Most clinical trials use between 250 and 600 mg per day of ashwagandha root extract, typically split into two doses. That range covers the majority of studied benefits, from stress reduction to better sleep. But the right number for you depends on what form you’re taking, because raw root powder and concentrated extracts are very different products with very different dosing.
Extract vs. Root Powder: Why the Mg Matters
The single biggest factor in choosing your dose is whether you’re taking a concentrated extract or plain root powder. Extracts pull out and concentrate the active compounds (called withanolides), so you need far less material to get the same effect. Root powder is the whole dried root, ground up, with a much lower concentration of those active compounds per gram.
For root extract, the typical range in clinical research is 250 to 600 mg per day. For raw root powder, the equivalent dose jumps to 3 to 6 grams per day (3,000 to 6,000 mg). Some fertility studies have used as much as 5 grams of root powder daily. If you’re comparing products, always check the supplement facts panel for whether the capsule contains an extract or plain powder, because 500 mg of extract is not the same as 500 mg of powder.
Common Doses by Goal
Stress and Anxiety
A systematic review of seven clinical trials on stress and anxiety used ashwagandha extract doses ranging from 240 to 1,250 mg per day. The most commonly studied dose in this space is 300 mg of root extract taken twice daily (600 mg total), which is the protocol used in several well-known trials. If you’re trying ashwagandha primarily for stress, 300 to 600 mg per day of a standardized root extract is the range with the most supporting evidence.
Sleep
Sleep studies have used a similar dosing pattern: 600 mg per day of root extract, split into two 300 mg capsules. These trials included both healthy adults and people with insomnia. The extract used was standardized to contain more than 5% withanolides per capsule, which is worth checking on any product label since not all extracts are equally concentrated.
Muscle Strength and Testosterone
For physical performance, the most cited trial gave young men 300 mg of root extract twice daily (600 mg total) alongside an 8-week resistance training program. The ashwagandha group showed greater increases in both testosterone and strength compared to the placebo group. A separate trial in overweight older men used a lower dose of a highly concentrated extract (standardized to deliver 21 mg of withanolide glycosides per day) and still saw results over 8 weeks. For fertility specifically, several studies used 5 grams of root powder per day, a much higher dose but of the less concentrated form.
KSM-66 vs. Sensoril
These are the two branded extracts you’ll see most often on supplement labels, and they’re made differently. KSM-66 is a root-only extract standardized to more than 5% withanolides. It’s the most widely studied form, with clinical doses typically between 250 and 600 mg per day. Sensoril is made from both root and leaf, which gives it a different withanolide profile. It has been studied at various doses within the broader 240 to 1,250 mg range.
Because the concentration of active compounds differs between these extracts, you can’t simply swap one for the other at the same milligram dose and expect identical results. If you’re switching brands, check both the extract type and the withanolide percentage listed on the label.
How Long Before You Notice Anything
Ashwagandha is not a fast-acting supplement. Most clinical trials measure outcomes at the 8-week mark, and that’s a reasonable timeframe to expect before judging whether it’s working for you. Some people report subtle changes in sleep quality or stress levels within the first few weeks, but the meaningful, measurable effects in studies tend to show up after consistent daily use for at least two months.
Side Effects and Who Should Be Cautious
At the doses used in clinical trials (up to about 600 mg of extract per day), ashwagandha is generally well tolerated. The most commonly reported side effects are mild: stomach upset, drowsiness, and loose stools. Higher doses, particularly of raw powder in the multi-gram range, are more likely to cause digestive discomfort.
Ashwagandha can affect thyroid hormone levels, which makes it a concern if you take thyroid medication like levothyroxine. The interaction is rated as moderate, meaning it could change how well your thyroid medication works. If you have a thyroid condition, whether overactive or underactive, this is a supplement to discuss with your doctor before starting.
Pregnant and breastfeeding women are typically advised to avoid ashwagandha, as safety data for those populations is limited. People taking immunosuppressants or sedatives should also use caution, since ashwagandha may amplify the effects of both.
Picking a Practical Starting Dose
If you’re using a standardized root extract (KSM-66 or similar with at least 5% withanolides), 300 mg once or twice a day is the best-supported starting point. That gives you a daily total of 300 to 600 mg, which falls squarely within the range used in the largest body of clinical research. Many people take one capsule in the morning and one in the evening, though the studies don’t consistently show that timing matters.
If you prefer root powder (in smoothies, for example), aim for 3 to 6 grams per day. Keep in mind that powder is harder to dose precisely and has a strong, earthy, slightly bitter taste that most people find unpleasant on its own.
There’s no established upper safety limit from regulatory authorities, but clinical trials rarely exceed 1,250 mg per day of extract. Staying at or below 600 mg of a standardized extract keeps you in the range where both benefits and safety have been most thoroughly studied.