Ashwagandha (Withania somnifera) is a shrub whose roots are often used in traditional Ayurvedic medicine to help people feel calm and strong. The name "ashwagandha" means "smell of horse," which refers to the root's smell. The species name "somnifera" means "sleep-inducing," which is what it was traditionally used for. 

Ayurveda calls ashwagandha an adaptogen, which is a natural substance that is thought to help the body deal with stress and bring things back into balance. Today, ashwagandha is often sold in the West as a way to reduce stress, anxiety, and improve sleep (nccih.nih.gov).

Researchers have been looking into ashwagandha in clinical trials to see if it really helps lower stress and other symptoms because more and more people are interested in natural ways to deal with stress.

What is Ashwagandha?

The evergreen shrub ashwagandha grows in India and other parts of Asia and Africa. The root of the plant is the part that is used for medicine. It has active compounds called withanolides (a type of steroidal lactone) and alkaloids. It is thought that these phytochemicals are what give ashwagandha its biological effects. Most modern supplements use either concentrated root extracts or dried root powder. Standardized extracts (like KSM-66, Sensoril, Shoden, and Witholytin) are made to have certain amounts of withanolides. 

Some products contain leaf extract, but most studies focus on the root. In traditional use, whole root powder might be brewed as a tea or taken in large doses, but clinical studies usually use much smaller amounts of a concentrated extract.  One review of stress-and-anxiety trials, for instance, found that doses of extract ranged from about 240 to 1,250 mg per day. On the other hand, a whole-root preparation of 12,000 mg of granules was equal to about 6,000 mg of powdered root (rootods.od.nih.gov).

Adaptogens, such as ashwagandha, are vaguely defined as substances that assist the body in resisting stressors and preserving homeostasis. 

The word "adaptogen" isn't a strict medical term, but it fits with the idea that ashwagandha may help people deal with stress better. Ashwagandha has been used for a long time as a rejuvenating tonic and a mild sedative (the name somnifera means "sleep-inducing"). Scientists are interested in whether modern extracts can really help with stress and anxiety, help people sleep better, and change hormones that are related to these things.

How Stress Impacts the Body

Stress sets off a well-planned biological reaction. 

The hypothalamus tells the adrenal glands to release "stress hormones," which are adrenaline (epinephrine) and cortisol, when the brain senses a threat.  Adrenaline gets the body ready to deal with danger by making the heart race, breathing faster, and senses sharper. 

It's important to note that the common term "adrenal fatigue"—the idea that the adrenals wear out and stop making cortisol when they're under stress—isn't supported by medical research. In fact, doctors stress that when you're under stress, the adrenals usually make more cortisol, not less. In short, effective stress management means keeping the HPA axis and cortisol responses in check so that you get the energy boost from cortisol in emergencies but don't have to deal with the effects of chronic overproduction.

Studies on Ashwagandha and Stress

More and more clinical studies are looking into how ashwagandha affects mood, sleep, anxiety, and stress.  The evidence is good, but it's not easy to understand.  Most studies and reviews show that ashwagandha can lower stress markers and make stress-related symptoms better compared to a placebo.  The most important findings are:

Meta-analyses and reviews: Numerous systematic reviews and meta-analyses have synthesized the randomized trials.  A 2024 meta-analysis (9 trials, 558 patients) demonstrated that ashwagandha significantly reduced perceived stress and anxiety scores, as well as cortisol levels, in comparison to placebo (pubmed.ncbi.nlm.nih.gov).  The aggregated data indicated a substantial decline in Perceived Stress Scale scores (mean difference −4.72, 95% CI −8.45 to −0.99) and a significant decrease in serum cortisol levels with ashwagandha. 

Other reviews also say that adults who took 250–500 mg of ashwagandha extract every day for a few weeks had much lower morning cortisol levels and better measures of anxiety and stress.  In summary, these consolidated analyses indicate that ashwagandha formulations surpass placebo in diminishing both biological (cortisol) and psychological (stress/anxiety scales) markers of stress.

Clinical trials, stress, and anxiety:

In a 30-day U.S. study involving 60 stressed men and women, those administered 225 mg or 400 mg daily of a standardized ashwagandha extract exhibited markedly reduced scores in stress, anxiety, and depression compared to the placebo group.  The low-dose (225 mg) group also had lower levels of cortisol in their saliva, which is interesting.  In India, a 90-day trial involving 130 healthy adults utilizing a slow-release ashwagandha extract (one 300 mg capsule containing 15 mg withanolides per day) demonstrated significant enhancements: the ashwagandha group reported reduced perceived stress and improved sleep quality, alongside lower blood cortisol levels compared to the placebo group. 

Cortisol vs. perceived stress:

It's interesting, ashwagandha has a stronger effect on cortisol than on subjective stress scales. 

For instance, a meta-analysis conducted in 2025 revealed that ashwagandha supplementation resulted in a substantial decrease in cortisol levels, averaging a reduction of approximately 1.16 µg/dL across trials (pubmed.ncbi.nlm.nih.gov).  However, the analysis revealed no statistically significant alteration in Perceived Stress Scale scores (a standardized self-report instrument). 

In conclusion, the majority of existing research suggests that ashwagandha may reduce stress hormones and alleviate feelings of stress or anxiety.  A lot of the trials are only 4 to 12 weeks long and involve mostly healthy stressed adults. More research is needed on long-term use and different groups of people. 

But for the question, "What does the research say?" Current evidence is favorable, indicating that regular consumption of ashwagandha extract consistently enhances stress indicators and mood in comparison to no treatment.

Recommended Dosages and Forms

There are many different kinds of ashwagandha supplements.  Root extracts in capsules or tablets are the most common.  These are usually hydro-alcoholic extracts that have been standardized to have a certain amount of withanolides, usually between 2.5% and 5%.  Some products use a mix of root and leaf, while others only use root powder.  Some people also use root powder (dried and ground), but it's not as strong. 

For example, they mix it into tea or smoothies.  One trial gave people 12,000 mg of whole-root granules every day, which is about 6 grams of root powderods.od.nih.gov, to see if it had the same effect as much smaller doses of extract.

The doses that were tested in trials are very different from each other.  Most studies on stress use a concentrated extract that is between 250 and 600 mg per day.  A systematic review indicated that numerous trials administered 250–500 mg daily for 4–13 weeks, resulting in a significant reduction of cortisol levels in stressed adults (nutritionandmetabolism.biomedcentral.com).  Some studies use more; one review said that doses of extract ranged from 240 to 1,250 mg/day across trials.  A practitioner task force has tentatively suggested a dosage of 300–600 mg daily of a 5%-withanolide root extract for generalized anxiety, indicating this range.  In practice, most supplement labels say to take 300–500 mg once or twice a day.

In short, the literature suggests the following forms and doses:

Root extract capsules: The form that has been studied the most.  A standard extract nutrition and metabolism dose is usually between 250 and 600 mg per day, split into two doses.  Some brands, like KSM-66, Sensoril, Witholytin, and Shoden, offer extracts that are standardized to 2.5% to 10% withanolides.

Whole root powder: People have used it in larger amounts for a long time.  Plain powder is not often used in clinical settings; one trial used 12 g of ashwagandha granules (the same as 6 g of powder) per day.  In general, you might need several grams of powder to get the same effect as a 300 mg extract.

Liquid extracts or tinctures: These are not as studied as some other forms, but they also deliver concentrated levels of withanolides. The amount of liquid you take depends on how strong the product is, but it should be about the same as capsule extracts.

In general, most studies and expert advice suggest a daily dose of 300 to 600 mg of a standardized root extract. Some people may take slightly higher doses, up to 1,000–1,200 mg/day, depending on how well they tolerate the product and what the instructions say. According to the trial dataods.od.nih.gov, doses below 250 mg/day don't work as well. It's best to follow the directions on the supplement you buy or talk to a doctor for personalized advice.

Safety, Side Effects, and Who Should Not Use It

Most adults can safely use ashwagandha for a short time (up to a few months), but there are some things to keep in mind. Clinical trials indicate that ashwagandha is generally well tolerated, exhibiting only mild side effects in the majority of users. Some common mild symptoms are upset stomach (nausea, diarrhea, stomach pain), drowsiness, and headaches that happen from time to time. In placebo-controlled trials, these effects manifest at low frequencies and exhibit similarities between ashwagandha and control groups.

In rare cases, though, more serious effects have been seen. There are a few reports of people who took ashwagandha supplements and hurt their livers. For instance, people who took ashwagandha along with other anxiety medications reported having cholestatic hepatitis in a few cases. People who already have liver disease or are taking a lot of herbs or drugs should be careful because of this. Some studies have found small increases in thyroid hormone (T4) levels, and a few case reports describe hyperthyroid symptoms that went away when the herb was stopped. This suggests that ashwagandha may also affect thyroid function. So, people who take thyroid drugs should talk to their doctor before using ashwagandha. Ashwagandha can make the effects of blood pressure medications, sedatives, immunosuppressants, and diabetes drugs stronger or weaker. Other drugs that may interact with it are blood pressure medications, sedatives, immunosuppressants, and diabetes drugs.

People in some groups should not take ashwagandha.

Pregnant or breastfeeding women are one of the groups of people that are discouraged from taking ashwagandha because there's concerns (though not techincally proven) that it could affect pregnancy or hormone balance. Some regulatory agencies have even banned it for pregnant women as a precaution. Similarly, men with hormone-sensitive prostate cancer should not take it because ashwagandha can raise testosterone levels. People who are going to have surgery should stop taking ashwagandha at least two weeks before the surgery because it can make anesthesia work better. People with autoimmune diseases or thyroid problems should also be careful because the herb's effects on the immune system and thyroid could make these conditions worse.

Lastly, it's important to remember that long-term safety is not fully known. Most trials last only 4 to 12 weeks, and most do not report serious adverse events. So, while short-term use seems safe for most healthy adults, we don't know what years of taking supplements will do. To avoid contaminants, people should only buy from well-known brands and start with a low dose to see how their body reacts. 

Conclusion

Ashwagandha is an ancient Ayurvedic herb that has recently gained the attention of scientists for its ability to reduce stress. Researchers have done a lot of clinical studies in the last few decades to find out how it affects stress, anxiety, sleep, and mood. Studies also show that it can help you sleep better and feel less tired, which can make you feel better overall.

Standardized root extracts (usually 2–5% withanolides) are commonly used in research at doses of several hundred milligrams per day. Most adults seem to be able to use it safely for a short time, with only mild side effects reported in trials. However, some people, like pregnant or breastfeeding women and people with certain health problems, should stay away from it or talk to a doctor first.

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