The Overlooked Hormone: Why Testosterone Matters for Both Him and Her

Filed under "male hormone" for decades, testosterone is now understood as essential to reproductive and metabolic health in women too just at a fraction of the concentration, and with its own distinct clinical picture.

Ask most people what testosterone does, and the answer will centre on men muscle, libido, drive. That picture is incomplete on both sides. In men, testosterone's reach extends well past sexual function into bone density, cardiovascular health, mood regulation and sperm production. In women, it is not a trace hormone or a side effect of male physiology; it is produced deliberately by the ovaries and adrenal glands, and it plays a direct role in ovarian follicle growth, fertility, cognition and bone metabolism.

The clinical and research communities have spent the last several years correcting course on this. Here is what the current evidence actually shows  for men, for women, and for the growing number of couples navigating fertility together.

Testosterone in Male Physiology

Testosterone is the defining hormone of male reproductive physiology, but its role extends across nearly every system in the body. A 2025 systematic review in Cureus describes it as a hormone that plays a complicated and significant role in men's physiology driving the development and maintenance of muscular mass, bone density and general physical strength, while also directly affecting spermatogenesis, libido and erectile function.

Rojas-Zambrano et al., Cureus, 2025

Clinical literature increasingly frames testosterone as a central regulator of long-term male health rather than a single-function hormone. Maintaining optimal levels in later life is linked to reduced risk of osteoporosis, metabolic disorders and cardiovascular disease, alongside its more familiar roles in energy, mood and fertility.

Yassin et al., UroPrecision, 2025

The Fertility Connection

For men actively trying to conceive, testosterone's role in spermatogenesis the process of sperm production makes it directly relevant to fertility outcomes, not just to libido or performance. This is one reason male reproductive health has become a more prominent part of the fertility conversation generally, rather than being treated as secondary to female fertility.

Testosterone in Female Physiology

The female picture has undergone a more significant research shift. A 2025 cross-sectional study of over 8,000 women, published in eBioMedicine, states directly that testosterone is physiologically important for ovarian function, specifically for growing ovarian follicles and hence for fertility. During the reproductive years, roughly half of circulating testosterone originates in the ovaries themselves, with the remainder synthesised from adrenal pre-androgens a balance that shifts once ovarian function declines at menopause.

Wang et al., eBioMedicine, 2025

This is not a new finding so much as a recently mainstreamed one. Androgens, including testosterone, have long been understood to contribute to ovarian function, sexual function, bone metabolism and cognition across the female reproductive lifespan but research on female androgen deficiency has historically lagged far behind research on excess (as seen in conditions like PCOS/PMOS).

Benetti-Pinto, 2022

Mood, Cognition and Midlife

The most compelling recent data comes from perimenopause and menopause research. A 2024 observational study of over 500 women at a specialist English menopause clinic looked at patients already on hormone replacement therapy who continued to experience low mood, brain fog and reduced libido. After low-dose testosterone was introduced alongside their existing HRT, nearly half reported improved mood, and substantial proportions reported sharper cognitive clarity and increased libido.

Archives of Women's Mental Health, 2024

This aligns with the position taken by both the International Menopause Society and the Endocrine Society, which support testosterone use in postmenopausal women experiencing persistent sexual dysfunction, provided dosing is carefully monitored.

Where the Evidence Gets More Cautious

Editorial honesty matters here, because not every recent finding points in the same direction. A 2025 secondary analysis of a randomised controlled trial, published in Human Reproduction, found that transdermal testosterone did not improve fertility-related quality of life compared with placebo in women with diminished ovarian reserve undergoing a nine-week, low-dose protocol.

Leathersich et al., Human Reproduction, 2025

Similarly, a 2025 review in Gynecological Endocrinology examining testosterone as an IVF adjuvant for low responders described the evidence as still contested, with a 2024 Cochrane review of androgen supplementation in assisted reproduction reaching mixed conclusions depending on the outcome measured.

Kolibianakis, Gynecological Endocrinology, 2025; Naik et al., Cochrane Database of Systematic Reviews, 2024

The Bigger Picture

What the last few years of research have clarified is this: testosterone is not a male hormone that occasionally shows up in women, nor a female hormone borrowed by men. It is a hormone with genuine, sex-specific physiological necessity on both sides supporting fertility, mood, cognition and long-term metabolic health differently in each, but meaningfully in both. The nuance matters more than the headline. Emerging benefit data is real, but so are the open questions, and the responsible approach sits between the two: support the body's natural hormonal foundations, and treat clinical intervention as a conversation to have with a doctor, not a shortcut to take alone.