Ashwagandha Benefits, Side Effects and Who Should Not Take It

"The word natural tells you nothing about dose or safety. Two ashwagandha products can differ in plant part, extract strength and contamination. The research applies to the extract that was tested, not to every churna or gummy on the shelf. Ask what is in the bottle before you ask what it can do." - Dt. Trishala Goswami, MSc Clinical Nutritionist, Diabetes Educator

Dt. Trishala Goswami, MSc Clinical Nutritionist · Diabetes Educator · Certified Nutrigenomics Specialist · Last Updated: October 2026

The short answer: the best-supported ashwagandha benefits are modest, short-term improvements in stress, anxiety and sleep, plus small strength and testosterone gains in men, mostly from small 6 to 8 week trials of specific extracts. It is not a cure for anything. It can change thyroid hormone levels and, rarely, injure the liver, so pregnant women, people with thyroid, liver or autoimmune disease, and anyone on regular medicines should ask a doctor first.

Ashwagandha (Withania somnifera), also called Indian ginseng or winter cherry, has been used in the traditional Ayurvedic and Unani systems of India as an adaptogen, a loose term for something said to help the body resist stress (NIH Office of Dietary Supplements). In India you will find it as churna (root powder), tablets, capsules, gummies, and increasingly as an add-on in protein powders.

Traditional use does not tell us what a capsule from an online store will do for you. Here is what the clinical trials show, where they fall short, and the safety signals regulators have acted on.

What is actually in an ashwagandha supplement?

The root and the leaf of the plant have different chemical make-ups. Most commercial supplements use root extract, while some combine root and leaf (ODS). The compounds most often studied are called withanolides.

Withanolide content varies with the plant part, the extraction method and the extraction ratio (TGA, July 2026). KSM-66 is a root extract; Sensoril and Shoden combine root and leaf. A result from one does not automatically apply to another, or to loose churna.

Ashwagandha for stress and anxiety: what the trials show

• A 2021 systematic review identified seven trials with 491 adults, all in India, lasting 6 to 8 weeks. Trials used 240 to 1,250 mg a day of extract, or 12,000 mg a day of root granules. Ashwagandha reduced stress and anxiety scores and serum cortisol compared with placebo, and in several trials the benefits appeared larger in groups given 500 to 600 mg a day than in groups given lower doses (summarised by ODS).
• A 2022 meta-analysis pooled 12 randomised trials with 1,002 participants. Anxiety and stress fell compared with placebo, but the authors rated the certainty of evidence as low (Akhgarjand et al., Phytotherapy Research, 2022).
• A 2025 meta-analysis in people with diagnosed mental disorders, mostly anxiety disorders, included 14 studies with 713 people. The median dose trials used was 600 mg a day and median follow-up was 8 weeks. Symptoms improved, with large differences between studies (BJPsych Open, 2025).

Not every analysis agrees. A 2025 meta-analysis of 488 participants found a significant fall in cortisol but no significant effect on perceived stress scores (Nutrition and Health, 2025).

The fair reading: several small, short trials, mostly from India and using branded extracts, point the same way. None shows ashwagandha replaces therapy or prescribed medicine. For the food and lifestyle side, see our guide to cortisol and the stress belly.

Ashwagandha for sleep

The evidence here is smaller. A 2021 meta-analysis of five randomised trials with 400 participants found a small but significant effect on overall sleep. The effect was clearer in trials of adults with diagnosed insomnia, in trials that used 600 mg a day or more, and in trials lasting at least 8 weeks (Cheah et al., PLoS One, 2021).

In one trial, 80 adults took a KSM-66 root extract (two 300 mg capsules a day) or placebo for 8 weeks, and those with insomnia fell asleep faster. In another, 150 adults with poor sleep took a root and leaf extract (Shoden, two 60 mg capsules a day) for 6 weeks; sleep quality improved by 72% with ashwagandha and 29% on placebo (both summarised by ODS).

Ashwagandha for testosterone, strength and the gym

• Strength: 57 young men new to weight training took 300 mg of root extract twice a day or placebo for 8 weeks. Bench press strength rose by 46.0 kg with ashwagandha compared with 26.4 kg on placebo (Wankhede et al., JISSN, 2015).
• Testosterone: In a crossover trial of overweight men aged 40 to 70, a root and leaf extract (Shoden, 21 mg withanolide glycosides a day) for 8 weeks gave a 14.7% greater rise in testosterone than placebo. There was no difference in fatigue, vigour or sexual well-being (Lopresti et al., American Journal of Men's Health, 2019).
• Pooled results: A 2026 meta-analysis of 20 trials with 1,249 participants found small increases in testosterone and moderate gains in muscle strength, clearest in physically active people, and no effect on body weight or body fat (Frontiers in Pharmacology, 2026).

Because ashwagandha may raise testosterone, the NIH advises that men with hormone-sensitive prostate cancer should avoid it (NCCIH). For training, our athletic nutrition programme covers the food side.

Ashwagandha for women: PCOS, thyroid and hormones

PCOS. When we searched in October 2026, we could not find a randomised controlled trial of ashwagandha in women with PCOS. Our evidence-based guide to PCOS supplements reaches the same view: it may help stress, but it is not a frontline PCOS supplement. PCOS involves hormones such as insulin and testosterone not working properly, and excess facial or body hair is a main symptom (NHS). ANSES advises people with endocrine disorders, particularly thyroid disorders and hyperandrogenism (high male-type hormones), not to take ashwagandha supplements (ANSES, 2024). Talk to your gynaecologist before you start.

Thyroid. In a trial of 50 people with subclinical hypothyroidism, 600 mg a day of root extract for 8 weeks lowered TSH and raised T3 and T4 compared with placebo (Sharma et al., 2018). But three case reports describe thyrotoxicosis (an overactive thyroid state) in women aged 32 to 73 taking ashwagandha, which resolved after stopping (ODS). The NIH lists thyroid hormone medicines among possible interactions and does not recommend ashwagandha for people with thyroid disorders (NCCIH). If you take thyroxine or anti-thyroid medicine, or have an overactive thyroid, speak to your endocrinologist first. For the food side, see foods that help and hurt the thyroid.

Ashwagandha side effects: the safety evidence

Common side effects

In trials, ashwagandha is generally well tolerated for up to about 3 months. Mild stomach upset, loose stools, nausea and drowsiness are the most common side effects. Its safety over many months or years is not known (ODS). A 2026 trial of 1,002 adults taking 600 mg a day of root extract for 8 weeks found no serious adverse events and no change in liver or kidney tests compared with placebo (Phytotherapy Research, 2026). It was funded by an Indian pharmaceutical company, and 8 weeks cannot rule out rare reactions.

Liver injury

This is the most important safety signal, though rare. The NIH LiverTox database rates ashwagandha as a likely cause of clinically apparent liver injury (LiverTox, updated December 2024). According to LiverTox:

• Injury typically appeared 2 to 12 weeks after starting, often with jaundice and itching.
• Most cases were mild to moderate and settled within 1 to 4 months of stopping.
• Rare cases were fatal or needed an emergency liver transplant, particularly in people with pre-existing liver disease or cirrhosis.
• Products can be mislabelled or mixed, but in several cases the product was tested and contained only ashwagandha.

An Indian case series described 8 patients from three hospitals. Five had pre-existing chronic liver disease, and 3 died of acute-on-chronic liver failure (Philips et al., Hepatology Communications, 2023). Australia's TGA has received 11 reports of possible liver injury in total and calls the risk very rare (TGA, July 2026). India's Ministry of Ayush, in its 2024 safety dossier, found no evidence of intrinsic liver toxicity from the root and concluded root extract is safe (as summarised by TGA).

LiverTox advises avoiding ashwagandha in people with cirrhosis or advanced chronic liver disease, and the TGA advises avoiding it in anyone with an existing liver disorder. If you have been told you have a fatty liver, raise it with your doctor before taking any herbal product. Stop the supplement and see a doctor promptly if you notice yellow eyes or skin, itching, nausea, unusual tiredness or abdominal discomfort, the symptoms reported in published cases (ODS).

Pregnancy and breastfeeding

The NIH says ashwagandha should be avoided during pregnancy and not used while breastfeeding (NCCIH). ANSES advises against it in pregnancy, and as a precaution in breastfeeding and under 18 (ANSES, 2024). Australia requires a pregnancy warning on the label of certain preparations (TGA). The American Herbal Pharmacopoeia disputes claims that the root causes abortion (ODS), but safety data in pregnancy are lacking. If you are pregnant, breastfeeding or trying to conceive, leave it out unless your obstetrician advises otherwise.

Autoimmune disease

The NIH does not recommend ashwagandha for people with autoimmune disorders (NCCIH), and Denmark's food agency notes it can affect the immune system (Fødevarestyrelsen).

Medicine interactions

The NIH also does not recommend ashwagandha for people about to have surgery (NCCIH), and ANSES advises against it for people with heart conditions (ANSES, 2024). We found no specific data for kidney disease, so if you have chronic kidney disease, ask your nephrologist before any herbal supplement.

Which countries restrict ashwagandha?

In short, Denmark is the only country in this table to ban sales outright. ANSES notes that supplement rules are not harmonised across the EU: Denmark and Germany recommend not using it in supplements, while France permits sales (ANSES, 2024).

How to judge an ashwagandha product

ANSES concluded that the extracts and plant parts used in studies are too poorly characterised to link any one compound to the effects reported (ANSES, 2024). A 2008 JAMA study of 193 Ayurvedic medicines of many kinds, bought online in 2005, found detectable lead, mercury or arsenic in 20.7%, at similar rates in US-made and Indian-made products. It was not a study of ashwagandha, but it is why batch testing matters (Saper et al., JAMA, 2008).

If you and your doctor decide to try it, check:

1. Plant part on the label. Root only, or root and leaf. Indian regulators moved in 2026 to stop the use of leaves in food products.
2. Standardisation. A stated withanolide percentage, ideally matching an extract that has been tested in trials.
3. Single ingredient. "Testosterone booster" blends combine many herbs, and LiverTox records a suspected liver injury case linked to one such eight-ingredient product (LiverTox).
4. A traceable manufacturer. A licence number and batch number on the pack, not an unbranded churna sold loose.
5. Third-party testing for heavy metals and contaminants, where the brand publishes it.

For readers abroad: ashwagandha is widely sold in the UK, US, Canada and Australia. Australia's TGA warns that products bought online from overseas are not regulated by it for quality or safety (TGA), and the same caution applies elsewhere. If you live in Denmark, it cannot legally be sold there as a food.

Why talk to a doctor before you start

Ashwagandha is sold like a food but behaves more like a mild medicine: it changes hormone levels, can cause drowsiness, and rarely injures the liver. Speak to your doctor first if:

• You take any regular medicine, especially for thyroid, diabetes, blood pressure, sleep, anxiety, seizures or the immune system.
• You have a thyroid, liver, heart or autoimmune condition, or PCOS with high androgens.
• You are pregnant, breastfeeding, trying to conceive, or under 18.
• You have surgery coming up, or you have hormone-sensitive prostate cancer.

Your doctor may want to check your thyroid or liver tests. And if stress or poor sleep is the real issue, ask what is driving it before adding a supplement.

This is general nutrition guidance. For personalised medical care, consult your doctor or book a 1:1 consultation with Dt. Trishala Goswami.

Related reading

• Cortisol and weight gain: the stress belly connection
• Best supplements for PCOS: an evidence-based guide
• Is protein powder safe? What Indian buyers should check
• Turmeric and curcumin: how much do you really need?
• Thyroid diet: foods that help vs foods that hurt

Wondering whether a supplement fits your health picture? Book a consultation with Dt. Trishala Goswami to review your reports, medicines and goals before you add anything new, working alongside your doctor. Online consultations for clients in India and abroad. You can also explore our PCOS program.