Most clinical trials use between 300 and 600 mg of ashwagandha root extract per day, typically split into two doses. The right amount for you depends on the type of extract and what you’re taking it for, since concentrated formulas deliver the same active compounds in much smaller capsules than standard root extracts.
Dosage by Goal
The dose that showed up most often in human studies is 600 mg per day of a root extract (like KSM-66), taken as two 300-mg capsules. That said, different goals have been tested at slightly different amounts.
For sleep: A meta-analysis of five trials found that ashwagandha had a small but significant benefit for sleep quality compared to placebo. The effect was strongest at 600 mg per day of root extract, taken for at least 8 weeks. One study used a more concentrated root-and-leaf extract (Shoden) at just 120 mg per day, split into two 60-mg capsules, and still showed improvements. The difference comes down to how much of the active compounds, called withanolides, each formula contains. The concentrated extract packed about 21 mg of withanolide glycosides into each tiny 60-mg capsule, while standard root extracts contain around 5% withanolides by weight.
For strength and exercise performance: A systematic review of athletic performance studies found that 300 to 500 mg of root extract per day, taken in two doses for 8 to 12 weeks, improved cardiorespiratory fitness, muscle strength, and recovery. In one 8-week trial, people taking 300 mg twice daily (600 mg total) saw their bench press strength nearly double compared to placebo, along with measurable gains in arm muscle size. A separate trial found that 500 mg per day improved both upper and lower body strength over 12 weeks.
For stress and general well-being: Most trials in healthy, stressed adults have used 300 to 600 mg per day of root extract, run over 6 to 12 weeks.
Extract Type Changes the Dose
This is the part that trips people up. Not all ashwagandha supplements are comparable milligram-for-milligram, because extracts vary in how concentrated they are. The three forms you’ll commonly see on labels work quite differently.
- Root extract (e.g., KSM-66): Standardized to at least 5% withanolides. Typical dose is 300 mg taken twice daily (600 mg total).
- Root and leaf extract (e.g., Sensoril, Shoden): Higher withanolide concentration, so the effective dose is lower. Shoden, for example, was used at just 120 mg per day in clinical trials.
- Plain root powder: The least concentrated form. You’d need considerably more, often 1,000 to 2,000 mg or higher, to match the withanolide content of a standardized extract. Most clinical evidence is based on extracts, not raw powder.
Check your supplement label for the extract type and withanolide percentage. A product listing “ashwagandha root powder” in a 500-mg capsule is not the same as one listing “ashwagandha root extract (5% withanolides)” at 300 mg.
When to Take It
There is no single best time of day to take ashwagandha. Some trials had participants take it after dinner, others split the dose between morning and evening. No head-to-head study has compared morning versus nighttime dosing. If you’re using it primarily for sleep, taking it in the evening makes intuitive sense. If you’re splitting the dose into two capsules, morning and evening is the most common schedule used in research. Taking it with food can help reduce the occasional stomach discomfort some people report.
How Long Before It Works
Ashwagandha is not something you feel after a single dose. The trials that showed benefits ran for a minimum of 6 weeks, and the strongest results for sleep came at 8 weeks or longer. For strength gains, studies lasted 8 to 12 weeks. Plan on at least 6 to 8 weeks of consistent daily use before judging whether it’s helping.
Safety and Side Effects
In clinical trials lasting up to 12 weeks, doses of 120 to 600 mg per day of ashwagandha extract were generally well tolerated. The most common side effects are mild: upset stomach, drowsiness, and loose stools. Beyond 12 weeks, there’s limited safety data simply because most studies haven’t run longer than that.
Several groups should avoid ashwagandha entirely. It should not be used during pregnancy or while breastfeeding. People with autoimmune conditions or thyroid disorders are advised against it, since ashwagandha can stimulate thyroid hormone production and may rev up immune activity. Those with hormone-sensitive prostate cancer should also skip it, because ashwagandha can raise testosterone levels.
Ashwagandha can interact with medications for diabetes, high blood pressure, seizures, and thyroid conditions. It may also amplify the effects of sedatives and drugs that suppress the immune system. If you take any of these, check with your pharmacist or doctor before adding ashwagandha to your routine. People scheduled for surgery should stop taking it beforehand, as it may affect sedation and blood pressure during the procedure.