Does ashwagandha really work?

For perceived stress and cortisol there are trials that find an effect versus placebo, with doses of 300-600 mg of standardised extract for 8-12 weeks. The systematic review that summarises them warns that they are small, heterogeneous studies, so the evidence is promising but still limited, not comparable to creatine’s.

How much ashwagandha should you take a day?

The most cited trials use 300 mg of standardised root extract twice a day. What matters is not the milligrams on the tub but the extract: 600 mg of 10:1 extract is not the same as 600 mg of powdered root, and many products play on that confusion.

What is the difference between KSM-66 and powdered root?

Branded extracts are standardised to a specific withanolide content and are the ones used in published trials. Ground root is the whole plant, unconcentrated. Comparing their milligrams directly makes no sense, and here paying for the extract means paying for the product that was studied.

How long does it take to work?

Trials measure at 8-12 weeks and improvements appear gradually. It is not an acute-effect product: if you expect to notice something on the first night, you are judging it by the wrong criterion.

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Ashwagandha · Moderate evidence

What ashwagandha is for and what the evidence says

The short answer. Ashwagandha is the fashionable plant and, unlike others, it has trials behind it: those measuring perceived stress and cortisol find an effect versus placebo, with small samples and durations of 8 to 12 weeks. It is not an anxiolytic and replaces nothing. And one detail changes what you buy: almost all studies use specific, standardised extracts, not powdered root.

There are studies in favour, but few, with small samples or measuring markers instead of outcomes. No figure on this page is attributed to a specific product: the effect belongs to the ingredient and every number carries its source next to it.

01 What it does and how much

Each row is a measured effect, with the figure the study gives and the source number. Where the evidence gives no figure, the column says so instead of making up a percentage.

Effects of ashwagandha with their source
Effect	How much	Detail
Perceived stress	improves versus placebo	Measured with self-reported stress scales in trials of 8 to 12 weeks. It is subjective data, which is what is usually measured in this field. [1][2]
Blood cortisol	drops in the trials	The trial with a high-concentration root extract found a notable decrease versus placebo. It is a marker, not a symptom: lower cortisol does not automatically mean living better. [2]
Trial dose	300 mg of extract, twice a day	It is the most repeated regime, with standardised root extract. A tub of powdered root at that figure is not the same. [2]
Quality of the evidence	small samples	The systematic review says it clearly: promising results with small, heterogeneous studies. That is why it appears here as moderate evidence and not strong. [1]

02 How to take it

Dose. 300 to 600 mg a day of standardised extract, split or in one serving.
When. With food. Many take it at night for its effect on rest.
How long before you notice it. 4 to 12 weeks in the trials. It is not something you notice on day one.

Details that change the result

Look for the extract ratio (10:1, 12:1) or the name of the standardised extract. "Ashwagandha 1000 mg" of powdered root is not equivalent to 300 mg of concentrated extract.
Branded extracts are the ones used in the trials; they cost more and they are the only ones anything can be said about with a study in hand.
Do not combine with sedatives or thyroid medication without asking: it interacts.
Not during pregnancy or breastfeeding. And with autoimmune or thyroid disease, a medical decision.

03 When it makes sense and when it does not

Worth it if

Periods of sustained high stress, as support and not as a solution.
Poor rest linked to that stress, where several trials look at sleep.
When you can allow 8-12 weeks to judge whether it does anything for you.

Not worth it if

As a substitute for treatment of diagnosed anxiety or depression.
Expecting an acute effect on day one, like caffeine.
During pregnancy, breastfeeding or with thyroid medication without discussing it with your doctor.

04 Sources

Every figure above comes from here. They are position stands from scientific societies, meta-analyses and peer-reviewed reviews: if a claim cannot hang from one of these lines, it is not on the page. References are cited in their original form.

Pratte MA et al. An alternative treatment for anxiety: a systematic review of human trial results reported for the Ayurvedic herb ashwagandha (Withania somnifera). J Altern Complement Med. 2014;20(12):901-908. doi:10.1089/acm.2014.0177
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. 300 mg de extracto dos veces al dia durante 60 dias. doi:10.4103/0253-7176.106022

This is not medical advice. It is what some studies say about an ingredient, not a protocol for you. With an illness, medication or pregnancy involved, the decision belongs to a healthcare professional who knows you.

Questions about ashwagandha

Answered with the data on this page

Does ashwagandha really work?: For perceived stress and cortisol there are trials that find an effect versus placebo, with doses of 300-600 mg of standardised extract for 8-12 weeks. The systematic review that summarises them warns that they are small, heterogeneous studies, so the evidence is promising but still limited, not comparable to creatine’s.
How much ashwagandha should you take a day?: The most cited trials use 300 mg of standardised root extract twice a day. What matters is not the milligrams on the tub but the extract: 600 mg of 10:1 extract is not the same as 600 mg of powdered root, and many products play on that confusion.
What is the difference between KSM-66 and powdered root?: Branded extracts are standardised to a specific withanolide content and are the ones used in published trials. Ground root is the whole plant, unconcentrated. Comparing their milligrams directly makes no sense, and here paying for the extract means paying for the product that was studied.
How long does it take to work?: Trials measure at 8-12 weeks and improvements appear gradually. It is not an acute-effect product: if you expect to notice something on the first night, you are judging it by the wrong criterion.

And now, which to buy

Prices, kept apart from the evidence

This page explains what ashwagandha does and deliberately names no brand. The comparison is the other half: 119 products from 8 stores from €0.027 per capsule, sorted by price and by how verifiable their certification is.

See the ashwagandha comparison

Other guides

What each supplement does, with its sources