Ashwagandha is one of those supplements that has gained enormous popularity in recent years, yet I find that most people who take it have only a vague sense of what it actually does. The marketing tends to throw around words like “adaptogen” and “stress relief” without much explanation.

I should note upfront that ashwagandha is one of the better-studied herbal supplements, with genuine randomised controlled trials behind many of its claimed benefits. That said, the evidence varies considerably depending on which effect you are interested in.

In this article, I review what the research actually shows for seven commonly claimed benefits of ashwagandha, discuss the side effects, and outline ten safety precautions that anyone considering this supplement should know about.

What is Ashwagandha?

Ashwagandha (Withania somnifera) is a plant that has been used in Indian Ayurvedic medicine for around three thousand years. The name comes from Sanskrit and translates roughly as “smell of horse” - probably a reference to the distinctive odour of the root. The Latin species name somnifera means “sleep-inducing,” which gives you a hint about one of its traditional uses.

In Ayurvedic practice, ashwagandha is classified as a “rasayana,” which essentially means a rejuvenating tonic. The modern term you will hear most often is “adaptogen” - herbs that supposedly help the body adapt to physical or mental stress. Other plants in this category include ginseng, maca, and rhodiola.

The root and leaves contain several classes of active compounds, most notably withanolides (which are steroidal lactones), along with alkaloids, saponins, and various amino acids. Laboratory studies suggest these compounds may have anti-inflammatory, antioxidant, and immune-modulating properties, though I should emphasise that test tube findings do not always translate to effects in humans. 1

7 Evidence-Based Benefits of Ashwagandha

1. Ashwagandha May Help Reduce Stress

This is probably the most popular use of ashwagandha, and it is also one of the better-supported claims.

A 2022 systematic review and meta-analysis pooled data from 12 randomised controlled trials involving 1,002 participants. The analysis found that ashwagandha supplements significantly reduced anxiety and stress levels compared to placebo. 2

My interpretation: The evidence here is reasonably consistent, though I would note that many of the individual trials were small and short-term. The effect sizes were modest rather than dramatic. If you are dealing with chronic stress, ashwagandha might help take the edge off, but it is not going to replace lifestyle changes or professional support for more serious stress-related conditions.

2. Ashwagandha May Improve Sleep Quality

Poor sleep affects a large proportion of the adult population, and I notice many people turn to supplements like ashwagandha as an alternative to prescription sleep aids.

A 2021 systematic review examined five randomised controlled trials with 400 participants. The researchers found that ashwagandha extract had a clinically beneficial effect on several sleep measures: overall sleep quality, time to fall asleep (sleep latency), total sleep duration, time awake after initially falling asleep, and sleep efficiency. 3

The subgroup analysis was interesting - the improvements were more pronounced in people who had been formally diagnosed with insomnia (as opposed to those who simply reported sleeping poorly), in those taking doses of 600 mg or more daily, and when treatment lasted at least eight weeks.

My interpretation: This is encouraging evidence, particularly for people with actual insomnia. I should point out that the trials were relatively small, so we cannot be entirely certain about long-term effects or optimal dosing. For occasional poor sleep, the benefits may be less noticeable.

3. Ashwagandha May Benefit Male Fertility

Male factor infertility contributes to roughly half of all cases where couples struggle to conceive. Most commonly, the issue involves low sperm concentration or poor sperm motility.

A 2018 systematic review and meta-analysis looked at four observational studies and one randomised controlled trial examining ashwagandha’s effects on male fertility. The analysis found significant improvements in sperm concentration, semen volume, and sperm motility. There were also favourable changes in hormonal profiles and markers of oxidative stress in seminal fluid. 4

My interpretation: The results are encouraging, but I have to be honest about the limitations here. Most of the evidence comes from observational studies rather than rigorous trials, and the total number of participants was small. If you are dealing with fertility issues, ashwagandha might be worth discussing with your doctor as part of a broader approach, but I would not rely on it as a primary treatment.

For more on this topic, you might find our article on health foods that may benefit male fertility useful.

4. Ashwagandha May Enhance Physical Performance

Athletes and fitness enthusiasts often look to supplements for an edge, and ashwagandha has attracted attention in this area.

A 2021 systematic review and meta-analysis examined 12 studies involving 615 healthy adults. The researchers found that ashwagandha supplementation improved measures of strength and power, cardiorespiratory fitness, and fatigue recovery compared to placebo. 5

My interpretation: The improvements were real but relatively modest. I would not expect ashwagandha to transform your athletic performance, but it might provide a small additional benefit on top of proper training and nutrition. The quality of individual studies varied, and more research would help clarify the optimal dosing and duration.

5. Ashwagandha May Help with OCD Symptoms

Obsessive-compulsive disorder affects roughly 1-3% of the population and can significantly impair quality of life. Standard treatments include SSRIs (selective serotonin reuptake inhibitors) and cognitive behavioural therapy, but not everyone responds fully to these approaches.

A double-blind controlled study followed 30 patients with OCD who were already receiving SSRI treatment. Those who added ashwagandha to their regimen showed greater improvement on the Yale-Brown Obsessive-Compulsive Scale compared to those on medication alone after six weeks. 6

The proposed mechanism involves ashwagandha’s effects on serotonin synthesis and synaptic transmission. 7

My interpretation: This is a single small study, so I would be cautious about drawing strong conclusions. However, for people with OCD who have not achieved full relief from standard treatments, it might be reasonable to discuss ashwagandha with their psychiatrist as a potential adjunct therapy. I would not recommend using it as a substitute for proven treatments.

For related information, see our article on adjuvant therapies for obsessive-compulsive disorder.

6. Ashwagandha May Improve Female Sexual Function

Sexual dysfunction in women is common and often underdiagnosed. Symptoms can include low libido, difficulty with arousal, vaginal dryness, and problems achieving orgasm. These issues frequently have both psychological and physiological components.

A preliminary double-blind study followed 50 healthy women with sexual dysfunction over eight weeks. Those taking ashwagandha showed improvements on several measures: orgasm, satisfaction, vaginal moistness, sexual arousal, and the number of successful sexual encounters. 8

The researchers suggested the effect might work through stress reduction and through a modest increase in testosterone (since androgen deficiency can contribute to sexual dysfunction in women).

My interpretation: This was a small preliminary study, so the findings need replication before we can be confident. The results are promising enough that larger trials would be worthwhile. For women experiencing sexual dysfunction, I would suggest addressing any underlying medical or relationship issues first, but ashwagandha might be a reasonable option to discuss with a healthcare provider.

7. Ashwagandha May Reduce Anxiety

While I discussed stress relief earlier, anxiety disorders are a distinct clinical category that warrants separate consideration. These include generalised anxiety disorder, social anxiety, panic disorder, and others.

A systematic review examined five randomised controlled trials of ashwagandha for anxiety. The pooled results showed significant improvements in anxiety and stress scale scores compared to various control groups, including placebo and psychotherapy. 9

Animal studies have found that ashwagandha produces anti-anxiety effects similar to certain pharmaceutical medications. 10

My interpretation: The evidence suggests ashwagandha can help with mild to moderate anxiety symptoms. However, I would not recommend it as a substitute for professional treatment of clinically diagnosed anxiety disorders. It might work well as part of a comprehensive approach that includes therapy, lifestyle modifications, and possibly medication depending on severity.

What Are the Side Effects of Ashwagandha?

According to a 2021 systematic safety review, ashwagandha is generally considered safe and well tolerated at small to medium doses for short-term use. 11 Most clinical trials have not reported serious adverse events.

However, the safety of long-term use (beyond several months) has not been well established. Some people do experience side effects, particularly at higher doses:

Gastrointestinal symptoms: Indigestion, nausea, diarrhoea, and stomach discomfort are the most commonly reported issues
Sedation: Given its traditional use as a sleep aid, some people may experience drowsiness, particularly when starting or increasing the dose

The NHS and Mayo Clinic both note that while ashwagandha appears generally safe for short-term use, more research is needed on long-term safety profiles. 12

10 Safety Precautions

There are several groups of people who should either avoid ashwagandha or use it only under medical supervision:

Pregnant and breastfeeding women should not take ashwagandha. There are concerns it may cause miscarriage, and we simply do not have adequate safety data for these populations.
Children should not use ashwagandha, as safety in paediatric populations has not been established.
People with liver or kidney disease should be cautious, as there have been case reports of liver injury associated with ashwagandha use. 13 Symptoms appeared between 2 and 12 weeks after starting the supplement and included nausea, abdominal discomfort, jaundice, itching, and fatigue.
Those taking blood pressure or blood sugar medications should be aware that ashwagandha may lower both blood pressure and blood glucose, potentially enhancing drug effects. For people managing conditions like diabetic bladder dysfunction, this interaction is worth discussing with your doctor.
People with autoimmune conditions should generally avoid ashwagandha. It may stimulate the immune system, which could worsen conditions such as rheumatoid arthritis, lupus, Hashimoto’s thyroiditis, or type 1 diabetes.
Those with thyroid disorders need to exercise caution. Ashwagandha may increase thyroid hormone levels, and there have been documented cases of thyrotoxicosis (excessive thyroid hormone) following supplementation. 14 Symptoms can range from palpitations and weight loss to more serious complications like arrhythmias.
People with peptic ulcers should avoid ashwagandha, as it may irritate the gastrointestinal lining.
Anyone scheduled for surgery should stop ashwagandha at least two weeks beforehand. It may slow central nervous system activity and interfere with anaesthesia.
Those taking sedatives, sleep medications, or immunosuppressants should not combine these with ashwagandha due to potential drug interactions.
Organ transplant recipients should avoid ashwagandha entirely. There is a documented case of acute kidney transplant rejection in a patient who was taking ashwagandha. 15

Additionally, there have been reports of fixed drug eruption (a type of skin reaction) associated with ashwagandha supplementation. 16

Recommended Dosage

Most clinical trials have used doses ranging from 300 mg to 600 mg of root extract daily, typically standardised to a certain percentage of withanolides. Some studies have used higher doses up to 1,000 mg daily.

For sleep benefits, the evidence suggests that doses of 600 mg or more may be more effective, and that effects become more noticeable after at least eight weeks of consistent use.

I would generally recommend starting at a lower dose and increasing gradually while monitoring for any adverse effects.

The Bottom Line

Ashwagandha is one of the more evidence-backed herbal supplements available, with particular support for its effects on stress, sleep, and anxiety. The research on male fertility and physical performance is encouraging but more preliminary.

That said, ashwagandha is not without risks. The list of contraindications is substantial, and there are documented cases of serious adverse effects including liver injury and thyroid problems. If you fall into any of the risk categories I outlined above, I would strongly advise consulting with a healthcare provider before trying this supplement.

For generally healthy adults looking to manage everyday stress or improve sleep, ashwagandha appears to be a reasonably safe option for short-term use. Just do not expect dramatic transformations - the effects in clinical trials were statistically significant but modest.

References

Singh N, et al. An overview on ashwagandha: a Rasayana (rejuvenator) of Ayurveda. Afr J Tradit Complement Altern Med. 2011;8(5 Suppl):208-213. PubMed
Akhgarjand C, et al. Does Ashwagandha supplementation have a beneficial effect on the management of anxiety and stress? A systematic review and meta-analysis of randomized controlled trials. Phytother Res. 2022;36(11):4115-4124. PubMed
Cheah KL, et al. Effect of Ashwagandha (Withania somnifera) extract on sleep: A systematic review and meta-analysis. PLoS One. 2021;16(9):e0257843. PubMed
Durg S, et al. Withania somnifera (Indian ginseng) in male infertility: An evidence-based systematic review and meta-analysis. Phytomedicine. 2018;50:247-256. PubMed
Bonilla DA, et al. Effects of Ashwagandha (Withania somnifera) on Physical Performance: Systematic Review and Bayesian Meta-Analysis. J Funct Morphol Kinesiol. 2021;6(1):20. PubMed
Jahanbakhsh SP, et al. Evaluation of the efficacy of Withania somnifera (Ashwagandha) root extract in patients with obsessive-compulsive disorder: A randomized double-blind placebo-controlled trial. Complement Ther Med. 2016;27:25-29. PubMed
Schliebs R, et al. Systemic administration of defined extracts from Withania somnifera (Indian Ginseng) and Shilajit differentially affects cholinergic but not glutamatergic and GABAergic markers in rat brain. Neurochem Int. 1997;30(2):181-190. PubMed
Dongre S, et al. Efficacy and Safety of Ashwagandha (Withania somnifera) Root Extract in Improving Sexual Function in Women: A Pilot Study. Biomed Res Int. 2015;2015:284154. PubMed
Pratte MA, et al. An alternative treatment for anxiety: a systematic review of human trial results reported for the Ayurvedic herb ashwagandha (Withania somnifera). J Altern Complement Med. 2014;20(12):901-908. PubMed
Bhattacharya SK, et al. Anxiolytic-antidepressant activity of Withania somnifera glycowithanolides: an experimental study. Phytomedicine. 2000;7(6):463-469. PubMed
Tandon N, Yadav SS. Safety and clinical effectiveness of Withania Somnifera (Linn.) Dunal root in human ailments. J Ethnopharmacol. 2020;255:112768. PubMed
Mayo Clinic. Ashwagandha. Mayo Clinic
Björnsson HK, et al. Ashwagandha-induced liver injury: A case series from Iceland and the US Drug-Induced Liver Injury Network. Liver Int. 2020;40(4):825-829. PubMed
Kamal HI, et al. Ashwagandha as a unique cause of thyrotoxicosis presenting with supraventricular tachycardia. Cureus. 2022;14(3):e23494. PubMed
Patel DP, et al. Ashwagandha-associated acute kidney allograft rejection. Transplantation. 2020;104(10):e291-e292. PubMed
van der Hooft CS, et al. Ashwagandha (Withania somnifera)-induced fixed drug eruption. Drug Saf. 2012;35(2):159. PubMed