Educational note: This article is for general Ayurvedic education. Ashwagandha is a dietary supplement in the US, not an approved treatment for stress, anxiety, insomnia or any other condition. The cautions below come from the US National Center for Complementary and Integrative Health (NCCIH) and published case reports. Talk to a clinician before using it if any of them apply to you.

Ashwagandha (Withania somnifera) is the root of a small shrub in the nightshade family. It is a classical Ayurvedic herb and is now one of the most popular stress and sleep supplements in the US. Because it is so widely taken, this page starts with who should not take it.

Who Should Not Take Ashwagandha?

Avoid ashwagandha if you are pregnant or breastfeeding, have a thyroid or autoimmune condition, have liver disease or hormone-sensitive prostate cancer, or have surgery coming up. If you take any of the medicines in the table below, check with your prescriber first. NCCIH lists each of these cautions in its fact sheet (Source 1).

Pregnancy and breastfeeding. NCCIH says to avoid it during pregnancy and not to use it while breastfeeding.
Thyroid disorders. Ashwagandha may affect thyroid hormone levels. In a small 2018 trial of 50 people with subclinical hypothyroidism, 600 mg a day of root extract for 8 weeks raised T3 and T4 and lowered TSH compared with placebo (Source 8). It is not known whether the same happens in people with normal thyroid function. A published case report links ashwagandha to thyrotoxicosis, meaning too much thyroid hormone (Source 9). If you take levothyroxine or have an overactive thyroid, it could move your levels in a direction your clinician has not planned for.
Autoimmune conditions. NCCIH advises against it for people with autoimmune disorders. This includes Hashimoto's thyroiditis, which is both a thyroid and an autoimmune condition.
Liver disease. See the liver section below. The deaths reported so far were in people who already had chronic liver disease.
Hormone-sensitive prostate cancer. Ashwagandha may raise testosterone, so NCCIH says people with this cancer should avoid it.
Upcoming surgery. NCCIH does not recommend it for people about to have surgery. Stop it in advance and tell your surgical team you have been taking it. Ask them how far ahead to stop.

Drug interactions

NCCIH lists evidence that ashwagandha may interact with these medicine groups (Source 1):

Medicine group	Examples	Possible concern
Sedatives, including benzodiazepines	lorazepam, alprazolam, zolpidem, sleep aids	Added drowsiness
Thyroid hormone	levothyroxine	Thyroid levels may rise further
Immunosuppressants	medicines for transplants and some autoimmune conditions	Listed by NCCIH as a possible interaction
Anti-seizure medicines	anticonvulsants	Listed by NCCIH as a possible interaction
Diabetes medicines	metformin, insulin	Blood sugar may drop further
Blood pressure medicines	antihypertensives	Blood pressure may drop further

Liver injury: rare, but documented

Liver injury from ashwagandha is uncommon, but it is no longer only a theoretical risk. A 2020 case series described five people, three in Iceland and two in the US Drug-Induced Liver Injury Network. They developed jaundice, itching and nausea 2 to 12 weeks after starting it (Source 6). None developed liver failure, and liver tests returned to normal within one to five months in the four patients who were followed up. A 2023 series from India described eight cases with single-ingredient products. Five of those eight already had chronic liver disease. Three of the five developed acute-on-chronic liver failure and died (Source 7). The NIH LiverTox database also has an entry for ashwagandha (Source 10).

Stop taking it and get medical care promptly if you notice yellowing of the skin or eyes, dark urine, persistent itching, or unusual fatigue.

Ashwagandha side effects in women and men

Reported side effects include drowsiness, stomach upset, diarrhea and vomiting (Source 1). There are no separate side effect lists by sex. The cautions that matter most for women are those above: pregnancy and breastfeeding, thyroid conditions, and autoimmune conditions. In men, one trial found a rise in testosterone that was not significant against placebo (Source 3). The prostate cancer caution above applies.

What Is Ashwagandha Used For in Ayurveda?

In classical Ayurveda, ashwagandha is a rasayana, a herb taken over time to build resilience, and balya, meaning strength-giving. It is warming and grounding, which is why it is mainly matched to Vata. Its traditional uses include:

Strength and stamina, especially after illness or a long period of strain
Calming an unsettled Vata: restlessness, worry, light and broken sleep
Nourishing the deeper tissues, including reproductive tissue (shukra dhatu), as a tonic for both men and women
Building ojas, the Ayurvedic idea of reserve vitality

The classic preparation is ksheerapaka, the root powder simmered in milk and taken warm in the evening. The fat and warmth are meant to carry the herb and settle Vata. These are traditional uses, not modern treatment claims.

What Does the Research Say About Ashwagandha?

The best human evidence is for stress and sleep, and it is modest. Most trials are small and short. Many were run in India with branded root extracts, and some were funded by, or used product supplied by, extract manufacturers. Treat the results as promising, not settled.

Stress and cortisol. In a 60-day trial of 64 stressed adults, 300 mg of root extract twice daily lowered stress scores and serum cortisol compared with placebo (Source 2). In a 60-day trial of 60 adults, 240 mg a day of a different extract lowered one anxiety score and morning cortisol (Source 3). A second stress score did not reach significance in that trial.
Anxiety and stress overall. A 2022 meta-analysis of randomized trials found lower anxiety and stress scores with ashwagandha (Source 4). The authors also noted that individual trials had conflicting results.
Sleep. A 10-week trial in 60 people with insomnia found faster sleep onset and better sleep efficiency than placebo, using 300 mg twice daily (Source 5). A 2021 meta-analysis of five trials and 400 people found a small but significant effect on sleep. The effect was larger in people with insomnia, at 600 mg a day or more, over at least eight weeks (Source 11). The same review noted that long-term safety data are limited.

One proposed explanation is that ashwagandha dampens the hypothalamic-pituitary-adrenal (HPA) axis, the body's main stress-hormone system. The authors of one trial suggested this because morning cortisol fell (Source 3), but a drop in cortisol does not show how the stress scores changed. NCCIH notes that evidence is not enough to judge ashwagandha for most other uses, from athletic performance to cognition (Source 1).

What Forms of Ashwagandha Are There?

Ashwagandha is sold as plain root powder, which is the traditional form, and as standardized root extracts in capsules. Branded extracts such as KSM-66 and Sensoril differ in plant part, concentration and dose. The trials above used extracts at 240 to 600 mg a day for 8 to 10 weeks, and that dose range does not transfer directly to raw powder.

For a side-by-side of the forms and which suits sleep or daytime stress, see which ashwagandha is best. For product picks and what to check on a label, see our ashwagandha supplement guide. NCCIH considers it possibly safe in the short term, up to about three months, and says long-term safety is unknown (Source 1).

Frequently Asked Questions

Who should not take ashwagandha? People who are pregnant or breastfeeding, have a thyroid or autoimmune condition, liver disease, or hormone-sensitive prostate cancer, or have surgery coming up. Anyone taking sedatives, thyroid hormone, immunosuppressants, anti-seizure, diabetes or blood pressure medicines should check with a clinician first.

Can ashwagandha affect your thyroid? It may. A small 2018 trial in people with subclinical hypothyroidism found it raised T3 and T4 levels, and a case report links it to thyrotoxicosis. Avoid it with a thyroid condition unless your clinician agrees and monitors your levels.

Is ashwagandha bad for your liver? Liver injury is rare, but published case series from Iceland, the US and India document it, usually 2 to 12 weeks after starting. The reported deaths were in people who already had chronic liver disease.

How long does ashwagandha take to work? The trials measured effects after 8 to 10 weeks of daily use. It is not a herb for same-day effects, and NCCIH notes that safety beyond about three months is not well studied.

Can I take ashwagandha with sleep medication? Not without asking your prescriber. Ashwagandha may add to the drowsiness caused by sedatives, including benzodiazepines and other sleep aids.

Sources and Evidence

National Center for Complementary and Integrative Health (2023). "Ashwagandha." NCCIH fact sheet, last updated March 2023. nccih.nih.gov/health/ashwagandha
Chandrasekhar K, Kapoor J, Anishetty S (2012). "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 Journal of Psychological Medicine 34(3): 255-262. doi:10.4103/0253-7176.106022
Lopresti AL, Smith SJ, Malvi H, Kodgule R (2019). "An investigation into the stress-relieving and pharmacological actions of an ashwagandha (Withania somnifera) extract: A randomized, double-blind, placebo-controlled study." Medicine (Baltimore) 98(37): e17186. doi:10.1097/MD.0000000000017186
Akhgarjand C, Asoudeh F, Bagheri A, et al. (2022). "Does Ashwagandha supplementation have a beneficial effect on the management of anxiety and stress? A systematic review and meta-analysis of randomized controlled trials." Phytotherapy Research 36(11): 4115-4124. doi:10.1002/ptr.7598
Langade D, Kanchi S, Salve J, Debnath K, Ambegaokar D (2019). "Efficacy and Safety of Ashwagandha (Withania somnifera) Root Extract in Insomnia and Anxiety: A Double-blind, Randomized, Placebo-controlled Study." Cureus 11(9): e5797. doi:10.7759/cureus.5797
Björnsson HK, Björnsson ES, Avula B, et al. (2020). "Ashwagandha-induced liver injury: A case series from Iceland and the US Drug-Induced Liver Injury Network." Liver International 40(4): 825-829. doi:10.1111/liv.14393
Philips CA, Valsan A, Theruvath AH, et al. (2023). "Ashwagandha-induced liver injury - A case series from India and literature review." Hepatology Communications 7(10): e0270. doi:10.1097/HC9.0000000000000270
Sharma AK, Basu I, Singh S (2018). "Efficacy and Safety of Ashwagandha Root Extract in Subclinical Hypothyroid Patients: A Double-Blind, Randomized Placebo-Controlled Trial." Journal of Alternative and Complementary Medicine 24(3): 243-248. doi:10.1089/acm.2017.0183
van der Hooft CS, Hoekstra A, Winter A, de Smet PA, Stricker BH (2005). "Thyrotoxicosis following the use of ashwagandha" (in Dutch). Nederlands Tijdschrift voor Geneeskunde 149(47): 2637-2638. PMID: 16355578
LiverTox: Clinical and Research Information on Drug-Induced Liver Injury. "Ashwagandha." National Institute of Diabetes and Digestive and Kidney Diseases. ncbi.nlm.nih.gov/books/NBK548536
Cheah KL, Norhayati MN, Husniati Yaacob L, Abdul Rahman R (2021). "Effect of Ashwagandha (Withania somnifera) extract on sleep: A systematic review and meta-analysis." PLoS One 16(9): e0257843. doi:10.1371/journal.pone.0257843