Ashwagandha: Benefits, Dosage, and Safety

What ashwagandha is

Ashwagandha is an evergreen shrub, Withania somnifera (L.) Dunal, cultivated in tropical and subtropical parts of Asia, Africa, and Europe. Its root has long been used in the traditional Ayurvedic and Unani medicine systems of India as an adaptogen, meaning a product said to help the body resist or adapt to biological, physical, or chemical stressors. Most commercial supplements use extracts from the root, though some use root and leaf. It is not a nutrient and is not part of the ginseng family despite the nickname Indian ginseng.

What it does

• Marketed as an adaptogen said to help the body resist and adapt to physical, chemical, and biological stress (a traditional-use concept, not an established nutrient function)
• Rich in phytochemicals, chiefly steroidal lactones called withanolides plus alkaloids, which are believed to drive many of its proposed effects
• Studied for effects on perceived stress, anxiety, and serum cortisol levels
• Studied for effects on sleep quality, sleep efficiency, total sleep time, and sleep latency

Intake and dosing

Ashwagandha is not an essential nutrient, so no Recommended Dietary Allowance or Tolerable Upper Intake Level has been set. Doses in studies vary widely. Because supplement doses are not standardised, discuss an appropriate amount with a clinician or pharmacist.

Deficiency and who is at risk

Not applicable. Ashwagandha is a botanical, not an essential nutrient, so there is no deficiency state, no Dietary Reference Intake, and no requirement for health.

Who may need more

• No one needs ashwagandha; it is not an essential nutrient and has no established requirement
• Adults with self-reported stress or anxiety are the group most studied, where extracts may modestly reduce perceived stress and anxiety
• Adults with insomnia or poor sleep, where benefits on sleep appeared more pronounced, especially at 600 mg/day for at least 8 weeks

Food sources

Not a dietary nutrient. Ashwagandha is consumed as the root or leaf of Withania somnifera, taken as extracts, powders, capsules, or granules rather than obtained from common foods.

Forms and absorption

Most supplements use root extract; some use root-and-leaf extract, and root and leaf differ in chemical composition. Products are often standardized to withanolide content and sold under proprietary names such as KSM-66 (root, standardized to more than 5% withanolides), Sensoril and Shoden (root and leaf), NooGandha, Prolanza, and Witholytin. Because extraction and standardization vary widely between products, doses and effects are not directly comparable across brands. Withanolides are believed to be the main active constituents, though non-withanolide components may also contribute.

Safety, excess and interactions

Too much

Ashwagandha appears well tolerated for up to about 3 months; long-term safety is unknown. Common side effects are usually mild and include upset stomach, loose stools, nausea, and drowsiness; increased heart rate variability has also been reported. More serious but uncommon reports include acute liver injury (jaundice, pruritus, nausea, lethargy, abdominal discomfort, hyperbilirubinemia), sometimes in people who took supplements containing 450 to 1,350 mg ashwagandha daily over 1 week to 4 months, and cases of thyrotoxicosis, including one at an unusually high dose of 1,950 mg/day for more than 2 months. Symptoms generally resolved after stopping the supplement.

Interactions to know

• Thyroid hormone medications: ashwagandha may affect thyroid function (small increases in T4 reported; lowered TSH and increased T3 and T4 in subclinical hypothyroidism), and cases of thyrotoxicosis have been reported, so it may interact with thyroid medications
• Antidiabetes medications: potential interaction (may affect blood glucose)
• Antihypertensive medications: potential interaction (may affect blood pressure)
• Immunosuppressants: potential interaction (ashwagandha may stimulate immune activity)
• Sedatives: potential additive interaction (ashwagandha can cause drowsiness)

How status is measured

Not routinely measured. There is no clinical lab marker for ashwagandha status because it is not an essential nutrient. In research, effects are gauged indirectly through validated stress, anxiety, and sleep rating scales, actigraphy, and serum or salivary cortisol. Given liver and thyroid safety signals, clinicians may monitor liver function tests and thyroid function (TSH, T3, T4) in people using it.

Sold in the United States as a dietary supplement under the Dietary Supplement Health and Education Act (DSHEA). It is not FDA-approved to prevent, treat, or cure any disease, and supplements are not reviewed by FDA for safety and effectiveness before marketing. Some countries have restricted it: Denmark banned ashwagandha in 2023, and France's ANSES advised against use in certain populations in 2024.

What the evidence supports

We grade the strength of evidence behind each common reason people take ashwagandha, mirroring how the NIH describes it.