If we analyze the currently human clinical trial data, the findings suggest that dose matters within a given extract, but the overall literature is insufficient to define generalizable, condition-specific dose–response rules across products. Most trials test a single dose versus placebo, which limits inference beyond “this dose worked in this population” (Lopresti & Smith, 2021). I’ll review those findings briefly in today’s post and then reframe the analysis with the hope of uncovering more useful strategies for dosing next time.
Stress, Anxiety and Insomnia
The only domain with credible dose-comparison evidence is for treatment of stress and anxiety. In a randomized controlled trial comparing 125 mg twice daily versus 300 mg twice daily of the same root extract over 8 weeks, both doses reduced perceived stress and cortisol relative to placebo, but anxiety severity (HAM-A) showed clearer separation from placebo at the higher dose, indicating a threshold or steeper dose–response for anxiety outcomes (Salve et al., 2019). Other trials demonstrate efficacy at much lower nominal doses, but only when using highly concentrated extracts with different withanolide standardization, confirming that milligram dose alone is not a transferable metric across products (Mishra & Kumar, 2024). A recent meta-analysis focusing on stress outcomes found a significant pooled reduction in cortisol but inconsistent effects on subjective stress scales, explicitly identifying limitations based on dose standardization and extract comparability (Albalawi, 2025).
Insomnia and non-restorative sleep trials show benefit at both moderate doses (e.g., 300 mg twice daily) and lower daily doses using more concentrated extracts. However, there are no rigorous dose-ranging sleep trials, so improvement at multiple doses cannot be interpreted as equivalence or optimization (Langade et al., 2019; Deshpande et al., 2020). A placebo-controlled trial using 300 mg twice daily for 8 weeks in chronically stressed adults showed improvements in perceived stress, cortisol, and weight-related measures. No lower- or higher-dose comparators were tested (Choudhary et al., 2017b).
In generalized anxiety disorder, a randomized double-blind placebo-controlled trial using 500 mg/day of Withania somnifera root extract (250 mg twice daily) for 6 weeks supports anxiolytic effects at the studied dose GAD (Fuladi et al., 2021).
Cognitive Performance
Additional clinical evidence shows that a sustained-release standardized root extract at 300 mg taken daily for 90 days improved cognitive-related outcomes in stressed adults (Gopukumar et al., 2021).
Short-term psychomotor/cognitive testing in healthy men used 1,000 mg/day (250 mg × 2 capsules twice daily) of a dried aqueous extract (roots + leaves) for 14 days in a crossover design reported measurable effects at a fixed daily dose (Pingali et al., 2014). In adults with mild cognitive impairment, 600 mg/day (300 mg twice daily) for 8 weeks improved multiple memory subtests and executive/attention measures versus placebo; again, the design supports “this dose worked,” not optimization or a threshold model (Choudhary et al., 2017a).
In obsessive-compulsive disorder, a randomized double-blind placebo-controlled adjunctive trial using 120 mg/day of root extract (60 mg twice daily) for 6 weeks alongside SSRI therapy reported benefit at the studied dose (Jahanbakhsh et al., 2016).
Adjunctive use of ashwaganhda has been tested in schizophrenia in a randomized double-blind placebo-controlled pilot trial using 1,000 mg/day of powdered root (500 mg twice daily) for 12 weeks, showing movement in symptom measures versus placebo but without dose-response structure (Agnihotri et al., 2013; Chengappa et al., 2018).
Physical performance and hormonal dysregulation
Several athlete/strength outcomes trials use ~600 mg/day for ~8 weeks and report improvements in strength, endurance, or recovery markers versus placebo, but do not include alternative dose arms; this supports efficacy-at-dose but not dose optimization (Tiwari et al., 2021; Wankhede et al., 2015; Ziegenfuss et al., 2018). A meta-analysis of physical performance reports overall benefit (Bonilla et al., 2021). A comprehensive systematic review of human trials concludes that heterogeneity in extract type, dose, and duration prevents strong dose-specific conclusions, even where efficacy signals are consistent (Lopresti & Smith, 2021).
In healthy women with sexual dysfunction criteria, 600 mg/day (300 mg twice daily) for 8 weeks improved validated sexual function/distress measures versus placebo (Ajgaonkar et al., 2022). In perimenopausal women with climacteric symptoms, 600 mg/day (300 mg twice daily) for 8 weeks reduced menopause rating scale scores and improved menopause-related quality-of-life domains versus placebo, with concurrent hormonal parameter shifts reported (Gopal et al., 2021).
In a safety RCT in healthy adults used 600 mg/day (300 mg twice daily) for 8 weeks and explicitly monitored thyroid function along with hematology/chemistry, supporting that this dose has been prospectively evaluated for short-term safety in a controlled setting (Verma et al., 2021). In subclinical hypothyroidism, a placebo-controlled trial reports thyroid index changes with ashwagandha (Sharma et al., 2018).
Across indications, dosing “matters” in the limited sense that specific regimens (often 600 mg/day, sometimes 1,000 mg/day, sometimes lower mg with concentrated extracts) repeatedly produce measurable effects in RCTs. Endocrine/biomarker shifts also indicate physiologic impact at common doses (Choudhary et al., 2017; Pingali et al., 2014; Sharma et al., 2018; Verma et al., 2021).
The evidence remains insufficient to define condition-specific dose–response rules because:
Most trials test one dose
Extracts differ materially in withanolide composition and standardization
Milligram dose is not a transferable metric across extract systems
Systematic reviews and stress-focused meta-analyses simply mirror these limitations (Albalawi, 2025; Lopresti & Smith, 2021). Next time we’ll explore other ways to think about dose.
References
Agnihotri, A. P., Sontakke, S. D., Thawani, V. R., Saoji, A., & Goswami, V. S. S. (2013). Effects of Withania somnifera in patients of schizophrenia: A randomized, double blind, placebo controlled pilot trial study. Indian Journal of Pharmacology, 45(4), 417–418. https://doi.org/10.4103/0253-7613.115012
Ajgaonkar, A., Jain, M., & Debnath, K. (2022). Efficacy and safety of Ashwagandha (Withania somnifera) root extract for improvement of sexual health in healthy women: A prospective, randomized, placebo-controlled study. Cureus, 14(10), e30787. https://doi.org/10.7759/cureus.30787
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