Written by Keen Meds · Reviewed by Licensed Clinical Providers · March 1, 2026
Key Insight: The TRAVERSE sexual function sub-study (JCEM 2024) found testosterone therapy produced significantly greater improvements in sexual desire, erectile function, and overall sexual activity compared to placebo — with meaningful effect sizes sustained across the 4-year trial period.
Among all the symptoms men attribute to low testosterone, sexual changes are often the most distressing: reduced desire, difficulty with arousal, and diminished satisfaction with sexual activity. These are also, according to clinical research, the symptoms that respond most consistently and reliably to testosterone replacement therapy.
The TRAVERSE sexual function sub-study, published in the Journal of Clinical Endocrinology and Metabolism (JCEM) in 2024, provides the largest and most rigorous randomized controlled evidence base for testosterone's effects on sexual function in hypogonadal men. Here is a detailed breakdown of what the study measured, what it found, and what the findings mean clinically for men evaluating testosterone therapy.
About the Study: Design and Why It Was Done
The sexual function sub-study was led by Karol Pencina and colleagues and published in JCEM in 2024, drawing on participants from the main TRAVERSE trial.
The rationale for this sub-study was both clinical and scientific. Clinically, sexual dysfunction is the leading symptom for which men seek testosterone evaluation. Scientifically, while prior smaller trials had consistently shown sexual benefit from TRT, a large, adequately powered randomized controlled trial with extended follow-up and validated outcome measures had not previously been conducted. The TRAVERSE trial provided the scale and duration needed to establish these findings definitively.
Sexual function is inherently multi-dimensional, and the sub-study used several validated measurement instruments to capture it comprehensively.
The International Index of Erectile Function (IIEF) is the most widely used validated tool for assessing erectile function in clinical research. It measures five domains: erectile function, orgasmic function, sexual desire, intercourse satisfaction, and overall satisfaction, scored on standardized scales.
The Sexual Desire Inventory is a validated questionnaire that separately quantifies the frequency and intensity of sexual desire, since desire and erectile function can dissociate in clinical practice.
The Psychosexual Daily Questionnaire captured real-time patient-reported sexual activity, allowing tracking of actual behavior rather than retrospective recall alone.
The sub-study followed participants for up to four years, providing sustained follow-up data on whether sexual function benefits observed early in treatment persisted over the longer term.
What the Study Found
Across all primary domains measured, testosterone-treated men showed statistically and clinically significant improvements compared to placebo-treated men.
Sexual desire: the testosterone group showed substantially greater improvements in sexual desire scores on both the IIEF desire domain and the Sexual Desire Inventory. Desire is the domain most directly driven by testosterone levels, and the magnitude of improvement reflected this biological directness.
Erectile function: the testosterone group showed significantly greater improvements in IIEF erectile function domain scores compared to placebo. The effect size was meaningful by the standards used in clinical research to define clinical significance.
Sexual activity frequency: the Psychosexual Daily Questionnaire showed higher rates of sexual activity in the testosterone group compared to placebo across follow-up, consistent with the improvements in desire and erectile function.
Overall sexual satisfaction: the IIEF overall satisfaction and intercourse satisfaction domains also showed greater improvement in the testosterone group.
Crucially, these benefits were sustained across the full duration of follow-up, up to four years. This demonstrates that sexual function benefit from testosterone therapy is not simply an early placebo-influenced effect or a transient pharmacological response. The improvement is durable over the timeframe studied.
The effect sizes were also consistent across age subgroups within the 45 to 80 year age range of TRAVERSE participants, though men in the lower portion of the age range tended to show somewhat greater absolute improvements, as would be expected given potentially better baseline vascular function.
What the Critics Said: Limitations and Context
The sexual function sub-study has been well-received, but two contextual points deserve attention for an honest reading of the findings.
First, the TRAVERSE population had both confirmed hypogonadism and existing cardiovascular risk factors or pre-existing cardiovascular disease. The sexual function benefits demonstrated apply most directly to men fitting this clinical profile. Younger, healthier men with low-normal testosterone who have sexual dysfunction may or may not see the same magnitude of benefit, and the sub-study's design does not fully address this group.
Second, the distinction between libido and erectile function is clinically important even though both improved in the study. Testosterone is primarily a driver of sexual desire. Libido, or sexual motivation, is highly testosterone-sensitive and responds reliably and relatively quickly to testosterone normalization. Erectile function, by contrast, is more complex: it depends on vascular integrity (blood flow to the penis), neurological function, psychological factors, and hormonal status. Testosterone contributes to erectile function but is not the sole determinant.
Men with erectile dysfunction that is primarily vascular in origin, for example due to longstanding diabetes, hypertension, or atherosclerosis affecting penile vasculature, may see more limited erectile function improvements from testosterone alone. In these men, testosterone therapy addresses the hormonal component while other interventions may be needed to address the vascular component. The TRAVERSE sub-study's finding of significant improvement in erectile function reflects a population-level effect in which hormonal contribution was a real and addressable component for many participants.
What This Means for You Today
For hypogonadal men whose primary concerns are reduced sexual desire and diminished erectile function, the TRAVERSE sexual function sub-study provides the strongest evidence yet that testosterone therapy is an effective and durable treatment, not just an anecdotal one.
The timeline of benefit is also informative. Sexual desire and overall sexual activity improvements are among the earliest benefits observed in clinical practice with testosterone therapy. Many men report changes in desire within three to six weeks of reaching therapeutic testosterone levels. Erectile function improvements tend to follow over a somewhat longer timeline, as structural and functional changes in the relevant tissue take time to manifest.
What the research makes clear is that low testosterone is a meaningful and addressable contributor to sexual dysfunction in hypogonadal men, and that addressing it through replacement therapy produces consistent, sustained improvement in the domain that most commonly motivates men to seek evaluation in the first place.
For men whose sexual dysfunction is multifactorial, testosterone therapy can be combined with other evidence-based approaches. Clinical evaluation should identify which components of sexual dysfunction are hormonally driven and which may require additional treatment. A comprehensive evaluation is a starting point, not a guarantee of a single-solution answer.
Frequently Asked Questions
How quickly does testosterone therapy improve sexual desire?
Sexual desire is often one of the earliest benefits of testosterone therapy. Many men report improvements in desire within three to six weeks of reaching therapeutic testosterone levels. Full benefit typically develops over three to six months as levels stabilize in the mid-normal physiological range. The TRAVERSE sub-study showed these benefits sustained over up to four years.
Does testosterone therapy treat erectile dysfunction?
Testosterone therapy significantly improved erectile function in the TRAVERSE sexual function sub-study, and this is consistent with evidence across multiple prior trials. However, erectile function is multi-determined: vascular health, neurological function, and psychological factors all contribute. Testosterone addresses the hormonal component. Men with erectile dysfunction that is primarily vascular or neurological in cause may see more limited improvement from testosterone alone and may benefit from additional evaluation and treatment.
What is the IIEF and how is it used to measure erectile function?
The International Index of Erectile Function (IIEF) is the most widely validated and used instrument for measuring erectile function in clinical research. It includes five domains: erectile function, orgasmic function, sexual desire, intercourse satisfaction, and overall sexual satisfaction, each scored on standardized scales. It allows researchers to compare sexual function outcomes across groups in a consistent, validated way.
Does testosterone therapy improve sexual function in men over 60?
The TRAVERSE sub-study included men from 45 to 80 years of age and demonstrated significant improvements in sexual function across the age range. Men in older age groups showed real improvements, though absolute effect sizes varied. Age-related vascular and neurological changes can limit the extent to which testosterone therapy alone fully restores erectile function in older men, but hormonal contribution remains meaningful and addressable.
What the Research Means for Your Treatment Options
Sexual dysfunction is the most consistently reported and most consistently responsive symptom domain in testosterone therapy research. The TRAVERSE sexual function sub-study confirms what clinical experience and smaller trials have suggested for years: testosterone therapy produces meaningful, sustained improvements in sexual desire, erectile function, and sexual activity in hypogonadal men. For men whose low testosterone is contributing to sexual dysfunction, treating the underlying deficiency addresses the problem at its hormonal root.
Keen Meds connects you with licensed clinical providers for a telehealth evaluation and lab review. If your testosterone is clinically low, you may qualify for Testosterone Spray Rx, a needle-free transdermal testosterone program.
