By Dr. Maya Reynolds
Integrative Medicine Physician
Dr. Maya Reynolds is an integrative medicine physician and medical writer specializing in evidence-based health, nutrition, and supplement education. She helps readers understand what scientific research says about commonly used supplements while explaining potential side effects, interactions, and situations where professional medical advice is appropriate. Her goal is to make health information practical, balanced, and easy to understand.
You may notice ashwagandha supplements put out with protein powders, magnesium and other health products and question what they do. Also you may be to try it out because stress has been a issue, your sleep has been off, or you may have heard that it could improve how you perform at the gym. What they report is that the evidence is more complex than what you see in most supplement ads. Ashwagandha is best known for studies on stress and sleep, also the results by and large break in which preparation and study design.
Ashwagandha also known by the name Withania somnifera is a plant that has been used in Ayurvedic medicine. Present day research has looked at the root and leaf extracts for many uses but what they used in each study varied which in turn has varied also the doses. This in turn makes it hard to apply the results of one study to products which all label themselves as ashwagandha. NCCIH
What Is Ashwagandha?
Ashwagandha is a woody shrub that grows in some regions of India, Africa, and the Middle East. It goes by the scientific name of Withania somnifera which also is used for the supplements that may include root, leaf, or a combination of both. In the plant we find a group of natural compounds named with anolides. NCCIH.
The plant is a player in traditional remedies for what may be a very long time, that said traditional use does not equate to modern clinical evidence. A supplement may have a very long history of use yet still require controlled human research to determine its efficacy for a certain health issue.
Ashwagandha products are put forth for use in anything from stress and sleep to athletic performance, testosterone, cognition and general health. NCCIH reports we have better evidence for some stress and insomnia benefits than we do for many of these other claims. NCCIH
What Are the Potential Ashwagandha Benefits?
The evidence is strongest when the question is narrow. Rather than asking whether ashwagandha is simply “good for you,” it is more useful to ask what researchers have actually tested.
Stress and Perceived Stress
Stress is one of the areas where human research has produced promising results.
The NIH Office of Dietary Supplements reports that in some clinical studies we see reduction in reported stress, anxiety scores, sleep issues, fatigue, and cortisol in comparison to placebo. Study results did vary greatly however. In the studies we looked at doses ranged between 240 to 1,250 mg per day of extract in which case the material was very concentrated and also much larger amounts which used the whole root in granule form which did not be equal to the same concentration as the extract. Office of Dietary Supplements
In 2022 a systematic review and meta-analysis of that which looked at 12 randomized trials which included 1,000 and which reported stress and anxiety reduction as compared to placebo. But what is put forth is that the evidence is of low quality by the authors’ report which in turn means that the results should be looked at carefully and not presented as fact. PubMed
A newer systematic review published in 2024 included nine randomized controlled trials involving 558 participants and also reported improvements in stress measures, anxiety scores, and cortisol. Again, the authors noted the need for more research on long-term safety. PubMed
So the practical interpretation is fairly simple: ashwagandha may help some people with perceived stress, but the evidence does not justify treating it as a proven treatment for an anxiety disorder or chronic stress-related illness.
Does Ashwagandha Really Work for Anxiety and Stress?
It may help with perceived stress, but evidence for anxiety is less certain than supplement marketing often suggests.
This distinction is important.
The 2022 meta-analysis found statistically significant improvements in anxiety and stress, but also reported high variability between studies and low certainty of evidence. PubMed
NCCIH takes a more cautious position: it says some ashwagandha preparations may be effective for stress, while evidence about anxiety remains unclear. NCCIH
That does not mean the supplement has no potential value. It means that a person should not replace professional evaluation for significant anxiety with an over-the-counter supplement based on advertising claims.
If anxiety is persistent, interferes with daily life, causes panic symptoms, or is accompanied by thoughts of self-harm, appropriate medical or mental-health care is more important than experimenting with supplements.
Ashwagandha and Sleep
Sleep is another area with some encouraging evidence.
A systematic review and meta-analysis published in PLOS ONE analyzed five randomized controlled trials involving 400 participants. The researchers found a small but statistically significant improvement in overall sleep, with stronger effects in studies involving people with insomnia, doses of at least 600 mg per day, and treatment lasting at least 8 weeks. PubMed
That does not mean everyone needs 600 mg per day.
The studies used different products, and supplement labels are not standardized around one universal extract. A dose that appears in a clinical trial cannot automatically be transferred to every product on a store shelf.
For someone whose main problem is persistent insomnia, it is also worth investigating underlying causes rather than relying entirely on a supplement.
What About Ashwagandha for Exercise and Athletic Performance?
Ashwagandha is widely marketed to athletes and gym-goers, but the evidence is not as established as the advertising may imply.
NCCIH currently says there is not enough evidence to determine whether ashwagandha is helpful for athletic performance. NCCIH
That is a useful distinction for people comparing ashwagandha with more established sports-nutrition strategies.
If your goal is improving training performance, basics such as an appropriate exercise program, sufficient protein and calories, sleep, and recovery should not be displaced by a supplement whose evidence remains uncertain.
Ashwagandha and Testosterone
There is some evidence suggesting that certain ashwagandha preparations may affect testosterone and sperm quality, but the evidence is limited.
NCCIH reports limited evidence that taking ashwagandha for 2 to 4 months may increase testosterone levels and sperm quality. It also notes that evidence is insufficient for several other reproductive and hormonal claims. NCCIH
This is not the same as saying ashwagandha is a proven testosterone booster.
Hormone-related supplements deserve extra caution because changing hormone levels can be helpful in one context and inappropriate in another.
NCCIH specifically advises against ashwagandha for men with hormone-sensitive prostate cancer because of its potential effects on testosterone. NCCIH
How Much Ashwagandha Should You Take?
There is no single standard dose that applies to every ashwagandha supplement.
This is one of the most important points to understand before buying a product.
Clinical studies have used different:
- Extracts
- Plant parts
- Concentrations
- Standardization methods
- Daily doses
- Treatment periods
NIH’s Office of Dietary Supplements reports that studies have used approximately 240–1,250 mg/day of extracts, while some whole-root preparations have used substantially larger amounts. Several studies reporting benefits used around 500–600 mg/day, but that does not establish a universal recommended dose for all products. Office of Dietary Supplements
Why the number on the bottle can be misleading
Imagine two products:
Product A: 300 mg of a concentrated extract
Product B: 600 mg of a less concentrated preparation
The larger number on Product B does not automatically mean it is twice as strong.
The plant material, extraction method, and concentration of active constituents all matter.
What Is the Best Time to Take Ashwagandha?
There is no universally established “best” time of day.
If a particular product makes you feel drowsy or relaxed, taking it later in the day may be more convenient. If it causes stomach upset, taking it with food may be easier for some people.
However, the most important issue is following the product label and any instructions provided by your healthcare professional rather than choosing a schedule based on social-media advice.
There is also no good reason to assume that taking a larger dose at night will necessarily produce better sleep.
Ashwagandha Side Effects: What Should I Actually Expect?
The primary side effects reported are mild digestive issues and drowsiness but also in rare cases of liver injury we have reported.
NIH reports of side effects:
• Stomach upset
• Loose stools
• Nausea
• Vomiting
• Drowsiness
These in most of the short term clinical studies NCCIH reported mostly mild results.
But “natural” does not mean “risk-free.”
The issue of safety plays out in different terms when we look at long term use, interactions, and health conditions.
Can Ashwagandha Cause Liver Problems?
Rare cases of liver injury have been associated with ashwagandha-containing supplements.
This is one of the warnings that should not be buried in fine print.
The NIH’s LiverTox database describes reported cases in which liver injury developed after people started products labeled as containing ashwagandha. In many cases, symptoms appeared 2 to 12 weeks after starting the supplement, often involving jaundice and itching. Most reported cases improved after discontinuation, but serious and even fatal cases have been described, particularly among people with pre-existing liver disease. NCBI
A peer-reviewed case series also documented five cases attributed to ashwagandha-containing supplements after other causes of liver injury were excluded. PubMed
A 2026 scoping review identified 25 patients across 13 publications describing ashwagandha-associated liver injury through the end of 2025. The authors reported that injury typically developed after weeks of use, with cholestatic or mixed patterns common among reported cases. PubMed
Warning signs to take seriously
If reports of side effects from someone who is on ashwagandha:.
• Jaundice of the skin or eyes.
• Dark urine
• Unusual itching
• Significant nausea
• Abdominal discomfort
• Unusual fatigue
They should break the habit of thinking of this as a safe health product and get a medical assessment right away.
People who have liver disease should talk to a health care provider before trying ashwagandha.
Can Ashwagandha Affect the Thyroid?
Yes, there is evidence that ashwagandha may influence thyroid hormone levels.
NIH’s Office of Dietary Supplements describes studies in which ashwagandha affected thyroid hormone measurements. It also notes several case reports of thyrotoxicosis in people taking ashwagandha, with symptoms resolving after discontinuation. Office of Dietary Supplements
This is especially relevant if you:
- Have a thyroid disorder
- Take thyroid hormone medication
- Have symptoms suggesting excess thyroid hormone
NCCIH recommends avoiding ashwagandha in people with thyroid disorders and warns about a possible interaction with thyroid hormone medications. NCCIH
That makes “I have a thyroid problem, but it’s just an herbal supplement” an unsafe assumption.
Who Should Avoid Ashwagandha?
NCCIH specifically advises against ashwagandha during pregnancy and breastfeeding. It also says it is not recommended for people who are about to undergo surgery or those with autoimmune or thyroid disorders. NCCIH
Extra caution is appropriate if you:
- Take several prescription medications
- Have liver disease
- Have a thyroid condition
- Have an autoimmune condition
- Are pregnant or breastfeeding
- Have hormone-sensitive prostate cancer
- Are preparing for surgery
The appropriate decision may be avoiding the supplement altogether or discussing it with your healthcare professional first.
Can Ashwagandha Interact With Medications?
Yes. NCCIH reports on issues of interaction for:
• Diabetes
• High blood pressure
• Suppressing immune activity
• Sedation
• Seizure control
• Thyroid hormone replacement. NCCIH
This does not mean that all people on these drugs will have an interaction. What it does mean is that the combination should be reviewed by a professional.
If you are taking any prescription medications bring to your doctor or pharmacist the complete supplement label which includes all ingredients and doses. Different preparations may have varying ingredients and strengths.
Can Ashwagandha Make You Depressed or Anxious?
There is not good evidence that ashwagandha routinely causes depression or anxiety, but that does not mean every mood change should be ignored.
Most clinical research discussed by NIH has investigated whether ashwagandha might reduce perceived stress or anxiety scores rather than showing that it causes these conditions. Some trials have even reported improvements in mood-related measures. Office of Dietary Supplements
However, if you notice new or worsening:
- Anxiety
- Low mood
- Irritability
- Agitation
- Sleep disruption
- Unusual changes in behavior
after starting a supplement, do not assume you need to “push through” the symptoms.
Stop and discuss the change with a healthcare professional, particularly if symptoms are severe or you take other medications or supplements.
How Long Is It Safe to Take Ashwagandha?
This is where the evidence has a major limitation.
Short-term studies suggest that some preparations are generally well tolerated for up to about three months, but there is not enough evidence to establish the safety of long-term daily use over many months or years.
NCCIH explicitly states that ashwagandha may be safe in the short term, up to about three months, but there is insufficient information about long-term safety. NCCIH
That means you should be cautious about advice suggesting that everyone should take ashwagandha indefinitely.
More is not automatically better, and longer is not automatically safer.
How to Choose an Ashwagandha Supplement
If you decide, with appropriate guidance, that ashwagandha is worth considering, product quality matters.
Dietary supplements are regulated differently from prescription medicines in the United States. The FDA does not approve dietary supplements for safety and effectiveness before they reach the market. Manufacturers are responsible for meeting applicable safety and labeling requirements, while FDA oversight is primarily post-market. U.S. Food and Drug Administration
Look for a label that clearly identifies:
- The plant name
- Which plant part is used
- Amount per serving
- Extract information when provided
- Other active ingredients
- Manufacturer information
- Lot or batch information
Be cautious with products that make dramatic promises such as “cures anxiety,” “reverses aging,” or “guarantees hormone optimization.”
A supplement marketed as a cure for a disease should raise questions because supplements are not approved by FDA to diagnose, treat, cure, or prevent disease. U.S. Food and Drug Administration
Common Ashwagandha Mistakes to Avoid
Finding the highest dose available
Clinical research does not support that which is the highest dose is the best.
Better approach: Compare your preparation to what is reported in the research and discuss it with health care provider when appropriate.
Assuming All Extracts Are Equivalent
A 300 mg extract is not always equivalent to 300 mg of raw root.
Better approach: Read the Supplement Facts section.
Ignoring Existing Medical Conditions
A simple supplement may in fact be an issue if it affects thyroid health, liver function, blood pressure, blood sugar, or immune activity.
Better approach: Review your medications and health history.
Taking It Indefinitely Without Reassessment
Most studies do not report on long term safety.
Better approach: If for a set goal you use it do a review of what it is doing for you before you make it a permanent part of your routine.
Ashwagandha vs Other Popular Supplements
Ashwagandha often appears in the same wellness conversations as magnesium glycinate vs citrate, collagen supplements, creatine, and vitamin D.
But these are not interchangeable.
Creatine, for example, has a very different evidence base and primary use case than ashwagandha. Likewise, vitamin D supplementation should generally be guided by dietary intake, risk factors, and appropriate testing rather than treating every symptom as a deficiency.
This is why supplement decisions should begin with the question:
“What specific problem am I trying to address?”
Then evaluate the evidence and risks for that particular goal.
Frequently Asked Questions
What does Ashwagandha do?
At present best support is for some stress and sleep measures. As for anxiety, testosterone, sperm quality, and exercise performance some studies have reported on these but the evidence is mixed or not well worked out for many of them. NCCIH reports that for anxiety there is in fact not enough evidence and that for many other conditions the evidence is still very much up in the air.
What is the dose of ashwagandha I should take daily?
There is no set dose for any product. We have reported on a range of what human studies have used which included 240 to 1,250 mg per day of extracts. Some stress studies reported on doses between 500 to 600 mg per day but we do not put forth these as a standard dose recommendation.
How soon do you see results from ashwagandha?
Studies report out results at various time points. Some research reports on the effects of treatment after few weeks and also we see that in sleep studies there is a better report of strong effects at 8 weeks mark or more. This does not mean that the same timeline will apply to each individual.
Is it ok to take ashwagandha daily?
Short in the term we see that most respond well to treatment for a period of about 3 months’ duration but what we don’t have is long term data. Also we see that rare reports of liver injury and thyroid issues are there which means that indefinite use cannot be taken to be safe.
Can women take ashwagandha?
Some reports include women in their study groups but we must note that pregnancy and breast feeding are issues which are out of the question. NCCIH recommends staying away from ashwagandha during pregnancy and whiling breast feeding. Also if you are pregnant, thinking of getting pregnant, or breast feeding we advise you to talk to your health care professional about supplements.
Can ashwagandha help with sleep?
Possibly. In 2021 a study of 5 RCTs and 400 adult participants found that that there was a small improvement in sleep overall, in some studies which used at least 600 mg/day and 8 week or longer treatment we saw larger results.
Does ashwagandha reduce cortisol?
Some studies report on reduced cortisol levels and meta analyses have noted that cortisol does change in relation to the placebo. But cortisol is one bio marker and should not present as the sole determine of health or supplement efficacy.
Final Thoughts
The issue with how we think of ashwagandha benefits is that they don’t play out in black and white. We see that some preparations do in fact help with stress and sleep according to research, while at the same time we can’t say the same for many of the other common claims. Also what works best for dose is not what the largest number on the supplement label says we find that studies use different extracts and preparations. NCCIH.
Safety is a concern. We see mild digestive issues and drowsiness which may present, also in very rare cases we see liver injury and that the product may affect the thyroid which is a reason against long term use of it. Also in the case of pregnancy, breastfeeding, thyroid or auto immune disorders, liver disease, pre-operative period, and use of other medications it is best to seek out professional advice before use. NCCIH