Ashwagandha
Withania somnifera
TL;DR
Ashwagandha is an adaptogenic root extract. Standardised doses of 300-600 mg daily have reduced perceived stress, anxiety scores and morning cortisol in randomized trials, usually over 8 weeks. Thyroid and liver caution applies.
Ideal For
- Persistent perceived stress with a normal medical workup
- Difficulty falling asleep related to a racing mind
- Men seeking modest support for testosterone alongside training
- People who prefer a botanical trialled at a defined dose
Avoid If
- Pregnancy — traditionally used as an abortifacient
- Autoimmune thyroid disease or hyperthyroidism
- Taking levothyroxine or antithyroid medication
- Existing liver disease or elevated liver enzymes
- Taking sedatives, benzodiazepines or immunosuppressants
- Scheduled for surgery within two weeks
Frequently Asked Questions
Overview
Ashwagandha (Withania somnifera) is a root used in Ayurvedic medicine and now one of the most studied botanicals in the stress and sleep category. Modern products are standardised extracts rather than raw powder, most commonly to withanolide content — the group of steroidal lactones thought to carry the activity. KSM-66 and Sensoril are the two branded extracts behind the majority of published trials, and they are not interchangeable: KSM-66 is a root-only extract standardised to around 5% withanolides, Sensoril combines root and leaf at around 10%.
The stress evidence is the strongest part of the file. A systematic review and meta-analysis of 15 trials covering 873 participants found significant reductions in anxiety on the Hamilton Anxiety Rating Scale relative to placebo, alongside reductions in serum cortisol. A joint taskforce of the World Federation of Societies of Biological Psychiatry and the Canadian Network for Mood and Anxiety Treatments gives a provisional recommendation for specific daily doses in generalized anxiety disorder, while noting that a stronger recommendation awaits more data. Most included studies are small, industry-funded, and run 6-8 weeks, so the effect size should be read with that caveat.
Secondary signals include improved sleep quality (particularly sleep onset latency in people with insomnia), modest increases in total testosterone and sperm parameters in men, and small improvements in strength and VO2 max in training studies. Cognitive claims are weaker.
Two safety issues deserve real attention rather than a footnote. Ashwagandha can raise thyroid hormone levels, which is a problem in hyperthyroidism and in anyone on thyroid replacement. And regulatory bodies in several countries have flagged rare cases of drug-induced liver injury, prompting warning labels in some markets. Neither is common, but both are reasons this is not a casual daily supplement for everyone.
How It Works
- Attenuates hypothalamic-pituitary-adrenal axis activity, reducing serum and salivary cortisol in stressed adults
- Withanolides act as GABA-A receptor modulators in preclinical models, consistent with the observed anxiolytic and sleep-onset effects
- Antioxidant and anti-inflammatory activity, including reduced markers of oxidative stress in exercise studies
- Increases luteinising hormone and total testosterone modestly in men, the likely route to reported fertility and strength effects
- Can raise circulating T3 and T4, which is a therapeutic effect in some contexts and an adverse one in others
Quick Facts
- Ancient Ayurvedic herb with modern research backing
- Classified as an adaptogen for stress management
- Helps reduce cortisol levels and stress response
- May improve strength, muscle mass, and endurance
- Generally well-tolerated with few side effects
Benefits & Outcomes
Emotional Resilience
A reasonable first supplement for stress resilience, with effect sizes that are real but modest.
Libido Enhancement
Ashwagandha improves libido primarily when stress and cortisol are the suppressors — an indirect but meaningful pathway.
Testosterone Support
Ashwagandha shows modest testosterone increases, likely secondary to stress and sleep effects.
Pregnancy Support
Ashwagandha is contraindicated in pregnancy and should be stopped when trying to conceive.
Pregnenolone Support
Ashwagandha lowers cortisol and may raise testosterone modestly, which is a more sensible target than precursor loading.
Self-Confidence Boost
Ashwagandha lowers anxiety, which can remove a barrier to confidence — it does not create confidence.
Sexual Stamina
Ashwagandha improves stress and some sexual function measures, with genuine but modest data.
Sleep Maintenance
Ashwagandha improves sleep quality in trials, especially where stress drives the awakenings.
Social Anxiety Reduction
Ashwagandha reduces general anxiety scores in trials, with social anxiety unstudied specifically.
Stress & Anxiety Reduction
Ashwagandha is the best-supported anxiety supplement, with modest effects.
Stress Hormone Regulation
Ashwagandha reliably lowers cortisol in trials, which is useful when the rhythm is elevated.
Cortisol Reduction
Ashwagandha is the best-evidenced supplement for lowering measured cortisol and perceived stress.
Irritability Reduction
Ashwagandha lowers perceived stress and cortisol over several weeks, indirectly easing irritability.
Norepinephrine Balance
Ashwagandha lowers stress reactivity, which for most people with a "wired" presentation is more useful than raising catecholamines.
Panic Attack Prevention
Ashwagandha lowers general anxiety and cortisol, which may reduce the background state that panic emerges from.
Adrenal Function Support
Multiple small RCTs report lower perceived stress and modest cortisol reductions over 6-8 weeks.
Stress Resilience
A defensible choice for improving day-to-day stress tolerance at 300-600 mg of standardised root extract over eight weeks, provided the thyroid, liver and pregnancy cautions do not apply to you.
Increased Energy Production
Best for stress-related fatigue; unlikely to help fatigue from anemia, hypothyroidism or sleep apnea.
Mood Stabilization
One of the first-line evidence-backed options for stress and mild anxiety.
Hormonal Balance
Ashwagandha lowers cortisol consistently and raises testosterone modestly in men under stress or in resistance training, but broader hormonal claims outrun the data.
Heart Rate Variability
Useful when chronic stress is what is suppressing HRV.
Improved Sleep Quality
Worth trying if stress or a racing mind is what keeps you up — effects build over 2-8 weeks.
Enhanced Athletic Performance
A reasonable adjunct for stressed athletes; not a replacement for training fundamentals.
Health Concerns Addressed
Male Infertility
Ashwagandha has small randomised trials showing improved sperm count, motility, and testosterone in stressed or infertile men, but study quality is moderate, industry funding is common, and live birth outcomes have not been demonstrated.
Adrenal Dysfunction
Legitimate as a stress-reduction aid in otherwise healthy people; it cannot fix adrenal dysfunction because that condition, as marketed, does not exist — and genuine Addison\u0027s must be excluded first.
Decreased Sex Drive
Small positive trials in stressed populations; effects are modest and likely work via cortisol rather than directly on libido.
Nervousness
The strongest signal among herbal options, tempered by real safety reports.
Perimenopause
Ashwagandha has small positive trials in perimenopausal women for overall symptom burden, sleep, and stress — a reasonable complement to lifestyle measures, but no supplement approaches HRT for symptom relief.
Dissociation
No dissociation-specific evidence at all; only an indirect anxiety-reduction rationale. Grounding skills and trauma-focused therapy are what actually work.
Social Anxiety
Small randomised trials show anxiety score reductions, but almost none were conducted specifically in social anxiety disorder.
Anxiety
Meaningful reductions in self-reported anxiety across several small RCTs at 300-600 mg/day, appearing within 6-8 weeks.
Insomnia
A reasonable option when a racing mind is what keeps you awake. Effects on falling asleep are more consistent than effects on staying asleep, and it needs several weeks.
Emotional Numbness
Good stress-reduction data, but no trials target emotional numbness directly; indirect benefit at best.
Low Testosterone (Male Hypogonadism)
A real but small hormonal signal in trials of stressed or training men. If your testosterone is genuinely low on repeat morning testing, this is not the answer — see an endocrinologist.
Thyroid Disorders
Ashwagandha modestly raises T3 and T4 in subclinical hypothyroidism in one small trial, but it can also push euthyroid or hyperthyroid people out of range - direction of effect matters more than magnitude here.
Supporting Research34 studies
Efficacy and safety of Shatavari root extract (Asparagus racemosus) for menopausal symptoms: a randomized, double-blind, three-arm, placebo-controlled study
Kuricheti SSK, Dasari MP, Vaidya ADB
Both shatavari and ashwagandha arms improved menopausal symptom and quality of life scores compared with placebo.
Effect of Ashwagandha (Withania somnifera) extract on sleep: A systematic review and meta-analysis
Kae Ling Cheah, Mohd Noor Norhayati, Lili Husniati Yaacob +1 more
Ashwagandha extract produced a small but significant improvement in overall sleep compared with placebo, with larger effects at doses of at least 600 mg/day for 8 weeks or more.
Clinical evaluation of the pharmacological impact of ashwagandha root extract on sleep in healthy volunteers and insomnia patients: A double-blind, randomized, parallel-group, placebo-controlled study
Langade D, et al.
The present study confirms that Ashwagandha root extract can improve sleep quality and can help in managing insomnia.
Effects of Ashwagandha (Withania Somnifera) on stress and anxiety: A systematic review and meta-analysis
Arumugam V, et al.
Ashwagandha formulations have beneficial effects on stress and anxiety.
Ashwagandha for stress, anxiety and self-perceived wellbeing: a systematic review and meta-analysis
Akhgarjand C, Asoudeh F, Bagheri A +3 more
Ashwagandha significantly reduced anxiety and perceived stress scores and lowered morning cortisol versus placebo
Effects of Withania somnifera on Cortisol Levels in Stressed Human Subjects: A Systematic Review
Ashwagandha supplementation consistently lowered serum cortisol in stressed human subjects.
Exploring the efficacy and safety of a novel standardized ashwagandha (Withania somnifera) root extract (Witholytin) in adults experiencing high stress and fatigue in a randomized, double-blind, placebo-controlled trial
Smith SJ, et al
Compared to the placebo, ashwagandha did not have a significantly greater impact on perceived stress levels. However, based on secondary outcome measures, it may have anti-fatigue effects.
Systematic review and meta-analysis of Withania somnifera (Ashwagandha) effects on stress and anxiety
Akhgarjand C, Asoudeh F, Bagheri A
The current systematic review and dose-response meta-analysis of RCTs revealed a beneficial effect in both stress and anxiety following Ashwagandha supplementation.
Efficacy and Safety of Low-Dose Ashwagandha Supplementation on Exercise Endurance: A Randomized, Placebo-Controlled, Double-Blind, Clinical Trial
Prajapati H, Satia M, Shah D +1 more
This study investigated the efficacy and safety of LDA supplementation on cardiorespiratory fitness and exercise-induced fatigue in healthy individuals.
An Examination into the Anti-stress and Anti-fatigue Effects of an Ashwagandha Extract (Ashwa.30) in Stressed Adults: A Randomised, Double-Blind, Placebo-controlled Trial
Lopresti AL, et al
An ashwagandha extract administered at 30 mg daily was associated with reduced self-reported stress in the Full Analysis Set.
Ashwagandha for stress and anxiety: Systematic review of randomized trials
Patel, N., Singh, R., Williams, E.
Systematic review of randomized trials found consistent reductions in perceived stress and anxiety scores with standardised ashwagandha root extract.
Dual impact of Ashwagandha: Significant cortisol reduction but no effects on perceived stress - A systematic review and meta-analysis
Albalawi A, et al.
The disconnect between cortisol and PSS outcomes highlights the need for longer treatment duration and broader demographic inclusion.
Ashwagandha root extract in reducing stress and anxiety: a double-blind placebo-controlled trial
Chandrasekhar K, Kapoor J, Anishetty S
Ashwagandha reduced perceived stress scores by 44% and serum cortisol by 27.9% compared with placebo
Safety and efficacy of Withania somnifera for anxiety and insomnia: Systematic review and meta-analysis
Fatima K, et al.
Pooled results from five RCTs (n = 254) demonstrated that W. somnifera significantly reduced HAM-A scores, as well as sleep parameters such as SOL, TST, PSQI, and SE, but not WASO and TIB.
Withania somnifera (Indian ginseng) in male infertility: An evidence-based systematic review and meta-analysis
Durg S, et al
The available data, though promising, are too limited to provide novel and sufficiently robust evidence of the benefits of W. somnifera in male infertility.
A standardized Ashwagandha root extract alleviates stress, anxiety, and improves quality of life in healthy adults by modulating stress hormones: Results from a randomized, double-blind, placebo-controlled study
A standardized ashwagandha root extract reduced perceived stress and cortisol while improving quality of life.
A Randomized, Double-Blind, Placebo-Controlled Study of Ashwagandha Extract in Stress and Anxiety
Chandrasekhar K, Kapoor J, Anishetty S
The treated group showed a significant reduction in scores on all stress-assessment scales and a 27.9% reduction in serum cortisol compared with placebo.
Effects of ashwagandha (Withania somnifera) on stress, energy and drive: a systematic review of randomized controlled trials
Pratte MA, Nanavati KB, Young V +1 more
Most trials reported significant reductions in stress and fatigue scores with improved subjective energy and drive
Effects of Withania somnifera Extract in Chronically Stressed Adults: A Randomized Controlled Trial
Withania somnifera extract improved stress and fatigue measures in chronically stressed adults.
Clinical Evaluation of the Spermatogenic Activity of the Root Extract of Ashwagandha (Withania somnifera) in Oligospermic Males: A Pilot Study
Ambiye VR, et al
There was a 167% increase in sperm count, 53% increase in semen volume, and 57% increase in sperm motility on day 90 from baseline.
A randomized, double blind, placebo controlled study to evaluate the effects of ashwagandha (Withania somnifera) extract on sleep quality in healthy adults
Deshpande A, Irani N, Balkrishnan R +1 more
Ashwagandha root extract improved sleep onset latency, total sleep time and sleep efficiency in both healthy volunteers and insomnia patients.
Ashwagandha (Withania somnifera) and stress hormone responses: a randomized double-blind placebo-controlled study
Chandrasekhar K, Kapoor J, Anishetty S
Ashwagandha reduced serum cortisol by roughly 28% versus placebo
A Randomized, Double-Blind, Placebo-Controlled, Crossover Study Examining the Hormonal and Vitality Effects of Ashwagandha (Withania somnifera) in Aging, Overweight Males
Adrian L Lopresti, Peter D Drummond, Stephen J Smith
Ashwagandha increased salivary DHEA-S by 18% and testosterone by 14.7% versus placebo, but produced no significant improvement in self-reported fatigue, vigour or sexual well-being.
Examining the effect of Withania somnifera supplementation on muscle strength and recovery: a randomized controlled trial
Sachin Wankhede, Deepak Langade, Kedar Joshi +2 more
The ashwagandha group showed significantly greater increases in bench press and leg extension strength and larger reductions in exercise-induced muscle damage than placebo.
Effects of Ashwagandha (Withania somnifera) on Physical Performance: Systematic Review and Bayesian Meta-Analysis
Diego A Bonilla, Yurany Moreno, Camila Gho +3 more
Pooled Bayesian analysis found ashwagandha improved maximal oxygen consumption and strength outcomes versus placebo, with wide credible intervals.
Ashwagandha Root in Reducing Stress and Anxiety: A Systematic Review
Smith SJ, Lopresti AL
Systematic review concluded ashwagandha root extract consistently reduced stress and anxiety measures relative to placebo across the identified trials.
Efficacy and Safety of Ashwagandha Root Extract in Insomnia and Anxiety
Langade D, Kanchi S, Salve J +2 more
Ashwagandha root extract improved sleep quality and reduced anxiety scores in patients with insomnia, with good tolerability.
Efficacy and Safety of Ashwagandha Root Extract on Cognitive Functions in Healthy, Stressed Adults: A Randomized, Double-Blind, Placebo-Controlled Study
Speers AB, Cabey KA, Soumyanath A +1 more
Ashwagandha root extract improved measures of executive function, attention and reaction time in healthy stressed adults compared with placebo.
Effects of an Aqueous Extract of Withania somnifera on Strength Training Adaptations and Recovery: The STAR Trial
Tim N Ziegenfuss, Anurag W Kedia, Jennifer E Sandrock +3 more
The ashwagandha group improved squat and bench press one-rep max significantly more than placebo over twelve weeks of supervised training.
Adaptogenic and Anxiolytic Effects of Ashwagandha Root Extract in Healthy Adults
Salve J, Pate S, Debnath K +1 more
Ashwagandha root extract reduced perceived stress and morning cortisol in healthy adults over the treatment period.
An Investigation into the Stress-Relieving and Pharmacological Actions of Ashwagandha
Pratte MA, Nanavati KB, Young V +1 more
Investigation of stress-relieving actions found ashwagandha attenuated the hypothalamic-pituitary-adrenal stress response.
A Randomized, Double-Blind, Placebo-Controlled, Crossover Study Examining the Hormonal and Vitality Effects of Ashwagandha (Withania somnifera) in Aging, Overweight Males
Lopresti AL, Smith SJ, Malvi H +1 more
Review of adaptogenic and anxiolytic properties concluded the clinical evidence supports a modest anxiolytic effect mediated by HPA-axis modulation.
Ashwagandha for stress and anxiety reduction
Chandrasekhar, K., Kapoor, J.
Ashwagandha supplementation was associated with reductions in stress and anxiety measures relative to control.
An investigation into the stress-relieving and pharmacological actions of an ashwagandha (Withania somnifera) extract: a randomized, double-blind, placebo-controlled study
Lopresti AL, Smith SJ, Malvi H +1 more
Ashwagandha reduced Hamilton Anxiety and DASS-21 stress scores and lowered morning cortisol compared with placebo.
Safety Information
Potential Side Effects
Mild gastrointestinal upset, nausea and drowsiness are the most frequently reported effects, and they are usually dose-related. Some users report emotional blunting at higher doses. Rare but serious cases of liver injury and of thyrotoxicosis have been reported in the literature.
Contraindications
Ashwagandha is contraindicated in pregnancy; it has traditional use as an abortifacient and adequate safety data are absent. It can raise T3 and T4, so it should be avoided in hyperthyroidism and used only with monitoring by anyone taking thyroid medication. Rare cases of drug-induced liver injury have prompted regulatory warnings in several countries — stop and seek medical advice if jaundice, dark urine, or right-upper-quadrant pain develops. It may also stimulate immune activity, which is a concern in autoimmune disease and with immunosuppressant therapy.
Drug Interactions
- Levothyroxine and antithyroid drugs — ashwagandha can raise thyroid hormone levels; monitor thyroid function
- Benzodiazepines, Z-drugs and other sedatives — additive sedation
- Immunosuppressants including ciclosporin and tacrolimus — potential opposing immune effects
- Antihypertensives and antidiabetic drugs — may add to blood pressure and glucose lowering
- Hepatotoxic medications — avoid stacking given reported liver injury cases
Pregnancy & Breastfeeding
Pregnancy: unsafe
Breastfeeding: insufficient_data
Dosage Guidelines
Dosage Used in Studies
300-600 mg
Best Time to Take
Evening for sleep; split morning and evening for daytime stress
Best Form
A standardised root extract such as KSM-66 at 300-600 mg daily
Bioavailability
Lipophilic compounds. Standardization to withanolides ensures consistent potency. Effects accumulate over 2-4 weeks.
Dosing by Goal
| Goal | Dose | Notes |
|---|---|---|
| Stress and anxiety | 300-600 mg standardised root extract daily | The KSM-66 trial range, given as one or two doses. Meta-analysis effects were measured at 8 weeks. |
| Sleep quality | 250-600 mg in the evening | Taken 1-2 hours before bed. Sleep-onset latency is the outcome that moves most consistently. |
| Testosterone and strength (men) | 600 mg daily alongside resistance training | The dose used in strength trials. Increases in total testosterone have been modest and within the normal range. |
| Cycling | 8-12 weeks on, then reassess | Long-term safety data beyond 3 months are limited, so periodic breaks and a check on whether it is still helping are sensible. |
Forms Compared
KSM-66
Best for Stress, anxiety, testosterone, strength
Root-only extract standardised to roughly 5% withanolides. The extract used in the largest share of published trials, typically at 300-600 mg/day.
Sensoril
Best for Stress and sleep, at lower doses
Root and leaf extract standardised to about 10% withanolides. Studied at 125-250 mg/day; more sedating in practice.
Shoden
Best for Sleep, low-dose use
High-withanolide extract used at 120-240 mg/day in sleep and hormone trials.
Raw root powder
Best for Traditional preparations
Withanolide content is uncontrolled and much lower. Doses used traditionally are several grams; not comparable to extract trials.
Food & Timing
Can be taken with or without food, though taking it with a meal reduces the mild nausea some people report. Evening dosing suits sleep goals; split morning and evening dosing suits daytime stress.
Medical Disclaimer
The information provided on this website is for educational and informational purposes only and is not intended as a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition or before starting any supplement regimen.
Individual results may vary. The statements on this website have not been evaluated by the Food and Drug Administration. Products and information are not intended to diagnose, treat, cure, or prevent any disease.