Ashwagandha Supplements: Benefits, Side Effects and Dosage
Ashwagandha is a traditional Ayurvedic herb. Small trials suggest it can lower stress scores and may improve sleep when taken for 6–8 weeks at 300–600 mg a day. It's usually well tolerated, but rare liver injury has been reported, and it isn't suitable during pregnancy or for people with thyroid conditions.
Evidence at a glance
| Use | Grade | What the research shows |
|---|---|---|
| Perceived stress | B | Several small randomized trials show lower stress scores than placebo. |
| Sleep quality | C | Some trials show improvement; studies are small and short. |
| Anxiety | C | Promising but limited and partly industry-funded evidence. |
| Testosterone and fertility in men | C | Small trials report increases; needs confirmation. |
A: strong, consistent human evidence · B: moderate · C: limited or mixed · D: good evidence of no benefit.
Ashwagandha has been used in Ayurvedic medicine for centuries and is now one of the best-selling herbal supplements. It's called an "adaptogen," a term for herbs thought to help the body handle stress, though that's a traditional idea rather than a defined medical category.
What the research shows
Most human trials used root extracts for 6–12 weeks in adults reporting stress. Several found lower stress and anxiety scores and, in some, lower cortisol compared with placebo. The trials are generally small and short, and some were funded by extract makers, so the evidence is promising but not definitive.
Choosing a product
- Prefer root extracts with the withanolide content listed
- Branded extracts such as KSM-66 and Sensoril have their own trials, at different doses
- Look for third-party testing for purity
If you're deciding between adaptogens, see ashwagandha vs rhodiola.
Side effects and who should avoid it
Common side effects include drowsiness and stomach upset. Rare cases of liver injury have been reported; stop and see a doctor if you notice yellow skin or eyes or dark urine. Avoid it during pregnancy and breastfeeding, and talk to a doctor first if you have a thyroid or autoimmune condition, or take sedatives, thyroid medication, immunosuppressants, or diabetes or blood pressure drugs.
Sources
This page is for education and is not a substitute for advice from your doctor. Read our medical disclaimer.