She had been on estrogen for two years and had done everything right. Her hot flashes were gone. Her sleep had stabilized. On paper, her hormone therapy was working.
But something was still missing. The drive she used to have — in her work, in her workouts, in her relationship — hadn't come back with the estrogen. Her body composition continued to shift in ways she couldn't explain. Some days, her mind felt like it was operating at three-quarter speed.
"I thought estrogen was supposed to fix this," she said. "Why don't I feel like myself yet?"
The answer is one that conventional hormone therapy has been slow to integrate into practice: estrogen and testosterone are not interchangeable. They do not address the same systems. They do not carry the same risks. And for many perimenopausal women, treating one without investigating the other leaves the most disruptive symptoms unaddressed.
Two Hormones. Two Different Conversations.
The tendency to think of "hormone therapy" as a single treatment — a category rather than a spectrum — is one of the most persistent sources of confusion in women's health. When most providers and patients talk about hormone therapy, they mean estrogen. Estrogen is FDA-approved, guideline-supported, and well-studied. It does specific, important things. But it is not the whole picture.
Estrogen
Primary decline in late perimenopause & menopause
- Vasomotor regulation (hot flashes, night sweats)
- Bone density maintenance
- Vaginal and urogenital tissue health
- Cardiovascular lipid metabolism
- Mood stability via serotonin modulation
- Moderate–severe vasomotor symptoms
- Genitourinary syndrome of menopause
- Osteoporosis prevention
Testosterone
Gradual decline beginning in the mid-thirties
- Libido and sexual motivation
- Energy, motivation, and drive
- Muscle synthesis and body composition
- Cognitive sharpness and focus
- Bone density (independent pathway)
- Hypoactive sexual desire disorder (HSDD)
- Energy & wellbeing in symptomatic women
- Body composition support
This distinction matters enormously in practice. A woman whose primary complaints are fatigue, low drive, cognitive slowness, and body composition changes is describing a largely testosterone-mediated picture. Estrogen may support her mood and protect her bones. But if testosterone is not assessed and addressed, the symptoms she finds most disruptive are unlikely to resolve — regardless of how optimized her estrogen is.
Why Timing Changes Everything for Estrogen
One of the most important and least-communicated realities of hormone therapy is that its risk-benefit profile is not static. It changes meaningfully depending on when it is initiated relative to menopause — a concept now supported by decades of research and enshrined in the guidelines of every major menopause society.
This is called the timing hypothesis — or more recently, the critical window — and it reframes how we should think about who benefits most from estrogen therapy and who faces elevated risk.
The Women's Health Initiative — the large study that frightened a generation of women and providers away from hormone therapy — enrolled women with an average age of 63. Many were more than a decade past menopause. The risks observed in that population, it is now understood, do not apply cleanly to women initiating therapy in their late forties or early fifties.
Perimenopause is not just the moment when hormone therapy is most likely to relieve symptoms. It is the moment when it is most likely to protect long-term cardiovascular, neurological, and skeletal health — with the most favorable risk profile of any window in a woman's life.
The critical window is not a marketing concept. It is a biological reality grounded in vascular biology, neurological timing, and decades of outcomes data. Starting earlier — in the right candidate — is not aggressive. It is evidence-based.
What the Evidence Actually Shows for Testosterone
Here is where the original framing many women receive — that testosterone has no proven benefit beyond sexual desire — deserves direct correction. The evidence has matured significantly, and the picture is more nuanced than a single indication.
[1] Davis SR, et al. Global Consensus Position Statement on the Use of Testosterone Therapy for Women. J Clin Endocrinol Metab. 2019;104(10):4660–4666.
[2] Islam RM, et al. Safety and efficacy of testosterone for women: a systematic review and meta-analysis. Lancet Diabetes Endocrinol. 2019;7(10):754–766.
[3] Parish SJ, et al. ISSWSH Process of Care for the Identification and Management of HSDD in Premenopausal Women. Mayo Clin Proc. 2019;94(5):842–861.
[4] Huang G, et al. Testosterone dose-response relationships in hysterectomized women with or without oophorectomy. J Clin Endocrinol Metab. 2014;99(5):1823–1830.
[5] Davison SL, et al. Testosterone improves verbal learning and memory in postmenopausal women. Maturitas. 2011;70(3):307–311.
[6] Shifren JL, et al. Transdermal testosterone treatment in women with impaired sexual function after oophorectomy. NEJM. 2000;343(10):682–688.
What the evidence does not support is the claim that testosterone has no role beyond libido. That framing reflects a 2014 reading of the literature, not a 2024 one. The field has moved.
On Safety — What We Know and What We're Still Learning
Testosterone therapy in women is not without considerations. At physiologic doses — the levels that restore what a woman's body naturally produced at a younger age rather than elevating beyond it — the safety profile is reassuring. The concerns that exist are real but largely dose-dependent and reversible.
Acne and increased hair growth are the most common side effects and typically indicate supraphysiologic dosing. They are generally reversible with dose reduction and are a signal to adjust rather than discontinue.
Cardiovascular effects at oral doses are a legitimate concern — oral testosterone affects lipid metabolism unfavorably. Transdermal and subcutaneous routes largely avoid this effect, which is why route of administration matters.
Long-term safety data beyond 24 months remains a genuine limitation of the evidence base. This does not mean long-term use is unsafe — it means ongoing monitoring and periodic reassessment are part of responsible prescribing.
Breast cancer risk at physiologic doses has not been demonstrated to increase in current evidence. Testosterone may in fact be weakly protective via aromatase inhibition, though this area requires more data before strong conclusions can be drawn.
The goal is restoration, not amplification. Returning testosterone to the physiologic range a woman experienced in her thirties is categorically different from masculinizing doses — in mechanism, in risk, and in clinical intent.
What This Means If You're in Perimenopause
If you are between 45 and 55 and experiencing the convergence of symptoms that characterize perimenopause — disrupted sleep, vasomotor instability, shifting body composition, cognitive changes, low drive, fatigue that doesn't resolve with rest — you are sitting in the most favorable window of your hormonal life to intervene thoughtfully.
The question is not whether to treat. The question is which hormones are relevant to your specific symptom picture, what your individual risk profile looks like, and what the appropriate sequencing and formulation of therapy should be for you — not for the average woman in a clinical trial cohort.
Estrogen and testosterone are not competing therapies. They are complementary tools that address different systems. For many women in perimenopause, both warrant evaluation. For most, treating only one while ignoring the other leaves something significant on the table.
The woman who opened this post — two years on estrogen, still not feeling like herself — wasn't a treatment failure. She was an incomplete evaluation. When testosterone was assessed, a clear deficiency was found. When it was addressed alongside her estrogen, the picture that had been stubbornly incomplete finally resolved.
"This is what I was waiting for," she said at her follow-up. "I just didn't know I was waiting for this."
A complete hormonal evaluation starts here.
At Mercure, we evaluate estrogen, testosterone, SHBG, and the full metabolic picture — because perimenopausal symptoms rarely have a single-hormone answer. Your evaluation is designed for you specifically.
Book a ConsultationClinical References
¹ Davis SR, et al. Global Consensus Position Statement on the Use of Testosterone Therapy for Women. J Clin Endocrinol Metab. 2019;104(10):4660–4666.
² Manson JE, et al. Menopausal Hormone Therapy and Long-term All-Cause and Cause-Specific Mortality. JAMA. 2017;318(10):927–938.
³ Hodis HN, Mack WJ. A "Window of Opportunity:" The Reduction of Coronary Heart Disease and Total Mortality with Menopausal Therapies Is Age- and Time-Dependent. Brain Res. 2011;1379:244–252.
⁴ Islam RM, et al. Safety and efficacy of testosterone for women: a systematic review and meta-analysis of randomised controlled trial data. Lancet Diabetes Endocrinol. 2019;7(10):754–766.
⁵ Shifren JL. Testosterone for Midlife Women: The Right Time, Right Dose. Menopause. 2021;28(7):703–706.
⁶ Baber RJ, et al. IMS Recommendations on women's midlife health and menopause hormone therapy. Climacteric. 2016;19(2):109–150.
