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Does ashwagandha reduce cortisol and anxiety?

Trials show standardized ashwagandha extracts modestly reduce anxiety and cortisol, but small sample sizes, study flaws, and rare liver risks warrant caution.

Published October 2026

Short answer

Moderate evidence shows standardized ashwagandha extracts lower anxiety scores and cortisol. Most trials are small and short-term, however, and rare cases of liver injury have been reported. Evidence grade B (Moderate). Meta-analyses of randomised controlled trials show reductions in anxiety scores and cortisol; downgraded for high heterogeneity, small trial sizes, and cortisol being a surrogate marker.

Key takeaways

  • Across meta-analyses of randomised trials, standardized ashwagandha extracts significantly lowered anxiety and stress scores compared with placebo [1] [2].
  • Pooled trials found that ashwagandha reduced morning cortisol levels, though one 2025 review noted this drop did not always match improvements in perceived stress [2] [3].
  • In a meta-analysis of five trials, ashwagandha also modestly improved sleep quality, with greater benefits seen in people with insomnia taking at least 600 mg daily [4].
  • Most trials used 240 to 600 mg daily of standardized root extract for 6 to 12 weeks, with mild digestive upset being the most common side effect [5] [6].
  • Case series in North America, Europe, and India have linked ashwagandha supplements to rare acute liver injury, which proved fatal in three patients with pre-existing liver disease [7] [8].

The short version

Taking standardized Ashwagandha root extract appears to modestly reduce anxiety and lower cortisol levels in stressed adults [1] [2]. However, the trials are mostly small, short, and show substantial variation in results [1] [3]. Furthermore, rare cases of severe liver injury have emerged, meaning it is not suitable for everyone [7] [8].

What the studies show

Anxiety and stress. A 2022 systematic review and meta-analysis of 12 randomised controlled trials with 1,002 participants found that ashwagandha extract significantly reduced anxiety and stress scores compared with placebo [1]. A 2024 meta-analysis pooling nine trials with 558 participants similarly showed significant improvements on the Perceived Stress Scale and the Hamilton Anxiety Rating Scale [2]. A 2024 meta-analysis focusing on five trials with 254 participants also reported a significant drop in Hamilton Anxiety Rating Scale scores [9]. Furthermore, a 2026 systematic review of 22 studies reported overall improvements in stress and anxiety, but noted that high heterogeneity and study design differences limit firm conclusions [10].

Cortisol reduction. Cortisol is a hormone released by the adrenal glands during stress. In the 2024 meta-analysis of nine trials, ashwagandha supplementation reduced serum cortisol by an average of 2.58 micrograms per decilitre compared with placebo [2]. A 2025 meta-analysis pooling seven randomised trials with 488 participants confirmed a significant drop in serum cortisol of 1.16 micrograms per decilitre [3]. A 2023 systematic review of nine human trials also concluded that brief-term ashwagandha supplementation decreases cortisol secretion [11]. In individual clinical trials, an eight-week study using 240 mg daily of standardized extract showed a significant reduction in morning cortisol [5], and a 60-day trial using 600 mg daily reported a 27.9% reduction in serum cortisol compared with 7.9% in the placebo group [6].

Sleep quality. Because stress often disrupts sleep, several trials have evaluated sleep outcomes. A 2021 meta-analysis of five randomised controlled trials with 400 participants found that ashwagandha produced a small but significant improvement in overall sleep quality [4]. The sleep benefit was clearest in people with diagnosed insomnia who took at least 600 mg daily for at least eight weeks [4]. The 2024 review of five trials also found improvements in sleep onset latency, total sleep time, and sleep efficiency [9].

The nuances

Extracts and dosages. Commercial supplements vary considerably. Most positive trials tested branded, standardized root extracts, such as KSM-66 at 600 mg daily or Shoden at 240 mg daily [6] [5]. Raw root powders and non-standardized formulations contain unpredictable concentrations of active withanolides, so trial results cannot be assumed to apply to unstandardized products [11].

Cortisol versus perceived stress. Lowering a biological marker does not always translate into feeling calmer. The 2025 meta-analysis found that while cortisol fell significantly across seven trials, scores on the Perceived Stress Scale did not show a statistically significant reduction across the six trials that tested it [3]. Cortisol levels fluctuate naturally throughout the day, and long-term consequences of suppressing cortisol remain unstudied [11].

Trial quality and industry ties. The certainty of evidence in the 2022 meta-analysis was rated as low due to high inconsistency across trials and risk of bias [1]. Many published trials are small, single-centre studies conducted in India, and several were funded directly by extract manufacturers [5] [1]. Independent, large-scale multicentre trials in broader populations are still lacking [5] [10].

What this means for you

Standardized ashwagandha root extract may offer modest short-term relief from feeling stressed or anxious, but it is not a substitute for medical evaluation or established treatments for anxiety disorders [1] [11].

Side effects. In clinical trials, side effects were generally mild, with mild stomach discomfort, nausea, loose stools, and drowsiness reported most frequently [2] [6].

Liver toxicity. Despite good tolerability in short trials, regulatory registries have identified serious safety concerns. A case series from Iceland and the United States documented five cases of drug-induced liver injury, presenting with jaundice and itching between 2 and 12 weeks after starting ashwagandha supplements [7]. A larger series from India reported eight cases of single-ingredient ashwagandha liver injury; five patients had chronic liver disease, and three died from acute-on-chronic liver failure [8]. Anyone with a history of liver disease should avoid ashwagandha [8].

Thyroid and medications. Ashwagandha can stimulate thyroid hormone synthesis, significantly raising free thyroid hormone levels in clinical trials [12]. People with thyroid conditions or those taking thyroid hormone medications should exercise caution, as cases of thyrotoxicosis have been documented [12]. Ashwagandha may also enhance the sedative effect of sleep medications or alcohol, and caution is warranted with immunosuppressants or diabetes drugs [11].

Pregnancy. Ashwagandha should be avoided during pregnancy and breastfeeding due to potential abortifacient effects and lack of safety data [11].

For full details on mechanisms, clinical claims, and drug interactions, see the Ashwagandha topic page.

Go deeper

  • Ashwagandha — Ashwagandha root extracts lower anxiety and stress scores and cortisol levels in meta-analyses of randomized trials, and small trials suggest better sleep.

References

  1. Does Ashwagandha supplementation have a beneficial effect on the management of anxiety and stress? A systematic review and meta-analysis of randomized controlled trials.. Phytother Res, 2022.
  2. Effects of Ashwagandha (Withania Somnifera) on stress and anxiety: A systematic review and meta-analysis.. Explore (NY), 2024.
  3. Dual impact of Ashwagandha: Significant cortisol reduction but no effects on perceived stress - A systematic review and meta-analysis.. Nutr Health, 2025.
  4. Effect of Ashwagandha (Withania somnifera) extract on sleep: A systematic review and meta-analysis.. PLoS One, 2021.
  5. An investigation into the stress-relieving and pharmacological actions of an ashwagandha (Withania somnifera) extract: A randomized, double-blind, placebo-controlled study.. Medicine (Baltimore), 2019.
  6. 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 J Psychol Med, 2012.
  7. Ashwagandha-induced liver injury: A case series from Iceland and the US Drug-Induced Liver Injury Network.. Liver Int, 2020.
  8. Ashwagandha-induced liver injury-A case series from India and literature review.. Hepatol Commun, 2023.
  9. Safety and efficacy of Withania somnifera for anxiety and insomnia: Systematic review and meta-analysis.. Hum Psychopharmacol, 2024.
  10. Effects of ashwagandha (Withania somnifera) on mental health in adults: A systematic review and dose-response meta-analysis of randomized controlled trials.. Complement Ther Med, 2026.
  11. Effects of Withania somnifera on Cortisol Levels in Stressed Human Subjects: A Systematic Review.. Nutrients, 2023.
  12. Efficacy and Safety of Ashwagandha Root Extract in Subclinical Hypothyroid Patients: A Double-Blind, Randomized Placebo-Controlled Trial.. J Altern Complement Med, 2018.