men with prediabetes who received testosterone compared with placebo. While exploratory, it adds to broader evidence connecting testosterone optimization with metabolic health.

Honest Disclosure: The Atrial Fibrillation and Clot Signals

TRAVERSE also identified two signals worth open discussion.

The testosterone group showed a small but statistically meaningful increase in atrial fibrillation (AF) events compared with placebo. For men with pre-existing rhythm concerns, this is clinically relevant. There was also a small absolute increase in venous thromboembolism (VTE) events, around 1.7% versus 1.2%, consistent with prior data summarized by Ayele and colleagues in Thrombosis Research (2021). This matters most for men with prior clot history, thrombophilia, or other VTE risk factors.

Neither finding overturns the primary safety conclusion of TRAVERSE, but both reinforce why a thorough cardiovascular and clotting workup before starting TRT is essential. At VIMC, this is built into the standard pre-treatment evaluation rather than added on later.

The Prostate Cancer Fear: How the Science Has Shifted

For decades, medicine assumed testosterone fuels prostate cancer. The belief traces back to a 1941 study showing that castration caused advanced prostate cancer to regress. The intuitive leap, that more testosterone must mean more cancer risk, dominated practice for generations.

Modern research tells a different story. The saturation model, formalized by Morgentaler and Traish in European Urology (2009), demonstrates that prostate androgen receptors saturate at relatively low testosterone levels. Once that saturation point is reached, additional testosterone does not stimulate further prostate growth. Restoring a deficient man to normal testosterone does not push the prostate past a meaningful growth threshold.

Subsequent research (Khera et al., European Urology, 2013) has shown that men with low testosterone often present with more aggressive prostate cancer and worse outcomes than men with normal levels. TRAVERSE itself reported no increase in prostate cancer among TRT-treated men. At VIMC, prostate safety is monitored with free and total PSA, with multiparametric MRI and specialist referral when indicated.

Estrogen, Not Testosterone: Why Metabolite Monitoring Matters

There is a more nuanced dimension to the hormone-cancer conversation. Testosterone converts to estrogen through aromatase activity, and those estrogens must be properly metabolized and cleared from the body. When detoxification pathways are impaired, certain genotoxic estrogen metabolites can accumulate. Research published in Biochimica et Biophysica Acta (Cavalieri et al., 2006) documented how catechol estrogen quinones can form DNA adducts; the mechanism is most established in breast cancer research, with emerging parallel evidence in prostate tissue.

Practically, this means tracking both estradiol and estrone, not just testosterone, when prescribing male hormone therapy. VIMC monitors both, which is more thorough than the standard panels offered by many TRT clinics.

The Real Side Effects Worth Monitoring

Erythrocytosis (elevated red blood cell count) is the most consistently documented side effect of testosterone therapy. Testosterone stimulates red blood cell production, which is not harmful at controlled levels but raises blood viscosity and clot risk when significantly elevated. A 2021 JCEM cohort study by Madsen and colleagues, in trans men using testosterone, observed erythrocytosis in roughly 11% of users; ranges are similar or somewhat lower in cisgender men on standard doses. Risk climbs with longer treatment, tobacco use, sleep apnea, COPD, obesity, and metabolic syndrome. At VIMC, hematocrit is tracked continuously and managed through dose adjustment, delivery method change, or therapeutic phlebotomy.

Hair thinning can occur in men genetically predisposed to male-pattern baldness, since testosterone converts to dihydrotestosterone (DHT) via 5-alpha reductase and DHT acts on susceptible follicles. VIMC measures DHT routinely and discusses this proactively before therapy begins.

Sleep apnea can be unmasked or worsened by testosterone in predisposed men. Pre-treatment screening for symptoms such as loud snoring, daytime fatigue, large neck circumference, and obesity is part of the VIMC workup.

What Younger Men Need to Know About TRT and Fertility

Exogenous testosterone suppresses the hypothalamic-pituitary-gonadal axis. When the brain detects adequate testosterone from an outside source, it dials down its signal to the testes, reducing both endogenous testosterone production and sperm production. For men who may want biological children, this must be addressed before therapy begins.

VIMC screens every male hormone patient for fertility goals at the outset. For men who want to preserve fertility, options include clomiphene, human chorionic gonadotropin (hCG), and certain FDA-approved peptides that support hormone optimization without the same degree of spermatogenic suppression. Fertility effects of standard TRT are typically reversible after discontinuation, but recovery time varies and full recovery is not guaranteed. Testicular atrophy from suppressed endogenous production is also an expected change with exogenous TRT and is discussed openly during informed consent rather than discovered later.

Benefits That Often Get Underplayed in the Safety Conversation

Safety is essential, but the well-documented benefits of properly managed TRT in men with confirmed deficiency deserve equal billing.

• Energy and motivation: noticeable improvement within weeks of reaching therapeutic levels.
• Body composition: increased lean muscle, reduced fat mass, improved metabolic markers.
• Sexual health: improved libido, erectile function, and sexual satisfaction.
• Mood and cognition: reduced brain fog, improved mood stability.
• Bone density: maintained bone mineral density, reducing fracture risk with age.
• Metabolic support: improvements in lipid profile, blood sugar, and blood pressure consistent with the TRAVERSE diabetes-prevention finding.

How TRT Is Delivered: Pellets, Injections, and Topicals

Testosterone therapy is customized to each patient's goals, lifestyle, and lab response. VIMC prescribes bioidentical hormones through credible compounding pharmacies. Available routes include:

• Injectable testosterone (intramuscular or subcutaneous): reliable, cost-effective, with flexible dosing.
• Testosterone pellets: slow, consistent release over several months without daily administration.
• Topical creams or gels: convenient daily application, easy dose adjustment based on labs.

Each route has different absorption patterns, hematocrit implications, and aromatization profiles. The choice is made based on lifestyle, risk factors, and lab response, not by default.

Endogenous Stimulation: Clomiphene and hCG as Alternatives to TRT

Not every man with low testosterone needs or wants exogenous testosterone. For some patients, stimulating the body's own production is the more appropriate path. Clomiphene citrate works upstream by signaling the hypothalamus and pituitary to release more luteinizing hormone (LH) and follicle-stimulating hormone (FSH), which in turn drives the testes to produce more testosterone. Human chorionic gonadotropin (hCG) acts directly on the testes to stimulate testosterone production while also supporting testicular volume and intratesticular function.

VIMC prescribes both clomiphene and hCG in two distinct clinical contexts. The first is fertility-preservation: men who want to maintain sperm production while supporting healthy testosterone levels. The second is standalone testosterone optimization for men who prefer endogenous stimulation rather than exogenous supplementation, or for men who have not yet committed to long-term TRT. The right choice between exogenous testosterone, endogenous stimulation, or a combination depends on the patient's labs, goals, and preferences.

Foundational Support: What Helps Beyond a Prescription

Not every man with low-normal testosterone needs therapy immediately. Lifestyle factors meaningfully influence endogenous production. Sleep quality, body composition, resistance training, alcohol intake, and chronic stress all shape testosterone levels. Targeted nutrients can help: zinc and vitamin D deficiencies have been linked to reduced testosterone and are common in symptomatic men. Magnesium supports sleep and stress regulation, both of which feed back into hormone balance. For a deeper dive into the underlying drivers, see the VIMC Low Testosterone in Men post.

Who Is TRT For? An Individualized Approach, Not an Age Cutoff

TRT is appropriate when symptoms are present and confirmed by laboratory values. Age is treated as a clinical guide at VIMC, not a categorical limit. Younger men in their 30s or older men in their 60s and beyond can each be candidates if the workup supports it and no overt contraindications exist. For younger patients in particular, a thorough evaluation matters because low testosterone at a younger age may have a correctable underlying cause: thyroid dysfunction, pituitary issues, medication effects, opioid use, or lifestyle factors that respond to non-hormonal management.

Overt contraindications that close the door to TRT are specific: active prostate cancer, severe untreated polycythemia, severe untreated obstructive sleep apnea, and active severe cardiovascular disease. For men with these conditions, alternative hormone-balancing approaches and treatment of the underlying issue come first.

How the VIMC Team Approaches Testosterone Therapy

Male hormone care at VIMC is built on three operating principles: evaluate thoroughly, prescribe individually, and monitor continuously. The first visit anchors a full baseline picture, including free and total testosterone, DHT, estradiol, estrone, complete blood count, comprehensive metabolic panel, lipid profile, thyroid markers, and prostate health assessment with free and total PSA.

From there, prescribing is matched to the patient: which delivery method, what starting dose, whether adjunct therapies such as hCG, clomiphene, or peptides should accompany testosterone. Monitoring continues over time rather than once at initiation. Hematocrit, estrogen balance, prostate markers, and metabolic indicators are tracked on a cadence calibrated to each patient's response. Testosterone is treated as one piece of a broader hormonal and metabolic system that includes thyroid function, cardiovascular health, sleep, and nutrition.

Ready to Have a Real Conversation About TRT?

If you have been told testosterone therapy is too risky, or if you have been on TRT for years without proper monitoring, the VIMC team welcomes the conversation. The current evidence supports a more nuanced view of TRT than the headlines suggest, and a thorough, individualized approach is the difference between testosterone optimization and a prescribe-and-forget protocol.