Ashwagandha (KSM-66)
Overview
Ashwagandha (Withania somnifera) is an Ayurvedic adaptogenic herb. Its active compounds are withanolides. KSM-66 is a standardized root extract used in clinical trials for stress, anxiety, and sleep at 300–600 mg extract daily. Short-term use (up to 3 months) is considered well tolerated. Reports of liver injury exist with prolonged use. Avoid during pregnancy. Contraindicated in autoimmune diseases and hormone-sensitive cancers. May interact with thyroid and immunosuppressant medications.
Dosage
600 mg · Evening · Take with food
Key Interactions
22 verified interactions found
Both have sedative properties. Ashwagandha via GABAergic action, Melatonin via MT1/MT2 receptors. Combined use may cause excessive drowsiness in sensitive individuals.
Start with low doses of both. Take together only at bedtime. Monitor for excessive sedation.
View details →Both have sedative and anxiolytic properties. Ashwagandha via GABAergic modulation, CBD via endocannabinoid and serotonin receptor (5-HT1A) agonism. Combined sedation risk.
Start with low doses of each. Monitor for excessive sedation, especially in the evening.
View details →Ashwagandha supports energy via stress reduction; B12 is a cofactor for energy metabolism. Together they combat fatigue.
Combine for energy.
View details →Ashwagandha reduces cortisol; Magnesium supports GABA receptor function and muscle relaxation. Complementary pathways for stress and sleep support.
Combine freely. Both can be taken in the evening for sleep support.
View details →Both are adaptogens acting on the HPA axis. Ashwagandha primarily lowers cortisol (GABA-mimetic), Rhodiola enhances stress tolerance via monoamine modulation. Complementary mechanisms without antagonism.
Can combine safely. Ashwagandha evening, Rhodiola morning for circadian alignment.
View details →What Experts Say
“if you look at the literature on ashwagandha, you will see that indeed it can be effective in reducing cortisol levels by anywhere from about 11% to 29%”
Huberman identifies ashwagandha as the most evidence-backed supplement for reducing cortisol, with studies showing 11–29% reductions. He recommends taking it only in the evening (not morning, when cortisol should be high), starting at 300 mg, and cycling off after prolonged use to avoid suppressing baseline cortisol.
Scientific Sources
- NIH Office of Dietary Supplements
- National Center for Complementary and Integrative Health
- PubChem CID 265237
- PubMed Batch-02
- PubMed Batch-02
- Ashwagandha sleep-promoting effects
- Melatonin receptor pharmacology
- CBD anxiolytic mechanisms
- Thyroid, diet, and alternative approaches — B12 + adaptogen context (2022)
- OTC supplements for memory incl. B-vitamins + adaptogens (2023)
- B12 energy metabolism and fatigue (2008)
- Clinician guidelines nutraceuticals for psychiatric disorders (2022)
- Testosterone boosters review incl. Ashwagandha + minerals (2024)
- Withania + magnesium related study (2025)
- Nootropic herbs and cognitive enhancers review (2023)
- Adaptogens on depression — systematic integrative review (2023)
- Adaptogenic herbs mechanisms and clinical evidence (2020)
Frequently Asked Questions
What is Ashwagandha (KSM-66) used for?
Ashwagandha (Withania somnifera) is an Ayurvedic adaptogenic herb.
What is the recommended dosage for Ashwagandha (KSM-66)?
600 mg. Evening. Take with food.
Does Ashwagandha (KSM-66) interact with other supplements?
Ashwagandha (KSM-66) has 22 verified interactions. Top: Melatonin, CBD (Cannabidiol).
When is the best time to take Ashwagandha (KSM-66)?
Evening. Take with food.
Is Ashwagandha (KSM-66) safe to combine with other supplements?
Always check interactions before combining supplements. Use VitalStack to verify your full stack for free.
Check how Ashwagandha (KSM-66) fits your full stack
Verify interactions, get timing plans, and optimize your supplement routine — free.
Check Your Stack →Not medical advice. VitalStack is not a medical device. For personalized health recommendations, consult a healthcare provider.