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AdaptogenClinical dose · 300–600mg/day (KSM-66 extract)Onset · Stress and cortisol effects measured at 60 days; memory effects at 8 weeks (MCI trial)

Ashwagandha (KSM-66)

A 2012 RCT in chronically stressed adults (Chandrasekhar et al., KSM-66 600mg/day, 60 days; extract supplied by its maker Ixoreal Biomed) found serum cortisol fell 27.9% versus 7.9% on placebo and perceived stress fell 44%. A 2024 meta-analysis of 9 RCTs confirmed significant reductions in perceived stress, anxiety and cortisol, though a 2019 crossover trial of a low-dose extract in older overweight men found no cortisol effect. A 2017 RCT (Choudhary et al., 300mg twice daily, 8 weeks) improved memory and executive function — in adults with mild cognitive impairment, not healthy adults. Liver-injury case reports exist, and Denmark banned ashwagandha supplements in 2023.

By The Nootropic Lab editorial teamUpdated 8 min read✓ Fact-checked

Evidence reviewed:

Mechanism of action

Ashwagandha (Withania somnifera) is an Ayurvedic adaptogen. Its withanolides modulate the HPA axis to reduce cortisol, while also inhibiting acetylcholinesterase (preserving acetylcholine) and promoting GABA receptor activity for anxiolytic effects. KSM-66 is a full-spectrum root extract.

Clinical evidence summary

A 2012 RCT in chronically stressed adults (Chandrasekhar et al., KSM-66 600mg/day, 60 days; extract supplied by its maker Ixoreal Biomed) found serum cortisol fell 27.9% versus 7.9% on placebo and perceived stress fell 44%. A 2024 meta-analysis of 9 RCTs confirmed significant reductions in perceived stress, anxiety and cortisol, though a 2019 crossover trial of a low-dose extract in older overweight men found no cortisol effect. A 2017 RCT (Choudhary et al., 300mg twice daily, 8 weeks) improved memory and executive function — in adults with mild cognitive impairment, not healthy adults. Liver-injury case reports exist, and Denmark banned ashwagandha supplements in 2023.

Human effect matrix

Based on human clinical trials only. Animal and in-vitro data excluded.

EffectEvidenceMagnitudeStudies
Cortisol Reduction strong
Large
3
Anxiety & Stress strong
Large
2
Sleep Quality moderate
Moderate
—
Memory (Mild Cognitive Impairment) preliminary
Moderate
1

Evidence key: Strong = multiple consistent RCTs · Moderate = smaller/fewer RCTs · Preliminary = early trials or small n · Mixed = conflicting results

Documented benefits

  • Cortisol reduction
  • Lower perceived stress and anxiety
  • Memory in mild cognitive impairment (one 8-week RCT)
  • Sleep quality
  • Muscle strength and recovery

Side effects & cautions

  • Generally well tolerated in 8–12 week trials
  • GI upset in some users
  • Liver injury: published case reports and case series, including cases scored "probable" on the RUCAM causality scale that resolved after stopping — stop and see a doctor if you notice jaundice or dark urine
  • Denmark banned ashwagandha food supplements in 2023 because a safe dose could not be established
  • Contraindicated in thyroid conditions
  • Avoid during pregnancy

How to take

Dosage300–600mg/day (KSM-66)
TimingEvening (1–2 hours before bed) for sleep benefits. Morning for cortisol and stress management. Split dosing (300mg AM + 300mg PM) is the regimen of the Chandrasekhar 2012 and Choudhary 2017 trials (300mg twice daily).
With foodTake with food to minimise GI upset (particularly with 600mg doses). Absorption is not significantly affected by food.
FormsCapsule. Choose an extract that states its withanolide content. The trials on our ashwagandha page used a high-concentration full-spectrum root extract (Chandrasekhar 2012), a root extract (Choudhary 2017) and the Shoden extract (Lopresti 2019); we cite no Sensoril trial. Avoid unstandardised ashwagandha with no withanolide percentage stated — active content may be negligible.

Stacking recommendations

Ingredients that pair well with Ashwagandha (KSM-66) and why.

Rhodiola Rosea

Both are adaptogens; we cite no trial of the pairing.

L-Theanine

Both are studied for anxiety and stress; we cite no trial of the pairing.

Phosphatidylserine

We cite no trial of the pairing.

Frequently asked questions

KSM-66 vs Sensoril vs generic ashwagandha — which should I choose?

Choose an extract that states its withanolide content. The trials on our ashwagandha page used a high-concentration full-spectrum root extract (Chandrasekhar 2012), a root extract (Choudhary 2017) and the Shoden extract (Lopresti 2019); we cite no Sensoril trial. Generic ashwagandha without a stated withanolide percentage is unreliable — you may be paying for starchy root powder with minimal active content.

Will ashwagandha make me tired during the day?

The tiredness effect is most pronounced when taken at night, where it reduces sleep latency. Ashwagandha doesn't deplete energy. Some people find 600mg in the morning slightly sedating — if so, reduce to 300mg or shift to evening only.

Is ashwagandha safe for long-term use?

Long-term data is missing: most trials run 8–12 weeks, and no controlled safety data beyond about 90 days was found. Published case reports link ashwagandha to liver injury (some scored "probable" on the RUCAM causality scale), and Denmark banned ashwagandha food supplements in 2023 because a safe dose could not be established. Stop and see a doctor if you develop jaundice or dark urine. Avoid if you have thyroid conditions (autoimmune thyroid disease) as withanolides can modulate thyroid hormone levels.

Can ashwagandha increase testosterone?

Two RCTs found increases: 600mg/day for 8 weeks in young men starting resistance training raised testosterone alongside greater strength gains (2015), and a crossover trial in overweight men aged 40–70 found testosterone +14.7% and DHEA-S +18% versus placebo — but no change in cortisol, fatigue or vigour (Lopresti 2019). The magnitude varies by population and extract.

Top stacks containing Ashwagandha (KSM-66)

Thesis

7/10

Take Thesis

Ashwagandha (KSM-66) in the Gulf

Products in the Gulf

SFDA / Dubai Municipality

GCC country guides

Regulatory note

Dietary supplements sold in Saudi Arabia are regulated by the Saudi Food and Drug Authority (SFDA); in the UAE, general food supplements are regulated by Dubai Municipality while products making medicinal or therapeutic claims require marketing authorisation from the Emirates Drug Establishment (EDE, ede.gov.ae), which now handles drug registrations previously processed through the Ministry of Health and Prevention (MOHAP). Many GCC consumers prefer Halal-certified supplements; capsule shells (gelatin vs HPMC vegetable cellulose) are a meaningful differentiator. We surface Halal-certifying authority where verifiable and never fabricate certifications. This page is editorial, not medical advice. Always consult a qualified healthcare professional before starting any supplement.

Sources (8)expand
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