Ashwagandha (Withania somnifera) is a medicinal plant that has been used in Ayurvedic medicine for over 3,000 years. In traditional practice, it was valued as a rasayana - a class of herbs believed to promote vitality, longevity, and resilience.

Modern research has validated much of that traditional use. The plant's primary bioactive compounds - withanolides, steroidal lactones concentrated in the root, are responsible for most of its measurable physiological effects.

In clinical research, ashwagandha is classified as an adaptogen: a compound that helps the body regulate its response to physical and psychological stress. Unlike stimulants, which force a stress response, adaptogens modulate the body's stress systems - helping to bring an overactivated stress response down, or support an exhausted one, depending on what the individual needs.

This bi-directional modulation is important, and we'll come back to it.

The claim that ashwagandha "binds to oestrogen receptors" and may interfere with HRT circulates fairly widely online, usually without citing the specific research it's based on.

Here is what the research actually shows.

Certain withanolides - specifically withaferin A, one of several active compounds in ashwagandha - have been studied for effects on oestrogen receptor alpha (ERα) expression in breast cancer cell lines in laboratory settings. One study (Hahm et al., 2011, Molecular Carcinogenesis) found that withaferin A suppressed ERα expression in human breast cancer cells in vitro.

This is where the "ashwagandha blocks oestrogen" claim originates.

However, there are several critical reasons why this does not translate straightforwardly to women taking HRT:

A comprehensive systematic review published in late 2025 (Phytotherapy Research, Wiley) that evaluated ashwagandha's hormonal effects across preclinical, clinical, and case study evidence concluded that multiple studies consistently show ashwagandha-mediated reductions in cortisol - supporting its proposed anti-stress effects via HPA axis modulation. The evidence for direct oestrogenic activity in humans remains limited and inconsistent.

The honest scientific position is this: for most women taking standard HRT at therapeutic doses, there is no current strong clinical evidence that ashwagandha interferes with oestrogen receptors or competes with exogenous hormones. That said, if you are on HRT or any prescription hormone therapy, speaking with your prescribing doctor before adding any supplement is always the right approach - because individual circumstances, medications, and health histories vary.

Here is what I find genuinely fascinating about this topic.

Perimenopause is typically framed as a hormone story. Oestrogen declines. Progesterone becomes erratic. The menstrual cycle shifts. Hot flushes arrive.

But the lived experience of perimenopause is often described in a different set of words: I don't feel like myself. My sleep has changed. Small things feel huge. I'm more anxious than I used to be. I'm exhausted but I can't switch off.

These are not just hormone symptoms. They are nervous system and stress system symptoms - and understanding why requires looking at how the stress response and the reproductive hormone system are connected.

The HPA Axis and Perimenopause

The HPA axis - the hypothalamic-pituitary-adrenal axis - is the body's central stress management system. When you experience a stressor, the hypothalamus releases CRH (corticotropin-releasing hormone), which signals the pituitary to release ACTH (adrenocorticotropic hormone), which in turn signals the adrenal glands to produce cortisol.

In normal circumstances, this is an elegantly calibrated system. Cortisol rises to manage the stressor and then falls as a negative feedback loop engages - the hypothalamus and pituitary sense adequate cortisol and signal the adrenals to stand down.

During perimenopause, this system becomes dysregulated - and the reason is directly hormonal.

Oestrogen plays a significant role in regulating glucocorticoid receptor sensitivity in the brain. As oestrogen levels decline and fluctuate during the perimenopausal transition, the HPA axis becomes more reactive - the stress response threshold lowers, cortisol is produced more readily, and the feedback mechanism that should turn it off becomes less efficient.

This is why so many women describe feeling "wired but tired" in perimenopause: their stress response system is running hotter than it used to, even when nothing externally has changed.

And elevated cortisol doesn't stay in its lane. It interacts with almost every other system in the body:

• Elevated cortisol disrupts sleep architecture, reducing deep restorative sleep
• Poor sleep raises cortisol further - creating a reinforcing loop
• Chronically elevated cortisol drives systemic inflammation
• Inflammation accelerates cellular ageing and compounds the fatigue already present
• Cortisol competes with progesterone for receptor sites, potentially amplifying hormonal imbalance symptoms

This is not a peripheral issue. For many women in perimenopause, chronic stress load and HPA axis dysregulation sit at the centre of the symptoms they are experiencing - and HRT, which addresses the oestrogen and progesterone decline, does not directly modulate the stress response.

This is where ashwagandha becomes relevant.

The research on ashwagandha in perimenopausal and menopausal women has expanded significantly in the last few years.

Stress and cortisol: A 2024 meta-analysis examining seven randomised controlled trials (488 participants) found that ashwagandha supplementation produced significant reductions in both serum cortisol and perceived stress scores compared to placebo. The effect was most pronounced in individuals with elevated baseline stress - which describes many women in the perimenopausal transition. Withanolides appear to modulate HPA axis activity by restoring glucocorticoid receptor sensitivity in the hypothalamus and pituitary, improving the efficiency of the feedback loop that regulates cortisol.

Sleep quality: Multiple RCTs have demonstrated improvements in sleep quality, sleep onset, and sleep duration with ashwagandha supplementation. A double-blind trial examining 300 mg of KSM-66 twice daily found a 69% improvement in overall sleep quality score, alongside reductions in the time taken to fall asleep and in nighttime awakenings. This is clinically meaningful for perimenopausal women, for whom sleep disruption is one of the most commonly reported and functionally impairing symptoms.

Perimenopausal symptoms specifically: The landmark randomised controlled trial by Gopal et al. (2021) found that 300 mg of ashwagandha root extract twice daily for eight weeks in perimenopausal women produced significant reductions in Menopause Rating Scale (MRS) scores - including improvements in hot flushes, sleep, irritability, anxiety, and mood - compared to placebo. A further 2026 study published in Frontiers in Reproductive Health (Vani et al., 2026) examined ashwagandha root extract in perimenopausal women over twelve weeks, again finding significant symptom improvements and a favourable safety profile.

Sexual function and wellbeing: Dongre et al. found that ashwagandha root extract enhanced sexual function, sexual arousal, lubrication, and reduced sexual distress in healthy women - a dimension of perimenopausal wellbeing that is frequently overlooked.

It is worth noting that ashwagandha is not a hormonal treatment. It does not replace oestrogen or progesterone. Its benefits during perimenopause appear to operate through the stress and nervous system pathways - reducing the cortisol-driven amplification of symptoms - rather than through direct hormonal correction.

For women on HRT, this matters. HRT addresses the hormonal side of the equation. Ashwagandha addresses the stress and nervous system side. For many women, both layers are active simultaneously.

One of the most important things studying biochemistry taught me is that the body does not operate in separate compartments.

Every system influences another. Hormones influence the nervous system. The nervous system influences sleep. Sleep influences cortisol. Cortisol influences inflammation. Inflammation influences energy, mood, cognition, and joint health.

When I describe this to customers, I often use the image of a mobile - one of those hanging structures where each element is balanced relative to all the others. If you push one piece, everything else shifts. And if you only address one piece, the rest of the mobile remains off-balance.

Perimenopause moves many pieces of the mobile at once. HRT can rebalance the hormonal piece. But the sleep piece, the cortisol piece, the inflammation piece, the energy piece - those often need support too.

Small improvements in one area create ripple effects throughout the system:

• Support sleep, and stress resilience often improves
• Reduce cortisol, and sleep quality often improves
• Improve both, and energy, mood, and cognitive clarity tend to follow

This is why I chose to include ashwagandha in Healthspan. Its role is not to replace HRT or to act as a hormone. Its role is to support stress resilience, cortisol regulation, and restorative sleep - three areas that many women find become more challenging during perimenopause, and that influence everything else.

Not all ashwagandha supplements are equivalent, and this matters particularly in the context of HRT.

The clinical research is conducted almost exclusively using standardised root extracts - primarily KSM-66 (standardised to ≥5% withanolides from root only) and Sensoril (standardised from root and leaf). Products using unstandardised root powder or proprietary blends without disclosed withanolide percentages have unpredictable active compound content.

Doses in clinical trials for stress and perimenopausal symptoms range from 300–600 mg of standardised extract daily. Higher doses are not necessarily better, and there is a published 2026 case report in Endocrinology, Diabetes & Metabolism Case Reports describing HPA axis suppression in a patient using chronically high, non-standardised doses - a reminder that therapeutic compounds require appropriate dosing, not maximised dosing.

The form also matters. Root-only extracts have a different and better-characterised safety profile than leaf-containing preparations, particularly for long-term use.

If you are taking HRT, prescription medications, or managing a health condition, please speak with your doctor, pharmacist, or qualified healthcare practitioner before introducing ashwagandha or any new supplement into your routine.

This is not a disclaimer added for legal reasons. It is genuine advice from someone who believes in both the power of plant-based support and the importance of individualised medical care.

Your prescribing doctor knows your full health history, your current medication profile, and the specific type of HRT you are taking. That context matters for any decision about supplementation - and a five-minute conversation can save a great deal of uncertainty.

What I can offer is the science - clearly, honestly, and without overstatement. The research suggests that for most healthy perimenopausal women, standardised ashwagandha root extract at appropriate doses is well-tolerated and may provide meaningful support for the stress, sleep, and nervous system challenges that accompany the hormonal transition. Whether that is right for you is a conversation worth having with someone who knows your individual circumstances.

• Gopal S et al. (2021). Effect of an ashwagandha root extract on climacteric symptoms in women during perimenopause: a randomized, double-blind, placebo-controlled study. Journal of Obstetrics and Gynaecology Research, 47(12), 4414–4425.

• Vani I, Muralidhar G, Rao BS. (2026). A prospective, randomized, double-blind, placebo-controlled study on efficacy and safety of Ashwagandha root extract (Withania somnifera) for managing menopausal symptoms in women. Frontiers in Reproductive Health, 7:1647721.

• Hahm ER et al. (2011). Withaferin A suppresses estrogen receptor-α expression in human breast cancer cells. Molecular Carcinogenesis, 50(8), 614–624.

• Chandrasekhar K et al. (2012). A prospective, randomized double-blind, placebo-controlled study of safety and efficacy of a high-concentration full-spectrum extract of Ashwagandha root in reducing stress and anxiety in adults. Indian Journal of Psychological Medicine, 34(3), 255–262.

• Evaluation of Potential Hormonal Activities of Ashwagandha (Withania somnifera). (2025). Phytotherapy Research, Wiley Online Library.

• Dongre S et al. (2015). Efficacy and safety of Ashwagandha root extract in improving sexual function in women: a pilot study. BioMed Research International.