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ingestible · for low energy & fatigue

Ashwagandha (KSM-66)

Reviewed by the Nimbera editorial team · Last updated May 2026

Sandhu et al. 2023 RCT (Medicine, PMID 37740662) - 60 adults with chronic fatigue taking KSM-66 ashwagandha 300 mg twice daily for 8 weeks showed significant improvements in fatigue (FSS score) vs placebo (p < 0.001), with improvements in perceived stress, sleep quality, and cortisol levels.$20-$35/month.

How to use

Take 300-600 mg/day of KSM-66 ashwagandha extract (standardised to 5% withanolides) with food. Split into two 300 mg doses or take once daily. Allow 4-8 weeks for full adaptogenic benefit.

How it works

Withanolides modulate the HPA axis stress response, reducing chronic cortisol elevation that impairs energy metabolism and sleep quality. Ashwagandha also enhances mitochondrial oxygen consumption, supports thyroid hormone conversion (T4 to T3), and reduces neuroinflammation - all contributing to sustained energy improvement.

Where to buy

KSM-66 Ashwagandha by Ixoreal ($20-$30/60 capsules), Jarrow Formulas Ashwagandha KSM-66 ($20-$28/120 capsules), Thorne Botanicals Ashwagandha ($25-$35) - look specifically for KSM-66 or Sensoril branded extracts.

Typical cost: $20-$35/month.

Safety notes

Avoid in pregnancy (potential uterotonic effects at high doses). May increase thyroid hormone levels - use caution in hyperthyroidism or if on thyroid medications (monitor levels). Rare: liver injury reported at very high doses with some products - stick to standardised, reputable brands. May cause drowsiness in some people - take at night if this occurs. Avoid with sedative medications (additive CNS depression).

Drug & supplement interactions

  • Always tell your doctor or pharmacist about any supplements you take.
  • Interactions can occur with prescription medications, blood thinners, and immunosuppressants.
  • Herbal remedies can affect how the body absorbs or metabolises drugs.
  • Check drugs.com interactions checker before starting.

Clinical source

Sandhu et al. 2023 - Medicine (PMID 37740662)

This information is compiled from primary clinical literature and is for informational purposes only. It is not a substitute for professional medical advice. Read our full disclaimer.