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KSM-66 Ashwagandha

Also known as: Withania somnifera, Indian ginseng, winter cherry, ashwagandha root extract

Evidence under review. — Not yet rated

Adaptogenic herb. Widely studied for stress relief, cortisol reduction, and sleep support.

  • What it does

    KSM-66 is a branded, full-spectrum ashwagandha root extract standardized to at least 5% withanolides — the active compounds believed to drive its effects. It is one of the most researched forms of...

  • Evidence quality

    Evidence base hasn't been formally rated yet. See research below.

  • Clinical dose

    300-600 mg daily (root extract, standardized to ≥5% withanolides)

  • Found in

    WeightWorld Ashwagandha KSM-66 Tablets, BrainMD Stress Relief Sleep, Calm My Brain and 4 more

See full breakdown ↓ Methodology →

What the Science Says

KSM-66 is a branded, full-spectrum ashwagandha root extract standardized to at least 5% withanolides — the active compounds believed to drive its effects. It is one of the most researched forms of ashwagandha and is commonly used to help the body manage stress, reduce perceived anxiety, and support sleep quality. Typical doses range from 300–600 mg daily, with most people reporting noticeable effects after 4–8 weeks of consistent use.

What It Doesn't Do

Won't replace prescription anxiety or sleep medication. Not a testosterone booster in healthy men with normal levels. Won't build muscle on its own without exercise. No solid evidence it directly burns fat or boosts metabolism. 'Clinically proven' marketing often overstates effect sizes from small studies.

Evidence-Based Benefits

Reduces perceived stress and lowers cortisol levels in chronically stressed adults.

Moderate Evidence

Effective at: 300-600 mg daily

Improves sleep onset and overall sleep quality in adults with mild insomnia.

Moderate Evidence

Effective at: 300-600 mg daily

Reduces self-reported anxiety symptoms in adults under chronic stress.

Moderate Evidence

Effective at: 300-600 mg daily

May modestly improve muscle strength and recovery when combined with resistance training.

Weak Evidence

Effective at: 600 mg daily

Absorption & Bioavailability

Moderate — fat-soluble withanolides absorb better when taken with food containing some fat. KSM-66's full-spectrum extraction is designed to preserve the natural root profile, which may improve absorption compared to isolated extracts.

Red Flags to Watch For

  • Rare but reported cases of liver injury linked to ashwagandha supplements — discontinue if you notice yellowing of skin or eyes
  • May interact with thyroid medications — ashwagandha can influence thyroid hormone levels
  • Avoid during pregnancy — traditional use and some animal data suggest it may stimulate uterine contractions
  • Products claiming KSM-66 but not listing the standardized withanolide percentage may be using inferior or mislabeled extract
  • Many 'KSM-66' products underdose below the 300 mg threshold used in most clinical research

Products Containing KSM-66 Ashwagandha

See how KSM-66 Ashwagandha is used in these analyzed products:

WeightWorld Ashwagandha KSM-66 Tablets

Supplement

Mostly Legit

BrainMD Stress Relief Sleep

Supplement

Mostly Legit

Calm My Brain

Supplement

Mostly Legit

Lemme Chill Ashwagandha Gummies

Supplement

Overhyped

Eversmithorganics

Supplement

Overhyped

BPI Sports Best Test 120 Tablets

Supplement

Misleading

TestoPrime

Supplement

Misleading
View all product reviews →

Research Sources

  • General knowledge — no papers were provided for this analysis. Claims reflect the broader published literature on KSM-66 ashwagandha but have not been verified against specific provided abstracts. Treat evidence ratings as conservative estimates.

This information is for educational purposes only and is not medical advice. Always consult a healthcare professional before starting any supplement regimen. Last updated: 2026-05-25