Ashwagandha: KSM-66 Vs Sensoril Vs Shoden, Benefits, Dosage And Safety

Ashwagandha (Withania somnifera) is an Ayurvedic herb whose standardized extracts, most famously KSM-66 ashwagandha, have been tested in a few dozen small randomized trials for stress and sleep. Pooled results show modest reductions in perceived stress and anxiety and a small improvement in sleep, usually at 240 to 600 mg of extract per day for eight weeks or longer.^[5][6] It is not risk-free: rare but serious liver injury, thyroid effects and pregnancy concerns are documented, and Denmark banned it in supplements in 2023.^[10][12]

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What Is Ashwagandha And How Does It Work?

Ashwagandha is a small shrub in the nightshade family. Its root, and in some products its leaf, has been used in Ayurvedic medicine for centuries and is marketed today as an adaptogen, meaning an herb proposed to help the body handle stress.

The compounds most often credited with its effects are withanolides, a family of steroidal lactones. Supplement makers standardize extracts to a stated withanolide percentage, but the percentages are not directly comparable between brands because extraction methods and plant parts differ.^[12]

The leading hypothesis is that ashwagandha dampens activity of the hypothalamic-pituitary-adrenal (HPA) axis, the hormonal stress system. That idea is supported mainly by trials showing lower morning cortisol, but researchers themselves describe this mechanism as tentative.^[2]

KSM-66 Vs Sensoril Vs Shoden: Ashwagandha Extracts Compared

Most “best ashwagandha” debates come down to which branded extract a product uses. The three with the most research behind them are not interchangeable, and their doses should never be swapped one-for-one.

Extract	Plant Part	Standardization (As Reported)	Typical Trial Dose
KSM-66	Root only	More than 5% withanolides	300 mg twice daily (600 mg/day); stress trials ranged 240–1,250 mg/day
Sensoril	Root and leaf	Standardized withanolide glycosides (percentage varies by product)	125–500 mg/day
Shoden	Root and leaf	About 35% withanolide glycosides (21 mg per 60 mg capsule)	120–240 mg/day

Sources: NIH Office of Dietary Supplements and the trials cited below.^[12][7]

KSM-66 Ashwagandha

KSM-66 is a full-spectrum root extract and the most widely studied branded form. The NIH Office of Dietary Supplements lists KSM-66 as the extract used in key sleep research at two 300 mg capsules per day, which is where the common “ashwagandha 300 mg twice daily” advice comes from.^[12] Its best-known trial gave 64 chronically stressed adults 300 mg of a high-concentration full-spectrum root extract twice daily for 60 days and found larger drops in stress questionnaire scores and serum cortisol than placebo.^[1] Like most ashwagandha studies, it was small, single-center and conducted in India.

Ashwagandha Sensoril

Sensoril combines root and leaf. Its foundational trial (130 enrolled, 98 completers) tested 125 mg once daily up to 250 mg twice daily for 60 days and reported lower anxiety scores, serum cortisol, C-reactive protein and blood pressure versus placebo.^[7] That study appeared in a small trade journal rather than a major peer-reviewed outlet, so weigh it accordingly.

Shoden Ashwagandha

Shoden is the most concentrated of the three. In a 60-day trial in 60 stressed but healthy adults, 240 mg once daily reduced Hamilton Anxiety scores and morning cortisol versus placebo; the reduction on a second stress scale (DASS-21) did not reach significance.^[2]

Ashwagandha Benefits: What The Research Shows

Stress And Perceived Stress (Evidence: Moderate)

Across 12 randomized trials with 1,002 participants, ashwagandha reduced stress scores versus placebo, with a large pooled effect size (SMD −1.75). The authors still rated certainty as low because trials were small and results varied widely between studies (I² = 83%).^[6] In one dose-comparison trial, both 250 mg and 600 mg per day lowered perceived stress over eight weeks, with stronger effects at the higher dose.^[3]

Cortisol (Evidence: Moderate)

Several trials report lower serum or morning cortisol, including the KSM-66, Shoden and Sensoril studies above.^[1][2][3] A lower cortisol number is a lab marker, not proof you will feel better, and cortisol varies a lot through the day.

Anxiety (Evidence: Limited To Moderate)

The same 2022 meta-analysis found lower anxiety scores (SMD −1.55), again with very high between-study variability.^[6] NCCIH describes the evidence for anxiety as unclear, so ashwagandha should not replace treatment for an anxiety disorder.^[11]

Sleep (Evidence: Moderate)

A 2021 meta-analysis of five RCTs (400 participants) found a small but significant improvement in overall sleep (SMD −0.59), with larger effects in people with insomnia, at doses of 600 mg/day or more and with treatment of at least eight weeks.^[5] In a 10-week trial measuring sleep with wrist actigraphy, 300 mg of root extract twice daily shortened the time it took to fall asleep and improved sleep efficiency compared with placebo.^[4] Note that ashwagandha is not a sedative in the way sleep medications are; benefits built up over weeks.

Ashwagandha For Adrenal Fatigue And “Adrenal Support”

“Adrenal fatigue” is a popular wellness label, not an established medical diagnosis. A systematic review of 58 studies found no evidence that it exists as a medical condition, and endocrinology societies do not recognize it.^[13] No ashwagandha trial we reviewed enrolled people on that basis. The trials above studied stressed adults and people with insomnia. If you have persistent exhaustion, ask a doctor to rule out real problems such as thyroid disease, anemia, sleep apnea or depression before trying “adrenal support” supplements.

Ashwagandha As A Nootropic (Evidence: Preliminary)

Ashwagandha is often sold as a nootropic, but its human evidence is mostly about stress and sleep rather than memory or focus. Any cognitive benefit you notice is more likely to come indirectly, from sleeping better or feeling less frazzled. For direct focus and memory options, see our guides to the best supplements for focus and the best supplements for memory.

Ashwagandha Dosage: Studied Doses

Purpose	Extract And Dose	Duration	Study
Chronic stress	Full-spectrum root extract (KSM-66 type), 300 mg twice daily	60 days	Chandrasekhar 2012[1]
Stress, cortisol	Shoden, 240 mg once daily	60 days	Lopresti 2019[2]
Stress, sleep quality	Aqueous root extract, 125 mg or 300 mg twice daily	8 weeks	Salve 2019[3]
Insomnia and anxiety	Root extract, 300 mg twice daily	10 weeks	Langade 2019[4]
Chronic stress	Sensoril, 125 mg once daily to 250 mg twice daily	60 days	Auddy 2008[7]

In plain terms: for KSM-66, the studied dose is 600 mg per day, usually split as 300 mg twice daily. For Shoden, 120 to 240 mg per day. A dose-response analysis suggested benefits for stress and anxiety in roughly the 300 to 600 mg/day range.^[6] Products labeled “ashwagandha 800 mg” or higher are not necessarily better; check whether the label lists an extract or plain root powder, because plain powder is far less concentrated.

Forms And What To Look For

• A named extract. KSM-66, Sensoril or Shoden lets you match a product to a studied dose. Generic “ashwagandha root powder” is a different product.
• A stated withanolide percentage. Useful for consistency, but compare it only within the same extract type.
• Third-party testing. Several liver injury cases involved products that were never analyzed, and LiverTox notes contamination or mislabeling cannot always be ruled out.^[10] Look for a certificate of analysis or independent testing.
• Single-ingredient products. Combination “adrenal” blends make it impossible to know your actual ashwagandha dose.

Ashwagandha Side Effects And Safety

In trials lasting up to about three months, ashwagandha has generally been well tolerated. The most common side effects are drowsiness, stomach upset, loose stools and nausea.^[11][12] Long-term safety is not known.

Liver Injury

This is the most serious documented risk. LiverTox, the NIH database on drug-induced liver injury, gives ashwagandha a likelihood score of “B” (a likely cause of clinically apparent liver injury). Reported cases typically appear 2 to 12 weeks after starting a product, often with jaundice and itching, and usually resolve within one to four months of stopping. Fatal liver failure and rare liver transplants have also been reported.^[10] A published case series from Iceland and the U.S. Drug-Induced Liver Injury Network documented several of these cases.^[9] Stop taking it and contact a doctor if you notice yellowing of the skin or eyes, dark urine, itching or unusual fatigue. People with existing liver disease should avoid it.^[10]

Thyroid Effects

Ashwagandha can raise thyroid hormone levels. In an 8-week trial in 50 adults with subclinical hypothyroidism, 600 mg/day of root extract lowered TSH and raised T3 and T4 compared with placebo.^[8] That sounds helpful, but it also means ashwagandha could push someone into excess thyroid hormone; the NIH has noted case reports of thyrotoxicosis that resolved after stopping.^[12]

Pregnancy And Breastfeeding

NCCIH advises avoiding ashwagandha during pregnancy and not using it while breastfeeding.^[11] Concern stems from older reports of possible miscarriage; the evidence is debated, but there is no reason to take the risk.^[12]

Hormones

Ashwagandha may increase testosterone. In the Shoden trial, testosterone rose in men compared with their baseline, though the difference versus placebo was not significant.^[2] NCCIH advises people with hormone-sensitive prostate cancer to avoid it.^[11]

Countries That Have Restricted Ashwagandha

Denmark banned ashwagandha in food supplements in 2023, following a 2020 risk assessment by the Technical University of Denmark that raised concerns about effects on pregnancy, the thyroid and sex hormones. In 2024, France’s food safety agency (ANSES) advised certain groups, including pregnant and breastfeeding women and people with endocrine disorders, not to use it.^[12] These decisions were precautionary; they reflect uncertainty about long-term safety rather than proof of widespread harm. Ashwagandha remains legal as a supplement in the United States.

Drug Interactions And Who Should Avoid It

NCCIH and the NIH Office of Dietary Supplements list possible interactions with:^[11][12]

• Thyroid hormone medications such as levothyroxine
• Diabetes medications
• Blood pressure medications
• Immunosuppressants
• Sedatives (including benzodiazepines) and anti-seizure medications

Avoid ashwagandha, or use it only with medical supervision, if you are pregnant or breastfeeding, have thyroid disease, an autoimmune condition, liver disease or hormone-sensitive prostate cancer, or have surgery scheduled.^[10][11]

How Ashwagandha Stacks With Other Nootropics

Ashwagandha And Rhodiola Together

Ashwagandha or rhodiola is a common question. Both are sold as adaptogens, but people typically reach for rhodiola rosea for daytime fatigue and ashwagandha for stress and sleep. They are often combined, though we are not aware of trials testing the pair together. Our full comparison is in ashwagandha vs rhodiola.

Ashwagandha And Tongkat Ali

Ashwagandha and tongkat ali are frequently paired in men’s products marketed for stress and testosterone. Neither combination has been studied as a stack, and both may affect hormones, so introduce them one at a time.

Ashwagandha With L-Theanine

L-theanine is a gentler, faster-acting option for daytime calm, while ashwagandha is taken daily for weeks. Some people use theanine during the day and ashwagandha in the evening. See our nootropic stacks guide for more combinations.

Where To Buy Ashwagandha

The best ashwagandha is one that names its extract, matches a studied dose and is independently tested. For a single-ingredient, standardized option, we point readers to Nootropics Depot, which publishes third-party testing for its extracts. On Amazon, buy only from listings that say “Sold by Nootropics Depot.”

Check Nootropics Depot Ashwagandha

Ashwagandha FAQs

Is KSM-66 The Best Ashwagandha?

KSM-66 has the most trials behind it, which makes it easy to dose to the research (300 mg twice daily). Shoden and Sensoril have smaller but positive evidence at lower doses.^[12] “Best” depends on matching the dose to the extract and buying a tested product.

How Long Does Ashwagandha Take To Work?

Most trials ran 8 to 10 weeks, and the sleep meta-analysis found stronger effects after at least eight weeks.^[5] Expect gradual changes rather than an effect from a single dose.

Can I Take Ashwagandha And Levothyroxine Together?

Only with your doctor’s approval. Ashwagandha can raise thyroid hormone levels, and NCCIH lists thyroid hormone medications as a possible interaction.^[8][11] If you combine them, your doctor may want to recheck thyroid levels.

Is Ashwagandha 300 Mg Enough?

One 300 mg dose of KSM-66 per day is half the most-studied dose. A 250 mg/day dose did reduce stress in one trial, but the 600 mg/day dose worked better and was linked to better sleep.^[3]

Should I Take Ashwagandha In The Morning Or At Night?

Trials typically split the dose twice daily. Because drowsiness is a possible side effect, many people take it, or at least the second dose, in the evening.^[11]

Why Is Ashwagandha Banned In Some Countries?

Denmark banned it in supplements in 2023 over concerns about pregnancy, thyroid and hormone effects, and France advised high-risk groups to avoid it in 2024.^[12] These were precautionary steps, not findings that it is unsafe for everyone.

What Is A Good Ashwagandha Alternative?

For stress and fatigue, rhodiola is the most common alternative; for calm without sedation, L-theanine; and for sleep, magnesium or apigenin-containing chamomile are gentler options. See our adaptogens guide.

References

1. Chandrasekhar K, et al. 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. PubMed
2. Lopresti AL, et al. An investigation into the stress-relieving and pharmacological actions of an ashwagandha (Withania somnifera) extract: a randomized, double-blind, placebo-controlled study. Medicine (Baltimore). 2019;98(37):e17186. PubMed
3. Salve J, et al. Adaptogenic and anxiolytic effects of ashwagandha root extract in healthy adults: a double-blind, randomized, placebo-controlled clinical study. Cureus. 2019;11(12):e6466. PubMed
4. Langade D, et al. Efficacy and safety of ashwagandha (Withania somnifera) root extract in insomnia and anxiety: a double-blind, randomized, placebo-controlled study. Cureus. 2019;11(9):e5797. PubMed
5. Cheah KL, et al. Effect of ashwagandha (Withania somnifera) extract on sleep: a systematic review and meta-analysis. PLoS One. 2021;16(9):e0257843. PubMed
6. Akhgarjand C, et al. Does ashwagandha supplementation have a beneficial effect on the management of anxiety and stress? A systematic review and meta-analysis of randomized controlled trials. Phytother Res. 2022;36(11):4115-4124. PubMed
7. Auddy B, et al. A standardized Withania somnifera extract significantly reduces stress-related parameters in chronically stressed humans: a double-blind, randomized, placebo-controlled study. Journal of the American Nutraceutical Association. 2008. OpenAlex record
8. Sharma AK, et al. Efficacy and safety of ashwagandha root extract in subclinical hypothyroid patients: a double-blind, randomized placebo-controlled trial. J Altern Complement Med. 2018;24(3):243-248. PubMed
9. Björnsson HK, et al. Ashwagandha-induced liver injury: a case series from Iceland and the US Drug-Induced Liver Injury Network. Liver Int. 2020;40(4):825-829. PubMed
10. LiverTox: Clinical and Research Information on Drug-Induced Liver Injury. Ashwagandha. National Institute of Diabetes and Digestive and Kidney Diseases. Updated December 3, 2024. NCBI Bookshelf
11. National Center for Complementary and Integrative Health. Ashwagandha. NCCIH
12. NIH Office of Dietary Supplements. Ashwagandha: Is It Helpful for Stress, Anxiety, or Sleep? Fact Sheet for Health Professionals. NIH ODS
13. Cadegiani FA, et al. Adrenal fatigue does not exist: a systematic review. BMC Endocr Disord. 2016;16(1):48. PubMed