Ashwagandha
In short
Summary of findings for quick reference
In Ayurveda, ashwagandha belongs to the rasayana tradition of restorative preparations. The root is the main part used. It is also known as Asgandh in South Asian Unani medicine. Classical formulas and modern pharmacopoeias document its use. Historical significance does not establish the strength of modern clinical evidence.
Small clinical trials suggest changes in stress, sleep and cortisol. Chandrasekhar and colleagues (2012) and Lopresti and colleagues (2019) each studied use for 60 days. Salve and colleagues (2019) reported better self-rated sleep quality in stressed adults. Bonilla and colleagues (2021) reviewed physical-performance trials in women and men. Results are not uniform, and differences between preparations make comparison difficult.
Ashwagandha should not be taken during pregnancy or breastfeeding. Particular caution is warranted because of possible thyroid effects, medicine interactions and reports of liver injury. Avoid it if you have an existing liver disorder. Studies use different root extracts and, in some cases, root-and-leaf extracts. Their doses are not interchangeable. There is no EMA HMPCEuropean Medicines Agency, Committee on Herbal Medicinal Products (HMPC) monograph for the root.
Clinical evidence ↔ Historical significanceWe display two separate evidence categories: clinical evidence from modern trials and historical significance from documented healing tradition. Both are valuable, but they answer different questions.Read more
In every encyclopedia entry we evaluate two distinct categories of evidence. Clinical evidence as used in trials meets a narrower but scientifically essential bar. At the same time, the hundreds of thousands of plant species worldwide have only partially been captured and tested in modern studies.
Alongside the trial picture our researchers compile a comprehensive overview of where and since when a plant has been used across different traditions of natural medicine. When a plant has been used as a medicinal plant in many cultures across many generations, that historical significance deserves to be visible too.
Our position: a truly informative overview emerges only when both categories sit side by side. We communicate transparently what counts as what.
Overview
Ashwagandha (Withania somnifera) is a small evergreen shrub of the Solanaceae (nightshade) family, native to a broad region extending from southern Europe through Africa into Asia. The dried root has been used in Ayurvedic tradition for centuries and is classified there as a rasayana, a category of restorative herbs. The Sanskrit name translates roughly to the smell of a horse, a reference to the distinctive aroma of the fresh root.
Ashwagandha is sometimes called Indian ginseng, but it is not a ginseng species and is not botanically related to the Asian or American ginsengs. There is no EU herbal monograph for the root. The European Medicines Agency Committee on Herbal Medicinal Products (EMA HMPCEuropean Medicines Agency, Committee on Herbal Medicinal Products (HMPC)) concluded in a 2013 final public statement that one could not be established. Ashwagandha is sold as a food supplement in some European countries, but its regulatory status is not uniform across the EU. Its traditional use rests on the Ayurvedic record. Modern research interest has grown around a small body of randomised trials on stress, sleep, and cortisol.
History
Ashwagandha is among the best-known herbs of the Ayurvedic materia medica. Its root is regarded as a rasayana, a restorative tonic. Traditional preparations include the dried root ground into a fine powder. The Sanskrit name means “smell of a horse”, referring to the characteristic aroma of the fresh root.
Ashwagandha is known in the European supplement market mainly through modern preparations. There is no EU herbal monograph for the root. In 2013, the EMA Committee on Herbal Medicinal Products concluded that one could not be established (EMA/HMPC/681519/2012). The plant’s traditional significance and its current regulatory status need to be distinguished.
Mechanism
The main bioactive group in ashwagandha is a family of steroidal lactones known as withanolides. Named withanolides reported in the root include withanolide A, withaferin A, and the glycosides withanoside IV and withanoside V. Standardisation of branded extracts is expressed as a percentage of total withanolides, and the values differ considerably between products. The root extract KSM-66 used in several trials is standardised to five per cent withanolides, while other branded extracts declare ten per cent or more, in some cases for a different compound group, the withanolide glycosides.
Mechanistic accounts in the research literature describe ashwagandha as an adaptogen acting on the hypothalamic-pituitary-adrenal (HPA) axis, with proposed effects on cortisol regulation and on neurotransmitter signalling. These mechanisms are drawn from a mix of in-vitro work, animal studies, and small human trials, and the picture is not settled. The link between specific withanolides and any clinical effect in people is plausible but not firmly established. Ashwagandha is best read as a traditional rasayana with a small but growing modern research base.
Modern clinical research on ashwagandha is small in scale and recent in vintage. Chandrasekhar and colleagues published a 2012 randomised controlled trial in adults with chronic stress, reporting reductions in perceived stress and serum cortisol over sixty days with a standardised root extract. Lopresti and colleagues reported lower cortisol and improvement on a clinician-rated anxiety scale in 2019, but the difference in self-reported symptoms versus placebo was not statistically significant. Salve and colleagues studied healthy adults with elevated stress for eight weeks in 2019. Self-reported sleep quality improved; this was not a trial specifically in people with insomnia.
Bonilla and colleagues reviewed physical-performance studies in healthy women and men in 2021. They found positive signals but emphasized differences between studies and the need for more comparable research. Stress findings are not uniformly positive either: Smith and colleagues found no advantage over placebo for perceived stress in adults with stress and fatigue in 2023. Extracts and short trials vary considerably. Ashwagandha has no authorized EU health claim.
Evidence
| Outcome | Class | Grade | Effect | Studies | Refs |
|---|---|---|---|---|---|
| Chronic stress and perceived stressChandrasekhar and colleagues (2012) reported lower perceived stress and serum cortisol after 60 days with 300 milligrams KSM-66 twice daily. Lopresti and colleagues (2019) found lower cortisol and improvement on a clinician-rated anxiety scale, but the difference in self-reported symptoms versus placebo was not statistically significant. Both trials were small and short.Adults with chronic stress or elevated stress levels | EmergingEmerging research. Early small trials suggest an effect but await replication. | CEvidence quality grade C. Mixed or limited evidence. Small trials, signals, or traditional use under an EMA HMPC traditional-use monograph. This is an evidence rating, not a product endorsement. | Modest Improvement | [1][2][5] | |
| Self-reported sleep quality under elevated stressSalve and colleagues (2019) studied healthy adults with elevated stress taking 250 or 600 milligrams of root extract daily for eight weeks. Self-reported sleep quality improved compared with placebo. This trial did not study an exclusively insomnia population or measure sleep onset latency as a separate outcome.Healthy adults with elevated stress | EmergingEmerging research. Early small trials suggest an effect but await replication. | CEvidence quality grade C. Mixed or limited evidence. Small trials, signals, or traditional use under an EMA HMPC traditional-use monograph. This is an evidence rating, not a product endorsement. | Modest Improvement | [3] | |
| Cortisol levelsLopresti and colleagues (2019) and Chandrasekhar and colleagues (2012) reported lower serum cortisol after 60 days in each trial. Both studies were small and short. A change in this laboratory marker alone does not establish a health benefit.Adults under chronic or elevated stress | EmergingEmerging research. Early small trials suggest an effect but await replication. | CEvidence quality grade C. Mixed or limited evidence. Small trials, signals, or traditional use under an EMA HMPC traditional-use monograph. This is an evidence rating, not a product endorsement. | Modest Improvement | [1][2] | |
| Physical performanceBonilla and colleagues (2021) reviewed physical performance in healthy women and men, including strength, endurance and recovery. Results were generally positive, but comparability between studies was limited. This was not a testosterone-focused review restricted to resistance-trained men.Healthy women and men | EmergingEmerging research. Early small trials suggest an effect but await replication. | DEvidence quality grade D. Preliminary signal. A single small trial, pilot result, or laboratory or animal model. Clinical relevance unclear. This is an evidence rating, not a product endorsement. | Mixed Effect | [4] |
Usage
Forms and preparation
Modern preparations often contain standardized extracts in capsule form. KSM-66 is made from root, while Sensoril contains root and leaf. Findings for root-and-leaf extracts do not automatically apply to root-only preparations. Root powder remains a traditional preparation, for example mixed into warm milk. Withanolide content alone does not make different preparations equivalent. Use depends on the specific preparation. Ashwagandha can cause drowsiness, particularly relevant when also taking sedating medicines. Tinctures and decoctions are also available. When changing products, compare the plant part, extract amount and standardization. Do not convert doses based only on withanolide content.
Dosage
Some studies use 300 to 600 milligrams of a particular root extract daily. Chandrasekhar and colleagues (2012) tested 300 milligrams twice daily; Salve and colleagues (2019) compared 250 and 600 milligrams daily in stressed adults. Lopresti and colleagues (2019) used 240 milligrams of a differently standardized extract. These doses are not directly transferable because composition differs. Traditional plain root powder is used in gram quantities. Different preparations do not establish a universal starting dose. Follow the specific product instructions and seek medical advice if you have a medical condition or take medication. Many studies last several weeks to about three months. This is not a recommendation for an equally long course of self-treatment; longer-term safety is insufficiently studied.
Safety
Look-alikes
FAQs
What is ashwagandha?
Ashwagandha (Withania somnifera) is an Ayurvedic root in the Solanaceae (nightshade) family, traditionally used as a rasayana, a restorative and regenerative herb. In modern use it is most often taken as a standardised root extract in capsule form. In some European countries the herb is sold as a food supplement; there is no EU herbal monograph for it, because the EMA HMPC concluded in 2013 that one could not be established. Its traditional use to support people under mental and physical stress and to support sleep rests on the Ayurvedic record. Despite the nickname Indian ginseng, it is not botanically related to Asian or American ginseng.
Can I take ashwagandha during pregnancy?
No. Ashwagandha is not recommended during pregnancy or breastfeeding because safety is insufficiently established. The frequently repeated claim of an abortifacient effect is disputed and should not be presented as established fact. Seek medical advice before use if trying to conceive.
How long does it take for ashwagandha to work?
Many studies assess changes over several weeks. This does not predict whether or when you will notice an effect. A fixed onset of action has not been established. Seek medical advice for persistent sleep or stress-related complaints rather than simply extending use.
What is the usual dose?
Some studies test 300 to 600 milligrams of a particular root extract daily; other extracts use substantially different doses. KSM-66 contains root and Sensoril root and leaf. Traditional root powder is used in gram quantities. A suitable dose cannot be calculated from withanolide content alone. The specific preparation and medical or pharmaceutical advice matter.
5 sources.
- Chandrasekhar K, Kapoor J, Anishetty S. 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. 2012. doi:10.4103/0253-7176.106022
- Lopresti AL, Smith SJ, Malvi H, Kodgule R. An investigation into the stress-relieving and pharmacological actions of an ashwagandha (Withania somnifera) extract: A randomized, double-blind, placebo-controlled study. 2019. PMID:31517876
- Salve J, et al.. Adaptogenic and Anxiolytic Effects of Ashwagandha Root Extract in Healthy Adults: A Double-blind, Randomized, Placebo-controlled Clinical Study. 2019. PMID:32021735
- Bonilla DA, Moreno Y, Gho C, Petro JL, Odriozola-Martínez A, Kreider RB. Effects of Ashwagandha (Withania somnifera) on Physical Performance: Systematic Review and Bayesian Meta-Analysis. 2021. doi:10.3390/jfmk6010020
- Smith SJ, Lopresti AL, Fairchild TJ. 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. 2023. doi:10.1177/02698811231200023
Legal notice: The depiction of historical significance and traditional use is context within our encyclopedia and not a health claim for any product, not a treatment promise, and not a substitute for medical advice. What may be stated on product labels, product pages, or in advertising is governed by the applicable legal requirements.