We sell a supplement containing KSM-66, so we have an interest here. This is meant as a guide to reading a label, and we have been clear about what we are not allowed to claim. General information, not medical advice.
Quick answer: KSM-66 is a branded, standardised, full-spectrum extract of ashwagandha root, made by one manufacturer. It is the same plant as any other ashwagandha: the name tells you which extract is in the pack, not how much, so check the milligrams per daily serving. The Flissie Perimenopause Supplement (we make it) contains KSM-66 ashwagandha at 600mg per three capsules, with vitamin B6 and nine other botanicals. It costs £29 for 90 capsules, and on subscription the first month is free, then it renews automatically at £29 a month until you cancel.
What KSM-66 actually is
KSM-66 is a branded ashwagandha extract. Not a different plant, not a different species, just a specific, standardised, full-spectrum extract of ashwagandha root produced by one manufacturer.
Two words in that sentence matter.
Standardised means every batch is tested to contain a consistent level of the compounds used as markers, in this case withanolides. Unstandardised ashwagandha varies from harvest to harvest, so you cannot know what you are taking.
Full-spectrum means the extract aims to keep the natural balance of compounds found in the root rather than isolating one and concentrating it.
The practical point: KSM-66 is the extract used in a large share of the published clinical research on ashwagandha. That is the reason it appears on labels and the reason it costs more than generic root powder.
Why the dose is the thing to check
This is the part most brands would rather you did not look at.
The dose most commonly used in the clinical research on KSM-66 is 600mg a day. A lot of supplements containing KSM-66 use considerably less than that, and many do not tell you how much at all.
You will see labels that say things like a proprietary blend, or list ten botanicals with one combined weight. If the amount of each ingredient is not published, assume it is small. There is no other reason to hide it.
What to look for on the label:
- The named extract, KSM-66 or another branded one such as Sensoril, rather than just ashwagandha
- A stated milligram amount per daily serving, not per capsule if the serving is three capsules
- Root extract rather than root and leaf. Most of the research is on root
- An extract ratio or withanolide percentage if it is a generic extract
Look for a label that publishes the dose of every ingredient, not just the one on the front. We think that should be normal rather than notable.
KSM-66 against the alternatives
| Form | What it is | What to watch |
|---|---|---|
| KSM-66 | Branded, standardised, full-spectrum root extract | Check the milligrams. The name alone tells you nothing about dose |
| Sensoril | Another branded extract, root and leaf, higher withanolide content | Different research base. Typically used at a lower dose |
| Generic root extract | Standardised but unbranded | Look for a withanolide percentage or extract ratio |
| Root powder | Ground root, not extracted | Much weaker by weight. Not comparable to an extract at the same milligrams |
| Gummies | Usually a low dose plus sugar | Check the dose per gummy and the sugar content |
| Tea and coffee blends | Small amounts, taken for the ritual | Enjoyable, but not a meaningful dose |
The single most common mistake is comparing milligrams across forms. 600mg of a standardised extract and 600mg of ground root powder are not the same thing, and a cheap product will often be the second while looking like the first on the front of the pack.
What can be claimed for ashwagandha
Ashwagandha is a botanical with a long history of use in Ayurvedic practice, and a research base that is growing but not settled.
In the UK, botanical health claims sit on the EFSA Article 13.1 on-hold list, which means they have been submitted but not yet authorised. That is why we make no claim for any botanical.
Does ashwagandha reduce cortisol?
No authorised health claim says it does.
There is no authorised health claim in the UK for reducing, lowering or blocking cortisol. Any brand telling you their product does that is making a claim it cannot support, and a lot of the listings you will find are written for the US market where the rules are different.
There is published research looking at ashwagandha and cortisol, which is why the question is asked so often. But research existing is not the same as a claim being authorised, and we would rather explain the difference than exploit it.
What can honestly be said is that ashwagandha has a long history of traditional use, and no authorised health claim in the UK. If that sounds less exciting than what you have been told elsewhere, that is rather the point.
Who should not take it
This matters more than anything else on this page.
If you take thyroid medication, speak to your GP first. Ashwagandha has been shown in clinical studies to influence thyroid hormone levels, which means it may alter how your medication works.
If you are pregnant, breastfeeding or trying to conceive, do not take it.
If you take medication affecting mood or sedation, including SSRIs such as sertraline, speak to your GP. The evidence on interactions is limited, which is a reason for caution rather than confidence.
If you have or have had a hormone-sensitive condition, check with your specialist.
The UK Food Standards Agency opened a Call for Evidence on ashwagandha food supplements in 2024, which is worth knowing when you see a brand talk as though the picture is entirely settled.
The Food Standards Agency has since asked its Committee on Toxicity to assess the safety of ashwagandha in food supplements, and that review is ongoing.
What we make, and what we claim for it
The Flissie Perimenopause Supplement contains KSM-66 Ashwagandha at 600mg per daily serving, alongside Rhodiola, Chamomile, Chaste Tree, Maca, Wild Yam, Fennel, Broccoli Sprout Extract, Rosemary, Gymnema and Vitamin B6. Every dose is published on the product page.
Vitamin B6 has authorised health claims on the GB Nutrition and Health Claims Register, including contributions to normal psychological function and to the reduction of tiredness and fatigue. None of the ten botanicals has an authorised health claim, so we make none.
Beyond vitamin B6's authorised claims, we make no claim for it. Anything more would not be an authorised claim, and the ASA has been active in this category.
Not suitable in pregnancy or while breastfeeding, or with hormonal contraception, because it contains chaste tree. Avoid it if you have, have had or are at increased risk of a hormone-sensitive condition, because it contains wild yam. If you take thyroid medication, speak to your GP first. It costs £29 for 90 capsules; on subscription the first month is free, then it renews automatically at £29 a month until you cancel. See the formula and the full dose list.
Questions
What is KSM-66 ashwagandha?
A branded, standardised, full-spectrum extract of ashwagandha root, used in a large share of the published clinical research on the plant. It is not a different species, just a specific and consistent extract.
Is KSM-66 better than normal ashwagandha?
It is more consistent, because it is standardised, and it is the extract most of the research has used. Whether that is worth the extra cost depends on the dose. KSM-66 at a low dose is worse value than a well-dosed generic standardised extract.
What is the best KSM-66 dose?
600mg a day is the dose most commonly used in the clinical research. Check the amount per daily serving rather than per capsule, since many supplements have a serving of two or three.
Does ashwagandha reduce cortisol?
There is no authorised health claim in the UK for reducing or lowering cortisol, so no brand selling in the UK is permitted to tell you it does. Any brand that does is making a claim it cannot support.
Can you take ashwagandha with magnesium?
There is no known interaction and many people take both. If you take prescription medication, mention any combination to your GP or pharmacist.
Can you take ashwagandha with sertraline?
Speak to your GP before starting. Ashwagandha may have additive effects with medications affecting mood or sedation, and the evidence on interactions is limited. That applies to SSRIs including sertraline, and to sedatives.
Does ashwagandha make you sleepy?
It may add to the effects of medication affecting mood or sedation, so if you take any, speak to your GP before starting. No health claim about sleep or relaxation is authorised for ashwagandha in the UK, so we make none.
Is ashwagandha good for women?
It is used by all genders and most of the research is not sex-specific. The important caveats for women are that it is not suitable in pregnancy, while breastfeeding or when trying to conceive, and that anyone with a hormone-sensitive condition should check with their specialist.
How long does ashwagandha take to work?
No health claim for ashwagandha is authorised in the UK, so no one can honestly promise you a result, or a time by which you will notice one.
Is KSM-66 the same as Sensoril?
No. Both are branded standardised ashwagandha extracts, but Sensoril uses root and leaf with a higher withanolide content and is typically used at a lower dose. They have different research bases and are not interchangeable milligram for milligram.
Is KSM-66 ashwagandha safe?
The picture is not settled: the UK Committee on Toxicity is reviewing the safety of ashwagandha in food supplements. Do not take it if you are pregnant, breastfeeding or trying to conceive, speak to your GP first if you take thyroid medication or medication affecting mood or sedation, and check with your specialist if you have or have had a hormone-sensitive condition.
Is KSM-66 made from ashwagandha root or leaf?
Root. KSM-66 is a full-spectrum extract of ashwagandha root, while Sensoril, the other well-known branded extract, uses root and leaf. Most of the research on ashwagandha is on root.
Does the Flissie Perimenopause Supplement contain KSM-66?
Yes: the Flissie Perimenopause Supplement (we make it) contains KSM-66 ashwagandha at 600mg per daily serving of three capsules, with vitamin B6 and nine other botanicals, and no soya or red clover. It costs £29 for 90 capsules; on subscription the first month is free, then it renews automatically at £29 a month until you cancel. It is not suitable in pregnancy, while breastfeeding, or with hormonal contraception or a hormone-sensitive condition, and it needs your GP's go-ahead if you take thyroid medication.
