What are the side effects of Ashwagandha?

Mild GI upset Drowsiness or sedation Rare but documented liver injury, including fatal cases in people with pre-existing liver disease

Who should avoid Ashwagandha?

Pregnant or breastfeeding Any pre-existing liver condition: avoid given documented cases of serious, sometimes fatal, liver injury Thyroid disorders without review Autoimmune conditions or before surgery without review

Adaptogen

Ashwagandha

A calming adaptogen with solid human evidence for reducing stress, anxiety, and cortisol at 300–600 mg/day of standardized extract. Any cognitive benefit is mostly downstream of stress relief and is still emerging in healthy adults.

Grade CUpdated September 17, 2026Written and fact-checked in-house against The Evidence Standard. Not a clinical review.

Photo by Bankim Desai on Unsplash

Please note

Educational content, not medical advice. Doses below are ranges used in research, not recommendations. Talk to a qualified clinician before starting any supplement, especially if you take medication, are pregnant, or manage a health condition.

Evidence grade: Evidence: Grade C
Studied dose range: 300–600 mg/day standardized root extract (KSM-66 ≥5% withanolides; Sensoril 125–250 mg at ≥10% withanolide glycosides).
Time to effect: Cumulative: builds over roughly 4–8 weeks.
Best form: KSM-66 (root-only, largest trial base) or Sensoril (higher withanolide load at a lower dose).

The short answer

Ashwagandha (Adaptogen) is studied for resilience to everyday stress and calm, non-stimulant focus under pressure. In our conservative reading of the published human research, the evidence is Grade C (limited). 300–600 mg/day standardized root extract (KSM-66 ≥5% withanolides; Sensoril 125–250 mg at ≥10% withanolide glycosides). Cumulative: builds over roughly 4–8 weeks. A studied dose is what trials used, not a recommended dose.

Full profile

Also known as	Withania somnifera, KSM-66, Sensoril
Best for	Resilience to everyday stress · Calm, non-stimulant focus under pressure · Sleep quality and next-day clarity
Evidence grade	Grade C · Limited: early or small human trials
Studied dose range	300–600 mg/day standardized root extract (KSM-66 ≥5% withanolides; Sensoril 125–250 mg at ≥10% withanolide glycosides).
Time to effect	Cumulative: builds over roughly 4–8 weeks.
Best form	KSM-66 (root-only, largest trial base) or Sensoril (higher withanolide load at a lower dose).

Evidence, honestly graded

60-day RCTs of 240–600 mg/day KSM-66 lowered perceived stress and serum cortisol versus placebo (Salve 2019; Lopresti 2019); direct cognition signals come from smaller trials and are not yet robust in healthy adults. Stress evidence is roughly B; the cognition grade is honestly C. Re-examined 2026-09-17: an independent GRADE-assessed meta-analysis of 20 RCTs in 1,249 adults (Zhu 2026) now reports consistent gains across memory, attention and processing speed, executive function and visuospatial ability, with low heterogeneity, a stronger cognition base than this profile previously had. It does not move the grade, because the cap here is a safety signal, not the efficacy data. A liver-safety signal caps the grade regardless of the stress-efficacy data: NIH LiverTox classifies ashwagandha as a "likely" cause of clinically apparent liver injury (likelihood score B), a 2023 case series documented ashwagandha-related liver injury, including deaths, in patients with underlying liver disease, and Australia's TGA issued a liver-safety alert in February 2024. A 1,002-person, 8-week randomized safety trial published in 2026 (Pakhale et al.) found no change in liver-function tests and fewer adverse events than placebo, which is reassuring about ordinary short-term use but does not test the rare, idiosyncratic injury the LiverTox rating and the TGA alert describe.

See the full grading rubric (study type, replication, population match, and dose adequacy) in The Evidence Standard.

2,172 natural health products with an active licence in Health Canada's LNHPD list Ashwagandha as a medicinal ingredient.

That makes Ashwagandha a recognized, licensable medicinal ingredient in Canada, regulated by Health Canada's Natural and Non-prescription Health Products Directorate, which issues each licensed natural health product a Natural Product Number (NPN). Search the LNHPD to verify.

Source: Health Canada Licensed Natural Health Products Database, snapshot 2026-09-28. A count of products with an active licence, not an endorsement of any health claim. This describes the ingredient's regulatory standing in Canada, not Signal State Core, which is a pre-launch concept and is not a licensed natural health product.

Side effects

Mild GI upset
Drowsiness or sedation
Rare but documented liver injury, including fatal cases in people with pre-existing liver disease

The full side-effect breakdown: Ashwagandha Side Effects: What the Research Actually Shows.

Who should avoid it or check first

Pregnant or breastfeeding
Any pre-existing liver condition: avoid given documented cases of serious, sometimes fatal, liver injury
Thyroid disorders without review
Autoimmune conditions or before surgery without review

Interactions

May interact with thyroid medication, sedatives, immunosuppressants, and blood-pressure or diabetes medication; discuss with a clinician

Stacks well with

Use caution stacking with

Rhodiola Rosea (activating adaptogen; a directional mismatch with ashwagandha's calming profile)

What to look for on a label

Health Canada permits adaptogen/stress and traditional-use wording; a modern focus/clarity claim is off-monograph.
Carry a liver-precaution line and a pre-existing-liver-disease avoidance statement. The safety signal is now documented by a regulator (TGA) and a published case series, not just a general monograph note.

References

Salve 2019, Cureus: KSM-66 stress/cortisol RCT. Reduced perceived stress and serum cortisol vs placebo in healthy adults. PMID 32021735; doi:10.7759/cureus.6466. Educational, not a product claim.
Lopresti 2019, Medicine (Baltimore): ashwagandha stress RCT. Stress-relief and cortisol reduction over 60 days. PMID 31517876; doi:10.1097/MD.0000000000017186. Educational, not a product claim.
LiverTox: Ashwagandha (NIDDK, updated 2024). Classifies ashwagandha as a likely cause of clinically apparent liver injury (likelihood score B). Basis for the liver-precaution line. NCBI Bookshelf NBK548536.
Case series: ashwagandha-associated liver injury (2023). Published case series in Hepatology Communications documenting ashwagandha-related liver injury, including deaths, in patients with underlying liver disease. Basis for the pre-existing-liver-disease avoidance statement. PMID 37756041. Educational, not a product claim.
TGA safety alert: ashwagandha and liver injury (February 2024). Australia's Therapeutic Goods Administration issued a liver-safety alert for ashwagandha-containing products. tga.gov.au.
Zhu X, Zeng Q, Lei Y, Xu D (2026). Frontiers in Pharmacology, 17:1799467GRADE-assessed systematic review and meta-analysis, 20 RCTs, 1,249 adultsMemory SMD 0.52, attention and processing speed 0.29, executive function 0.42, visuospatial ability 0.39, with low heterogeneity across the memory and attention pools.
Pakhale K, Salve J, Ademola J, et al. (2026). Phytotherapy Research, 40(8):5005–5015Randomized, double-blind, placebo-controlled multicentre safety trial, n=1,002 adults aged 18–65, 8 weeksStudied dose: 600 mg/day of root extract in two divided dosesNo significant change in liver, kidney or haematological laboratory parameters; 5.6% of the extract group reported adverse events versus 9.2% on placebo; no serious adverse events.

Entries above without a linked identifier are either editorial summaries of a wider body of literature or references to a named authority (a regulator or government monograph) cited by name rather than by a single paper.

Grades and studied doses are our conservative reading of the human research, shown for education. They are not product claims, and a studied dose is not a recommended dose.

Revision history

Every change to this ingredient's evidence status, dated and explained. The full cross-library log lives at Evidence Updates.

2026-09-17Safety note
Added the two largest pieces of new evidence and kept the grade where it is. An independent meta-analysis of 20 trials in 1,249 adults now reports consistent cognitive gains across memory, attention, executive function and visuospatial ability, which is a stronger efficacy base than this profile had. A 1,002-person, 8-week randomized safety trial found no change in liver-function tests and fewer adverse events than placebo. Neither moves the grade: the cap here is the LiverTox rating and the TGA alert, and an 8-week trial does not test the rare idiosyncratic injury they describe.
2026-07-07New profile
Initial profile published at Grade C: 60-day RCTs lower perceived stress and cortisol, but direct healthy-adult cognition signals remain thin; the profile carries a liver-safety caution.

See how Ashwagandha compares on grade, dose, and goal in the Evidence Explorer.

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