Ashwagandha (KSM-66)

What is ashwagandha (KSM-66)?

Ashwagandha (Withania somnifera) is an adaptogenic herb used in Ayurveda for over 3,000 years. The plant contains a family of steroidal lactones called withanolides, which are believed to drive much of its biological activity. "KSM-66" refers to a specific patented extract developed by Ixoreal Biomed, made from root only (not leaf), standardized to a minimum of 5% withanolides by HPLC, and produced via a green-chemistry water-based extraction.

Most well-designed human trials of ashwagandha in the last 15 years used KSM-66 or Sensoril (a different leaf-and-root extract) — which is why the form matters: results from one extract do not automatically transfer to another.

How ashwagandha works

Ashwagandha's primary mechanism is HPA-axis modulation — it dampens the hypothalamic-pituitary-adrenal pathway that drives cortisol output in response to stress. It is not a sedative; it does not bind GABA receptors directly. Instead, it lowers the baseline tone of the stress system, which is why it shows effects on cortisol, perceived stress, and sleep onset without producing daytime grogginess.

Secondary effects observed in trials include modest improvements in thyroid hormone output, testosterone in men, and VO2max — all consistent with HPA-axis recovery rather than direct hormonal action.

What the evidence shows

• A 2012 randomized double-blind trial in Indian J Psychological Medicine found that 300 mg of KSM-66 twice daily reduced serum cortisol by 27.9% versus 7.9% in placebo, alongside significant reductions in perceived stress and DASS-42 scores [1].
• A 2019 trial in Medicine (Baltimore) found 240 mg/day of KSM-66 over 8 weeks significantly reduced anxiety and morning cortisol [2].
• A 2020 randomized trial in Cureus showed improvements in sleep quality (PSQI) and sleep onset latency at 600 mg/day over 8 weeks [3].

Evidence level: strong for cortisol, perceived stress, and sleep quality at the doses studied.

Ashwagandha for menopause and women over 40

The midlife stress profile is distinctive: estradiol withdrawal removes a normal brake on the HPA axis, cortisol rhythms flatten, and women report a specific pattern of wired-but-tired symptoms — 3am wakings, racing mind at night, blunted morning energy. This is the exact phenotype ashwagandha addresses.

A small but specifically relevant 2021 trial in perimenopausal women using 300 mg of KSM-66 twice daily for 8 weeks found significant improvements in menopause-specific quality-of-life scores, total Menopause Rating Scale, hot-flash frequency, and serum estradiol and FSH compared with placebo. The hormonal changes are modest and likely downstream of HPA-axis recovery rather than direct estrogen-receptor activity.

For women on HRT, ashwagandha can be a useful adjunct for the residual stress, sleep, and cognitive symptoms that hormone replacement does not fully resolve. It also pairs well with magnesium L-threonate for sleep onset.

Dosage used in research

The most consistent results have come from 300 mg of KSM-66, twice daily, for at least 8 weeks (600 mg/day total). Lower doses (240 mg/day) also show benefit. Effects on perceived stress appear within 2–4 weeks; cortisol and sleep effects build through week 8. Discuss dosing with your provider, especially if you take thyroid medication.

Safety and interactions

Ashwagandha is generally well tolerated. The most common side effects are mild GI discomfort and, rarely, drowsiness at higher doses. It may modestly increase thyroid hormone output, which means women on levothyroxine should have TSH rechecked within 6–8 weeks of starting.

Ashwagandha should not be used during pregnancy (traditional emmenagogue), in autoimmune thyroid disease without supervision, or with strong immunosuppressants. Case reports of liver injury exist but are rare and generally associated with combination products containing other extracts.

Where you will find it at kindr

KSM-66 ashwagandha is the active in our Cortisol Balance formulation and a frequent recommendation in our broader menopause supplements guide.

Medically reviewed by Dr. Ana Lisa Carr, MD, MBA
Board-Certified Family Medicine Physician · Lead Provider / Medical Reviewer
NPI 1689841744 · Last reviewed: May 10, 2026