Ashwagandha: What It Is, Properties, and Scientific Research

Ashwagandha (Withania somnifera) is an evergreen shrub of the Solanaceae family, whose root is traditionally used in Ayurveda. Today, ashwagandha powder and standardized extracts are included in dietary supplements positioned for support during stress, anxiety, and sleep disorders. Some small clinical studies do show a possible effect, but ashwagandha is not a universal sedative and does not replace treatment prescribed by a doctor [1, 2].

Important: the composition of different supplements varies significantly. Root extract, a root-and-leaf mixture, plant powder, and liquid forms are not equivalent in terms of active substance concentration. Therefore, the results of a study of a specific standardized extract cannot be automatically applied to any product labeled “ashwagandha.”

What ashwagandha is

Ashwagandha grows in regions of Asia, Africa, and the Middle East. It is also called “Indian ginseng” and “winter cherry,” although the plant is not related to true ginseng. In traditional medical systems, the root was most often used. The main studied components are withanolides — a group of steroidal lactones, although the presumed effect of the plant may be associated not only with them [1].

The term “adaptogen” describes substances that are presumed to help the body adapt to physical and emotional stress. This is a broad concept, not an official indication for treating a specific disease.

Ashwagandha is available on the market in several forms:

powdered ground root — contains a natural complex of substances, but the concentration of withanolides may vary noticeably between batches;
capsules or tablets with powder or extract — it is important to look not only at the number of milligrams, but also at the plant part, extract type, and standardization;
liquid extracts and tinctures — their concentration depends on the production technology; there is less clinical data on such forms;
standardized extracts, including KSM-66 — these are specific extract production technologies with a defined withanolide content. KSM-66 is not a separate plant species and does not automatically make any product effective.

Who ashwagandha may be suitable for

Supplements with ashwagandha may be considered by adults as an additional, not primary, method of support for:

a feeling of prolonged stress and increased psycho-emotional load;
difficulty falling asleep or reduced subjective sleep quality;
fatigue associated with stress;
temporary decrease in concentration against the background of overload.

Before starting use, it is advisable to discuss the supplement with a doctor or pharmacist, especially if symptoms persist, worsen, or the person is already taking medicines. Anxiety disorder, depression, persistent insomnia, and cognitive impairment require diagnosis: ashwagandha should not delay seeking medical help.

Adaptogenic and anti-stress properties

The most studied area is the effect of ashwagandha on the subjective feeling of stress and cortisol levels. It is assumed that plant extracts may affect the hypothalamic-pituitary-adrenal system, which is involved in the body’s stress response. In clinical studies lasting mainly 6–8 weeks, participants taking ashwagandha more often reported reduced stress and fatigue, and in some studies their cortisol levels decreased compared with placebo [1, 3].

At the same time, the results cannot be considered final. The studies were small, conducted with different extracts and doses, and some were funded by ingredient manufacturers. Therefore, it is more accurate to speak of a possible moderate effect, not a proven ability to “normalize stress hormones” in all people.

Anxiolytic effect and mental health

In a number of studies, anxiety scale scores decreased and subjective well-being improved during ashwagandha use. However, data on the anxiolytic effect remain heterogeneous: the NIH notes possible benefit for stress, but considers the evidence of an effect on anxiety insufficiently certain [1, 2].

Ashwagandha does not act like a prescription anxiolytic and cannot be used instead of psychotherapy or prescribed medicines. In cases of panic attacks, severe anxiety, intrusive thoughts, sudden worsening of sleep, or reduced daily functioning, you should consult a doctor.

Effect of ashwagandha on sleep

Several small clinical studies show that standardized ashwagandha extracts may moderately improve sleep quality, reduce the time needed to fall asleep, and increase total sleep duration. In a 2021 systematic review and meta-analysis, the effect was small but statistically significant and more noticeable in people with insomnia, especially when using the extract at a dose of about 600 mg per day for at least eight weeks [1, 4].

However, the studies used different extracts, dosages, and sleep assessment methods, so the results cannot be automatically applied to all supplements with ashwagandha. In chronic insomnia, frequent nighttime awakenings, or pronounced daytime sleepiness, the supplement should not replace diagnosis and treatment prescribed by a doctor [2].

Neuroprotective effects and cognitive functions

Laboratory and preclinical studies associate withanolides with antioxidant activity, effects on inflammatory processes, and signaling between nerve cells. These results explain scientific interest in ashwagandha as a potential neuroprotector, but by themselves they do not prove brain protection in humans.

Small 2024 clinical trials showed improvement in certain indicators of memory, attention, energy, and mood in healthy adults after taking standardized extracts [5, 6]. At the same time, NCCIH states that there is still insufficient evidence of ashwagandha’s benefit for cognitive functions [2]. The supplement cannot be considered a means of preventing or treating dementia, Alzheimer’s disease, or other neurological diseases.

Mood regulation and possible antidepressant effect

In some studies, participants reported improved mood and overall psychological well-being. Possible mechanisms are associated with reduced stress response and effects on neurotransmitter systems, but a significant part of these data comes from experiments, not large clinical studies.

Today, ashwagandha is not considered a proven antidepressant. You must not independently replace prescribed medicines with it or combine them without consulting a doctor. In cases of depressed mood lasting more than two weeks, loss of interest in usual activities, pronounced weakness, or thoughts of self-harm, professional medical help is needed.

Dosage and how to take ashwagandha

There is no single universal dose: products differ by plant part, extraction method, and withanolide content. In stress studies, approximately 240–1250 mg of extract per day was used, and the most commonly studied range was 500–600 mg per day [1]. In a well-known study of standardized KSM-66 extract, 300 mg twice daily was used for 60 days [3]. These figures describe the conditions of specific studies and are not a personal prescription.

Practical rules for safe use:

follow the instructions for the specific product and do not recalculate the dose of one extract to another based only on milligrams;
do not combine several supplements with ashwagandha at the same time;
if you have a sensitive stomach, take the product during or after meals, unless the instructions require otherwise;
if drowsiness occurs, move intake to the evening and do not drive until you understand your individual reaction;
do not continue use for months without monitoring: most safety data relate to short-term use — up to three months [1, 2].

If the expected effect is absent, you should not increase the dose on your own. This may increase the risk of adverse reactions but does not guarantee additional benefit.

Contraindications and who needs special caution

Ashwagandha should not be taken without consultation with a doctor:

during pregnancy and breastfeeding;
by children and adolescents due to insufficient safety data;
in thyroid diseases or when taking thyroid hormones;
in autoimmune diseases and treatment with immunosuppressants;
in acute or chronic liver diseases, as well as after drug-induced liver injury;
before planned surgery;
in hormone-sensitive prostate cancer;
in case of known allergy to ashwagandha or components of a specific supplement.

People with diabetes mellitus, low blood pressure, epilepsy, and chronic diseases also need prior consultation, because ashwagandha may affect the action of medicines and certain physiological indicators [2, 7].

Possible side effects

With short-term use, ashwagandha is usually tolerated satisfactorily, but some people may experience:

drowsiness, weakness, or dizziness;
stomach discomfort, nausea, diarrhea, or vomiting;
headache;
skin rash or other signs of an allergic reaction.

Rare cases of liver injury associated with ashwagandha supplements have been described. If yellowing of the skin or eyes, dark urine, pale stool, severe itching, pain under the ribs on the right side, persistent nausea, or unusual weakness occurs, use should be stopped immediately and medical help should be sought [2, 7, 8].

Overdose

The exact toxic dose of ashwagandha has not been established, since the composition and concentration of supplements differ. If the recommended amount is exceeded, drowsiness, nausea, vomiting, diarrhea, abdominal pain, dizziness, and other adverse reactions may increase. Theoretically, the risk of effects on the thyroid gland, glucose levels, blood pressure, and liver is also higher.

In case of accidental intake of a large dose, stop using the product, keep the packaging, and contact a doctor or emergency service. Do not induce vomiting or take other products to “neutralize” the supplement on your own.

Interaction of ashwagandha with medicines

Ashwagandha may change the effect of medicines. Special caution is needed when taking it simultaneously with:

sedatives and sleeping pills — drowsiness may increase;
anticonvulsant medicines;
thyroid hormones — thyroid indicators may change;
immunosuppressants — the presumed immunomodulatory action may conflict with the purpose of treatment;
glucose-lowering medicines — additional lowering of glucose is possible;
antihypertensive medicines — additional lowering of blood pressure is possible.

This list is not exhaustive. If a person takes any prescription medicines, especially on a regular basis, the supplement should be agreed with a doctor or pharmacist [2, 7].

Frequently asked questions about ashwagandha

Is ashwagandha a medicine or a dietary supplement?

Most products with ashwagandha are sold as dietary supplements, not medicines. They do not undergo the same assessment procedure for effectiveness and safety as registered medicines.

How quickly does ashwagandha work?

In studies of stress and sleep, the effect was usually assessed after 6–8 weeks of regular use. An immediate effect should not be expected, and the absence of an effect is not a reason to increase the dose on your own.

Can ashwagandha be taken every day?

In clinical studies, it was taken daily, mainly for up to 8–12 weeks. The safety of long-term use for many months or years has not been established.

When is it better to take it — in the morning or evening?

There is no universal time. If drowsiness occurs, evening intake is more convenient; if the product does not cause a sedative effect, follow the instructions and individual tolerability. The daily dose of some extracts is divided into two intakes.

Which form of ashwagandha is better?

More clinical data has been accumulated for standardized extracts, but even they differ in composition. It is important to assess the plant part, percentage of withanolides, dose per serving, and manufacturer reliability, not only the technology name.

Can ashwagandha be combined with antidepressants?

Not on your own. Data on all combinations is insufficient, and the medicines may affect the central nervous system. The combination must be discussed with the doctor who knows the treatment regimen.

Does ashwagandha help with depression and anxiety disorder?

There is preliminary data on reducing some symptoms of stress and anxiety, but ashwagandha does not replace diagnosis, psychotherapy, and medical treatment. Evidence for depression is insufficient.

References

Office of Dietary Supplements, National Institutes of Health. Ashwagandha: Is it helpful for stress, anxiety, or sleep? Fact Sheet for Health Professionals. Updated May 2, 2025. https://ods.od.nih.gov/factsheets/Ashwagandha-HealthProfessional/
National Center for Complementary and Integrative Health. Ashwagandha: Usefulness and Safety. https://www.nccih.nih.gov/health/ashwagandha
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. Indian J Psychol Med. 2012;34(3):255–262. https://pubmed.ncbi.nlm.nih.gov/23439798/
Cheah K. L. et al. Effect of Ashwagandha (Withania somnifera) extract on sleep: A systematic review and meta-analysis. PLoS One. 2021;16(9):e0257843. https://pubmed.ncbi.nlm.nih.gov/34559859/
Leonard M. et al. Acute and repeated ashwagandha supplementation improves markers of cognitive function and mood. Nutrients. 2024. https://pubmed.ncbi.nlm.nih.gov/38931168/
Kale S. et al. Safety and efficacy of ashwagandha root extract on cognitive functions, energy, and mood in adults: A randomized, double-blind, placebo-controlled study. 2024. https://pubmed.ncbi.nlm.nih.gov/39498904/
German Federal Institute for Risk Assessment (BfR). Ashwagandha: food supplements with potential health risks. Communication 39/2024. https://www.bfr.bund.de/cm/349/ashwagandha-food-supplements-with-potential-health-risks.pdf
LiverTox: Clinical and Research Information on Drug-Induced Liver Injury. Ashwagandha. National Institute of Diabetes and Digestive and Kidney Diseases. https://www.ncbi.nlm.nih.gov/books/NBK548536/

Author: Natalia Kandybey, Candidate of Pharmaceutical Sciences, Quality Director of PJSC Pharmaceutical Factory “VIOLA”

Ashwagandha: What It Is, Properties, Dosage, and Contraindications