An herb used in Ayurvedic medicine, studied mainly for stress, anxiety and sleep.
Evidence: Moderate
Evidence by use: Moderate for stress and sleep (short term). Studies report lower perceived stress and cortisol compared with placebo over 6-8 weeks. A meta-analysis found a small but significant improvement in sleep, more prominent at 600 mg per day for at least 8 weeks. Long-term safety is not known.
At a glance
Typical studied dose
Studies used 240-1,250 mg per day of root extract. NIH notes benefits appeared greater at 500-600 mg per day, over 6-8 weeks.
Food sources
Plant sources
The root and leaf of the ashwagandha plant (a supplement herb, not a food).
Background and testing
This is not an essential nutrient, so there is no deficiency to diagnose.
Good to know
People use it for stress, sleep and energy.
Who tends to use it
Adults with high stress or poor sleep who are not in the avoid groups.
How it is tested
No test for need. Clinicians may check liver enzymes or thyroid function if you take it with a condition or medicines.
Supplement forms
Common forms
Root extract capsules (often standardized to withanolides), root powder, tinctures, gummies. Common branded extracts include KSM-66 and Sensoril.
More effective
Standardized root extract with a stated withanolide percentage from a third-party-tested brand, used for a limited period.
Less effective
Unstandardized powders with unknown strength; leaf-heavy or untested products; long-term continuous use without a break or monitoring.
Safety, interactions and halal notes
Safety and interactions
Well tolerated up to about 3 months in studies; common effects are loose stools, nausea and drowsiness. Cases of acute liver injury have been reported at 450-1,350 mg per day (jaundice, nausea, elevated bilirubin). It may affect thyroid function and interact with thyroid, diabetes, blood-pressure, sedative and immunosuppressant medicines.
Who should avoid it or ask a clinician first
Pregnant and breastfeeding women; men with hormone-sensitive prostate cancer; people with liver disease, thyroid disorders, or those on the medicines above. Stop and seek care if you notice jaundice, dark urine or severe fatigue.
Halal note
Plant-based. Check the capsule (gelatin or vegetarian) and any carriers or flavorings, and ask for halal certification of the finished product.
Frequently asked questions
Does ashwagandha lower cortisol?
Several trials report lower cortisol and stress scores over 6-8 weeks compared with placebo. Study quality and product types vary.
Is ashwagandha safe long-term?
Long-term safety is not known, and liver injury and thyroid effects have been reported, so it is best used with a clinician's guidance.
This page is for education only and is not medical advice. These statements have not been evaluated by the Food and Drug Administration. Supplements are not intended to diagnose, treat, cure or prevent any disease. Talk to a qualified clinician before starting a supplement, especially if you are pregnant, breastfeeding, take medicine or have a medical condition. Daily needs are US reference intakes for adults 19-50.
