Table of Contents
- Current view (reviewed 23 October 2026)
- Key safety points
- Brad's videos on this topic
- Overview
- Forms and Bioavailability
- Evidence for Benefits
- Recommended Dosing
- Safety and Side Effects
- Drug Interactions
- Dietary Sources
- References
Current view (reviewed 23 October 2026)
There is some human evidence that ashwagandha can improve anxiety, but the effect is inconsistent and the trials are small, so Brad does not think the evidence yet justifies adding another pill (Brad's current guidance, 31 Jul 2026). For exercise, a 2025 trial in 41 healthy non-athlete men found that 600 mg a day of root extract added nothing to the gains in aerobic capacity and blood measures from 8 weeks of HIIT, and Brad said more high-quality research is needed before drawing confident conclusions (Brad, 15 Oct 2025). In 2025 he said it may still help stress and anxiety, pointing to a 2009 trial in which naturopathic care that included 300 mg of ashwagandha twice daily cut anxiety scores by 56.5%, against 30.5% with psychotherapy, and to a 2024 meta-analysis of 9 trials in 558 people that found lower stress, anxiety and cortisol (Brad, 15 Oct 2025). When patients want to try it, he explains the evidence and its limits and suggests a product tested by consumerlab.com (Brad, 15 Oct 2025).
Key safety points
- Ashwagandha might interact with sedatives, thyroid hormone, immunosuppressants, and diabetes and blood pressure medicines; a case report links it to kidney transplant rejection [42, 99]. If you take prescription medicines, check with your doctor or pharmacist before starting.
- Rare but serious liver injury has been reported, including acute liver failure [81, 85, 107]. In one case series, all 3 deaths were in people with existing liver disease, and the authors warn of high mortality in this group, so people with liver disease may be safest avoiding it unless their doctor advises otherwise [85]. If your skin or eyes turn yellow, or you develop itching or nausea, stop taking it and see a doctor promptly [42, 81].
- Some experts advise against it in pregnancy and breastfeeding, and it might not be safe for men with hormone-sensitive prostate cancer [42, 91].
- It may raise thyroid hormone levels, and thyrotoxicosis has been reported; people with a thyroid condition or on thyroid medicine should ask their doctor first [42, 87].
- Its safety beyond about 3 months of use is not known [42].
- Common side effects are mild: stomach upset, loose stools, nausea and drowsiness [42, 79].
Brad's videos on this topic
- 15 Oct 2025, Ashwagandha Supplement Fails in New Study!: a new trial found no added benefit for aerobic capacity from 600 mg a day; earlier small trials and meta-analyses suggested gains but the evidence was weak; ashwagandha may still help stress and anxiety; Brad does not take it and prefers creatine for performance. Superseded in part on anxiety: Brad's 2026 guidance calls the anxiety effect inconsistent and the trials small.
1. Overview
Withania somnifera, known as ashwagandha, is an evergreen shrub grown in tropical and subtropical parts of Asia, Africa, and Europe [42]. Its root has been used in the Ayurvedic and Unani medicine systems of India as an adaptogen, loosely defined as a product that helps a person resist or adapt to biological, physical, or chemical stressors [2, 3, 42]. It is also called Indian ginseng or winter cherry, although it is not related to ginseng [42]. It belongs to the nightshade family (Solanaceae) [1].
The plant contains steroidal lactones called withanolides, along with alkaloids [42]. Withanolides are thought to drive many of its effects, though other, still unidentified compounds may also contribute [14, 42].
Root and leaf differ in their chemistry [42]. Laboratory work suggests that withanone, a major withanolide, can bind DNA and damage it when glutathione levels are low, which may help explain the liver injury cases [10]. Most commercial supplements contain root extract, though some include leaf [42].
Several small, short randomized trials suggest ashwagandha may reduce perceived stress and anxiety and improve sleep, but they used many different preparations and doses, which makes it hard to name a best extract or amount [42].
The World Federation of Societies of Biological Psychiatry (WFSBP) and the Canadian Network for Mood and Anxiety Treatments (CANMAT) provisionally recommend ashwagandha root extract for generalized anxiety disorder, though they note more data are needed for a stronger recommendation [16]. The taskforce's provisional dose for generalized anxiety disorder is 300-600 mg/day of a root extract containing 5% withanolides [42].
2. Forms and Bioavailability
Branded Extracts
Trials have used several branded extracts that differ in plant part and standardization.
| Extract | Plant Part | Standardization | Daily Doses Used in Trials |
|---|---|---|---|
| KSM-66 | Root only | More than 5% withanolides [42] | 300 mg twice daily [42] |
| Sensoril | Root + leaf (aqueous extract) [66] | Standardized aqueous extract [66] | 500 mg/day [66] |
| Shoden | Root + leaf [32] | 35% withanolide glycosides [32] | 60-240 mg/day [31, 32] |
| NooGandha | Root + leaf [23] | Proprietary extract [23] | 225-400 mg/day [23] |
| Witholytin | Root [42] | 1.5% withanolides [42] | 200 mg twice daily [42] |
Key Differences
Extracts that include leaf differ chemically from root-only extracts [42]. In a 2026 analysis of 25 supplements, only 2 were confirmed as root-derived; the rest contained varying, sometimes undisclosed, proportions of aerial parts [25]. Leaf-heavy samples carried compounds that distorted standard withanolide tests [25].
Withanolide Content and Quality
The same 2026 analysis found that 60% of the 25 products failed United States Pharmacopeia (USP) standards and over 44% failed British Pharmacopoeia standards; only 10 met both [25].
3. Evidence for Benefits
Anxiety
Meta-analyses of small trials have found lower anxiety and stress scores with ashwagandha than with placebo, though one rated the certainty of the evidence as low [28].
Meta-analyses:
A 2024 meta-analysis of 9 RCTs (n=558) found significant reductions in the Perceived Stress Scale (MD = -4.72, 95% CI -8.45 to -0.99), Hamilton Anxiety Scale (MD = -2.19, 95% CI -3.83 to -0.55), and serum cortisol levels (MD = -2.58, 95% CI -4.99 to -0.16) compared to placebo [27].
A 2022 meta-analysis of 12 RCTs (n=1,002) reported significant reductions in anxiety (SMD -1.55, 95% CI -2.37 to -0.74) and stress (SMD -1.75, 95% CI -2.29 to -1.22), with favorable dose-response effects particularly at 300-600 mg/day for stress; the certainty of the evidence was low for both outcomes [28].
A 2021 systematic review identified 7 studies of ashwagandha for stress and anxiety [9, 42].
Individual trials:
Employees with moderate or severe anxiety received naturopathic care (n = 41) or psychotherapy with placebo (n = 40) over a period of 12 weeks [30]. Naturopathic care combined diet counselling, deep breathing, a multivitamin and ashwagandha root extract, 300 mg twice daily (1.5% withanolides), and it lowered Beck Anxiety Inventory scores by 56.5%, against 30.5% with psychotherapy [30]. Because ashwagandha was one part of a package, the trial cannot show its effect alone [30].
In 60 adults with self-reported high stress, 240 mg of Shoden extract once daily for 60 days lowered Hamilton Anxiety Rating Scale scores (P = .040) and morning cortisol more than placebo [31].
In 60 adults with generalized anxiety disorder and high morning cortisol, Shoden (35% withanolide glycosides) at 60 or 120 mg a day for 60 days lowered Hamilton anxiety scores by 59%, against a 0.83% rise with placebo; morning cortisol fell by 66% and 67% in the two dose groups [32].
In a study of 130 healthy adults aged 20-55 years with self-reported stress, a sustained-release ashwagandha root extract (Prolanza, 300 mg) taken once daily for 90 days improved stress levels, sleep quality, serum cortisol, psychological well-being, memory, and focus compared to placebo [35]. Each capsule held 15 mg of withanolides [42].
In 54 adults with mild to moderate stress and anxiety, a daily tablet of 500 mg ashwagandha root extract (Shagandha, 2.5% withanolides) with 5 mg piperine for 60 days improved stress, anxiety and quality of life scores, multitasking, and concentration compared to placebo [36].
At the University of Colorado, 60 students (ages 18-50) who took 700 mg/day of a root extract for 30 days reported more energy, mental clarity and better sleep than those on placebo [37]. NIH adds that each capsule held 2.5 mg of withanolides and that the ashwagandha group more often described their stress as manageable [42].
Stress and Cortisol
In 58 stressed adults who completed an 8-week trial, a root extract at 125 mg or 300 mg twice daily lowered perceived stress and serum cortisol more than placebo, and sleep quality improved [17].
In an 8-week trial with 98 adults in the final analysis, an aqueous root and leaf extract taken at one of three daily doses (125 mg, 250 mg, 500 mg) reduced mild to moderate chronic stress [20].
In overweight or mildly obese adults aged 40-75 years with high stress and fatigue, Witholytin (200 mg twice daily) taken for 12 weeks lowered fatigue but not perceived stress, compared with placebo [39]. NIH notes 120 participants, mean age 54-55 years, and an extract containing 1.5% withanolides [42].
In 43 women and 17 men with perceived stress, NooGandha at 225 mg/day or 400 mg/day, taken for 30 days, did not beat placebo on self-reported anxiety, depression, stress, or food cravings, though the ashwagandha groups often did better on cognitive tests and the 225 mg/day group had lower salivary cortisol over time [23].
Reviews suggest ashwagandha may act mainly through the hypothalamic-pituitary-adrenal (HPA) axis and the sympathetic nervous system, as well as GABA and serotonin pathways [14, 31].
Sleep
A small number of studies suggest ashwagandha extract may improve several aspects of sleep, especially in people with insomnia [42].
Meta-analysis: A 2021 meta-analysis of 5 randomized trials with 400 participants found a small but significant effect on overall sleep (SMD -0.59, 95% CI -0.75 to -0.42) [41]. Effects were larger in adults with insomnia, at doses of at least 600 mg/day, and with treatment of at least 8 weeks [41]. All the trials were conducted in India [42].
Individual trials:
In 60 adults with insomnia, a root extract taken at 300 mg twice a day for 10 weeks shortened the time to fall asleep more than placebo (p = 0.019) and improved sleep efficiency, sleep quality and anxiety scores [43].
In 80 adults, half of them with insomnia, a root extract for 8 weeks improved sleep, with larger gains in those with insomnia [5]. NIH identifies the extract as KSM-66, two 300 mg capsules a day standardized to more than 5% withanolides [42].
A study of 150 healthy adults with non-restorative sleep found that Shoden at 120 mg once daily for 6 weeks raised self-reported sleep quality scores by 72% (vs. 29% for placebo). Actigraphy showed better sleep efficiency, total sleep time, sleep latency and wake time after sleep onset, and participants also reported improved quality of life [45].
In 60 college students, 700 mg/day of full-spectrum ashwagandha root extract for 30 days improved restorative sleep scores (58.4 vs. 48.2 with placebo) and lowered food cravings [46].
Cognitive Function
Evidence for cognitive enhancement is mixed, with gains on some tests but not others in small trials.
In a crossover trial in 20 healthy men, an aqueous root and leaf extract (two 250 mg capsules twice daily) for 14 days improved reaction times on several tests compared with placebo [47].
In 50 adults with mild cognitive impairment, root extract at 300 mg twice daily for 8 weeks improved immediate and general memory, as well as attention, executive function, and processing speed, more than placebo [48].
In adults aged 30-75 years with self-reported cognitive and energy problems (60 per group), root extract at 600 mg/day for 8 weeks improved episodic and working memory and the accuracy of attention more than placebo [49].
In 59 healthy young adults, 225 mg of a liposomal root and leaf extract improved some measures of memory, attention, and executive function, both an hour after a single dose and after 30 days of daily use [24].
Testosterone and Male Reproductive Health
A 2021 systematic review of herbs found that ashwagandha root and root/leaf extracts were one of two herbal extracts with positive effects on testosterone in men [13].
Individual trials:
In 46 men with low sperm counts, a full-spectrum root extract at 675 mg/day in three doses for 90 days increased sperm count (+167%), semen volume (+53%), and motility (+57%) from baseline, with minimal change on placebo; hormone levels also improved more than with placebo [56].
In 57 young men starting resistance training, root extract at 300 mg twice daily for 8 weeks raised testosterone more than placebo (96.2 ng/dL vs. 18.0 ng/dL) [57].
In a crossover trial in overweight men with mild fatigue, aged 40-70, Shoden (21 mg withanolide glycosides a day) for 8 weeks produced a 14.7% greater increase in testosterone than placebo, but no difference from placebo in vigor, fatigue, sexual well-being, cortisol, or estradiol [58].
In 76 healthy men aged 30-50 years, root extract at 300 mg twice daily for 8 weeks improved sexual desire and erectile function scores more than placebo, with a 36% rise in ejaculate volume, a 38% rise in total sperm count and an 87% rise in sperm motility [59].
In a 12-month observational study of 191 healthy adults taking a standardized root extract, free and total testosterone rose [60].
Sexual Function in Women
In a pilot trial in 50 healthy women, root extract at 300 mg twice daily for 8 weeks improved overall sexual function, arousal, lubrication, orgasm, and satisfaction scores more than placebo [19].
Peri- and Postmenopausal Symptoms
Three trials have tested ashwagandha for menopausal symptoms.
In a 24-week trial in postmenopausal women aged 40-55, groups given ashwagandha extract at 500 mg or 250 mg (in a six-arm trial that also tested shatavari and a combination) had lower markers of bone turnover than placebo [62].
In 91 perimenopausal women who completed an 8-week trial, root extract at 300 mg twice daily reduced menopause symptom scores, raised estradiol, and lowered FSH and LH compared with placebo; testosterone did not change [63].
In 60 women aged 45-55 years, an ashwagandha root extract taken for 56 days reduced menopause symptom scores, hot flash events, and perceived stress more than placebo [64].
Physical Performance
Small early trials suggested gains in strength and aerobic fitness, but the most recent controlled trial found no added benefit for aerobic capacity [106].
In a 2010 trial in healthy young adults, 10 people took 500 mg/day of a root extract for 8 weeks, and their velocity, power, and VO2 max increased [65].
Among 38 men who were recreationally active and doing resistance training, Sensoril at 500 mg/day for 12 weeks increased squat and bench press strength more than placebo [66].
In 50 healthy athletic adults, root extract at 300 mg twice daily for 8 weeks improved VO2 max and recovery scores more than placebo [67].
In the trial of 57 young men described above, ashwagandha also produced larger gains in muscle strength and size and a larger fall in body fat percentage than placebo [57].
In 56 team sports athletes in pre-season training, root extract at 600 mg/day for 42 days improved perceived recovery in women and countermovement jump in men; pull-ups improved in men in both the ashwagandha and placebo groups [68].
In professional female footballers (15 per group), 600 mg/day of root extract for 28 days improved total quality recovery and perceived sleep quality compared with placebo [69].
A 2021 Bayesian meta-analysis of 12 trials found ashwagandha more effective than placebo for physical performance measures in healthy adults of both sexes, but called for more comparable studies [70]. A 2020 meta-analysis of 4 trials (142 participants) found a higher VO2 max with ashwagandha (mean difference 3.00, 95% CI from 0.18 to 5.82), with high heterogeneity [105].
In the 2025 trial Brad discusses, healthy non-athlete men took 600 mg daily of ashwagandha or placebo during 8 weeks of rowing HIIT; aerobic capacity and blood measures improved equally in both groups [106].
Body Weight and Metabolism
In 52 adults under chronic stress, root extract at 300 mg twice daily for 8 weeks improved perceived stress, food cravings, serum cortisol, body weight, and BMI compared with placebo [71].
Anti-inflammatory Effects and Joint Pain
In 60 people with knee pain, an aqueous root and leaf extract at 250 mg or 125 mg twice daily for 12 weeks reduced pain, stiffness, and disability scores more than placebo; the 250 mg dose worked from 4 weeks, and both doses were well tolerated [72].
Thyroid Function
Ashwagandha may raise thyroid hormone levels [42]. That could help subclinical hypothyroidism but may call for caution in people prone to an overactive thyroid [74].
A study of 50 adults with subclinical hypothyroidism found that root extract at 600 mg/day for 8 weeks improved TSH, T3 and T4 compared with placebo [73]. NIH describes the dose as 300 mg twice daily and the effect as lower TSH with higher T3 and T4 [42].
In an 8-week placebo-controlled trial in 60 people with bipolar disorder, all 3 ashwagandha-treated patients with abnormal thyroid tests had rises in T4 [114]. NIH describes the extract as a standardized root and leaf extract at 500 mg/day, and the increases as small [42].
So ashwagandha could alter thyroid tests and might interact with thyroid medicines, even in people with normal thyroid function (see Safety section) [42, 74].
Schizophrenia
In 66 patients with worsening schizophrenia or schizoaffective disorder, a standardized extract at 1,000 mg/day added to antipsychotic medicine for 12 weeks reduced negative, general, and total symptoms more than placebo, but not positive symptoms (hallucinations, delusions); perceived stress also improved [75]. Side effects were mild to moderate; sleepiness, stomach discomfort, and loose stools occurred more often with ashwagandha than with placebo [75].
Adjunctive Use in Psychiatric Conditions
In 40 adults diagnosed with generalized anxiety disorder who were already taking SSRIs, root extract at 1 g a day for six weeks reduced Hamilton anxiety scores by 14 units, against 8 units with placebo, and no adverse effects were seen [34].
4. Recommended Dosing
By Indication
No universal recommended dose exists. The table lists daily doses used in trials described above.
| Indication | Daily Dose Used in Trials | Evidence Strength |
|---|---|---|
| Generalized anxiety disorder | 300-600 mg/day root extract (5% withanolides) | Provisional WFSBP/CANMAT recommendation [42] |
| Stress and cortisol reduction | 125-600 mg/day root or root and leaf extract | Several small RCTs, some negative [17, 20, 23, 39] |
| Sleep improvement | 600 mg/day root extract; or 120 mg Shoden | Meta-analysis: small effect, larger at 600 mg/day or more [41, 45] |
| Cognitive function | 600 mg/day root extract | Few small RCTs; mixed results [48, 49] |
| Testosterone and fertility (men) | 300 mg twice daily, or 675 mg/day, root extract | Small RCTs [56, 57, 59] |
| Physical performance | 500-600 mg/day root extract | Mixed; the latest trial was negative [66, 67, 106] |
| Menopausal symptoms | 300 mg twice daily root extract | Small RCTs [63] |
| Joint pain (osteoarthritis) | 250 mg or 125 mg twice daily aqueous root and leaf extract | One RCT [72] |
Practical Dosing Guidance
Extract vs. root powder: The WFSBP/CANMAT recommendation specifically applies to extracts standardized to 5% withanolides [42].
Duration: Most trials lasted 6 to 12 weeks. Ashwagandha appears well tolerated for up to about 3 months, but its long-term safety is not known [42]. A 12-month observational study in 191 healthy adults recorded only mild adverse events [60].
5. Safety and Side Effects
General Tolerability
Ashwagandha appears well tolerated for up to about 3 months [42]. Common side effects are mild and include stomach upset, loose stools, nausea, and drowsiness [42]. A review of 30 human studies listed somnolence, epigastric pain and loose stools as the most common adverse events [79]. Increased heart rate variability has also been reported [39, 42]. Evidence on long-term safety beyond 3 months is limited [42]. In a 12-month observational study of 191 healthy adults, 18 mild adverse events resolved without treatment, and liver enzymes did not change meaningfully [60].
Liver Injury
Rare but serious liver injury has been reported with ashwagandha [42, 81, 85].
Five people (3 men and 2 women, aged 21 to 62) developed jaundice with nausea, lethargy, itching, and abdominal discomfort after a latency of 2-12 weeks; liver tests returned to normal within 1-5 months in four of them, and none developed liver failure [81]. Their daily doses ranged from 450 to 1,350 mg, taken for 1 week to 4 months [42].
One 39-year-old woman had jaundice and nausea after taking an over-the-counter supplement with ashwagandha root extract; a liver biopsy showed acute cholestatic hepatitis with confluent necrosis [84].
In a series of 8 people from India with liver injury from single-ingredient ashwagandha products, 5 had chronic liver disease; 3 of them presented with acute-on-chronic liver failure, and all 3 died [85]. Chemical analysis found no adulteration or contamination [85]. Acute liver failure requiring a liver transplant has also been reported [107]. A 2024 review notes that most herbal liver injuries of this kind resolve on their own but can progress to acute liver failure with high mortality [108].
A 2017 case of a 20-year-old man in Japan who developed liver dysfunction and hyperbilirubinemia while using ashwagandha in combination with multiple antianxiety drugs was also reported [42, 86].
If your skin or eyes turn yellow, or you develop itching, nausea or unusual tiredness while taking ashwagandha, stop taking it and see a doctor promptly [42, 81].
Recommendation: The authors of this series warn that ashwagandha liver injury can lead to acute-on-chronic liver failure with high mortality in people with existing liver disease, and they call for educating the public to avoid potentially toxic herbal supplements [85]. People with liver disease may be safest avoiding ashwagandha unless their doctor advises otherwise.
Thyroid Effects
Ashwagandha may raise thyroid hormone levels, which may help subclinical hypothyroidism but poses risks for others [42, 73]. People with a thyroid condition or on thyroid medicine should ask their doctor before taking it.
NIH describes three case reports of thyrotoxicosis (too much thyroid hormone) in women aged 32 to 73 years taking ashwagandha extract; one involved an unusually high dose (1,950 mg/day for more than 2 months), and stopping resolved the symptoms in all three [42, 88]. In one, a 32-year-old woman developed it after raising her dose of ashwagandha capsules [87]. A 47-year-old man developed painless thyroiditis about 2 months after starting ashwagandha and improved after stopping [89].
Denmark banned ashwagandha in 2023 after a risk assessment raised concerns about thyroid and sex hormone effects and possible miscarriage [42, 90]. The French Agency for Food, Environmental, and Occupational Health and Safety (ANSES) recommended against use by pregnant and breastfeeding women and people with endocrine disorders [42, 91].
Adrenal Effects
A 2026 case report described a 55-year-old woman who took about 950 mg of ashwagandha daily for over a year and developed adrenal insufficiency (suppressed natural cortisol production); at a three-month follow-up after stopping it had not recovered, and she still needed hydrocortisone [109].
Pregnancy and Reproductive Concerns
Some experts advise against ashwagandha use during pregnancy because some reports suggested it could cause miscarriage [42, 93, 94]. However, the American Herbal Pharmacopoeia (AHP) has stated their 2000 monograph has been misrepresented and that there is no evidence ashwagandha root causes abortions [42, 95]. Ashwagandha might not be safe during pregnancy or breastfeeding [42]. Because it may raise testosterone, it might also not be safe for men with hormone-sensitive prostate cancer [42].
Other Safety Concerns
Blood sugar: In 6 people with mild type 2 diabetes, ashwagandha root powder for 30 days lowered blood glucose about as much as an oral diabetes drug [96]. Ashwagandha might interact with diabetes medicines, so check with your doctor before combining them [42]. If someone with diabetes is unconscious, having a seizure, or cannot swallow safely, call your local emergency number (111 in NZ, 000 in Australia, 911 in the US, 999 in the UK). Do not give food or drink by mouth.
Blood pressure: Ashwagandha might interact with blood pressure medicines [42].
Cardiac rhythm: A review of heart toxicity case reports lists ashwagandha among the herbs linked to heart problems [112]. In one case, a 73-year-old woman who had taken ashwagandha root extract for two years as self-treatment for hypothyroidism developed supraventricular tachycardia, a fast heart rhythm, with thyrotoxicosis, and her symptoms resolved after she stopped it [113]. If you notice a racing heartbeat while taking it, stop it and see a doctor [113].
Skin reactions: A 28-year-old man taking 5 g of ashwagandha a day for 10 days felt burning and itching, and the skin of his penis became discolored, a fixed drug eruption; a later 1 g test dose brought it back within 12 hours [98].
Withdrawal effects: A 2025 case report described a 20-year-old man with a fast heart rate, insomnia, and anxiety after he abruptly stopped ashwagandha extract (600 mg/day); a return of underlying anxiety could also explain it [110].
6. Drug Interactions
Ashwagandha might interact with thyroid hormone, diabetes and blood pressure medicines, immunosuppressants, and sedatives [42]. A review found no inhibition of the liver enzymes CYP3A4 and CYP2D6 [79].
| Medication Class | Interaction | Clinical Concern |
|---|---|---|
| Sedatives/Benzodiazepines | Ashwagandha can cause drowsiness | May add to sedation [42] |
| Thyroid medications (levothyroxine) | Ashwagandha may raise thyroid hormone levels | Possible excess thyroid hormone; thyrotoxicosis has been reported [42, 87] |
| Immunosuppressants (tacrolimus, cyclophosphamide) | Listed as a possible interaction by NIH | A case report links ashwagandha to kidney transplant rejection [42, 99] |
| Antidepressants (sertraline, escitalopram, paroxetine) | A root extract with piperine raised blood serotonin in one trial [101] | Adverse events have been reported with these combinations [111] |
| Antihypertensives | Ashwagandha may add to blood pressure lowering | Possible interaction [42] |
| Antidiabetic medications | May reduce blood glucose | Possible low blood sugar when combined [42, 96] |
| Blood thinners (warfarin, aspirin, clopidogrel) | Withaferin A, an ashwagandha compound, slowed clotting in laboratory and animal studies [102] | Human relevance unknown; ask your doctor first |
| Anesthesia | Ashwagandha can cause drowsiness [42] | Tell your surgical team that you take it |
In one trial, an ashwagandha root extract with piperine raised blood serotonin [101]. If you take prescription medicines, check with your doctor or pharmacist before starting.
A published case report links ashwagandha to kidney transplant rejection [99].
7. Dietary Sources
Ashwagandha is not a nutrient found in common foods. Supplements use the root of the Withania somnifera plant, and some add leaf [42].
Products vary widely in withanolide content and in how much leaf they contain [25]. Brad suggests choosing a product with independent testing, for example one tested by consumerlab.com (Brad, 15 Oct 2025).
8. References
[1] Mandlik Ingawale DS, Namdeo AG. Pharmacological evaluation of Ashwagandha highlighting its healthcare claims, safety, and toxicity aspects. J Diet Suppl. 2021;18:183-226. PubMed
[2] Panossian AG, Efferth T, Shikov AN, et al. Evolution of the adaptogenic concept from traditional use to medical systems. Med Res Rev. 2021;41:630-703. PubMed
[3] Gerontakos SE, Casteleijn D, Shikov AN, Wardle J. A Critical Review to Identify the Domains Used to Measure the Effect and Outcome of Adaptogenic Herbal Medicines. Yale J Biol Med. 2020;93:327-46. PubMed
[5] Langade D, Thakare V, Kanchi S, Kelgane S. Clinical evaluation of the pharmacological impact of ashwagandha root extract on sleep in healthy volunteers and insomnia patients. J Ethnopharmacol. 2021;264:113276. PubMed
[9] Lopresti AL, Smith SJ. Ashwagandha (Withania somnifera) for the treatment and enhancement of mental and physical conditions: A systematic review of human trials. Journal of Herbal Medicine. 2021;28:100434.
[10] Siddiqui S, Ahmed N, Goswami M, et al. DNA damage by Withanone as a potential cause of liver toxicity observed for herbal products of Withania somnifera (Ashwagandha). Curr Res Toxicol. 2021;2:72-81. PubMed
[13] Smith SJ, Lopresti AL, Teo SYM, Fairchild TJ. Examining the Effects of Herbs on Testosterone Concentrations in Men: A Systematic Review. Adv Nutr. 2021;12:744-65. PubMed
[14] Speers AB, Cabey KA, Soumyanath A, Wright KM. Effects of Withania somnifera on Stress and the Stress-Related Neuropsychiatric Disorders Anxiety, Depression, and Insomnia. Curr Neuropharmacol. 2021;19:1468-95. PubMed
[16] Sarris J, Ravindran A, Yatham LN, et al. Clinician guidelines for the treatment of psychiatric disorders with nutraceuticals and phytoceuticals: The WFSBP and CANMAT Taskforce. World J Biol Psychiatry. 2022;23:424-55. PubMed
[17] Salve J, Pate S, Debnath K, Langade D. Adaptogenic and Anxiolytic Effects of Ashwagandha Root Extract in Healthy Adults: A Double-blind, Randomized, Placebo-controlled Clinical Study. Cureus. 2019;11:e6466. PubMed
[19] Dongre S, Langade D, Bhattacharyya S. 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
[20] Pandit S, Srivastav AK, Sur TK, et al. Effects of Withania somnifera Extract in Chronically Stressed Adults: A Randomized Controlled Trial. Nutrients. 2024;16. PubMed
[23] Remenapp A, Coyle K, Orange T, et al. Efficacy of Withania somnifera supplementation on adult's cognition and mood. J Ayurveda Integr Med. 2022;13:100510. PubMed
[24] Leonard M, Dickerson B, Estes L, et al. Acute and Repeated Ashwagandha Supplementation Improves Markers of Cognitive Function and Mood. Nutrients. 2024;16. PubMed
[25] Avula B, Katragunta K, Tatapudi KK, et al. A Comparison of British and US Pharmacopoeia Standards for Quality of Ashwagandha Dietary Supplements in Commerce. Phytother Res. 2026;40:4833-4844. PubMed
[27] Arumugam V, Vijayakumar V, Balakrishnan A, et al. Effects of Ashwagandha (Withania Somnifera) on stress and anxiety: A systematic review and meta-analysis. Explore (NY). 2024;20:103062. PubMed
[28] Akhgarjand C, Asoudeh F, Bagheri A, 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;36:4115-4124. PubMed
[30] Cooley K, Szczurko O, Perri D, et al. Naturopathic care for anxiety: a randomized controlled trial ISRCTN78958974. PLoS One. 2009;4:e6628. PubMed
[31] Lopresti AL, Smith SJ, Malvi H, Kodgule R. An investigation into the stress-relieving and pharmacological actions of an ashwagandha extract. Medicine (Baltimore). 2019;98:e17186. PubMed
[32] Mishra DN, Kumar M. Shoden promotes Relief from stress and anxiety: A randomized, double-blind, placebo-controlled study on healthy subjects with high stress levels. Heliyon. 2024;10:e36885. PubMed
[34] Fuladi S, Emami SA, Mohammadpour AH, et al. Assessment of the efficacy of Withania somnifera root extract in patients with generalized anxiety disorder. Curr Rev Clin Exp Pharmacol. 2021;16:191-6. PubMed
[35] Gopukumar K, Thanawala S, Somepalli V, et al. Efficacy and Safety of Ashwagandha Root Extract on Cognitive Functions in Healthy, Stressed Adults. Evid Based Complement Alternat Med. 2021;2021:8254344. PubMed
[36] Majeed M, Nagabhushanam K, Mundkur L. A standardized Ashwagandha root extract alleviates stress, anxiety, and improves quality of life. Medicine (Baltimore). 2023;102:e35521. PubMed
[37] Baker C, Kirby JB, O'Connor J, et al. The Perceived Impact of Ashwagandha on Stress, Sleep Quality, Energy, and Mental Clarity for College Students. J Med Food. 2022;25:1095-101. PubMed
[39] Smith SJ, Lopresti AL, Fairchild TJ. Exploring the efficacy and safety of Witholytin in adults experiencing high stress and fatigue. J Psychopharmacol. 2023;37:1091-104. PubMed
[41] Cheah KL, Norhayati MN, Husniati Yaacob L, Abdul Rahman R. Effect of Ashwagandha extract on sleep: A systematic review and meta-analysis. PLoS One. 2021;16:e0257843. PubMed
[42] NIH ODS. Ashwagandha: Is it helpful for stress, anxiety, or sleep? -- Health Professional Fact Sheet. Updated May 2, 2025. https://ods.od.nih.gov/factsheets/Ashwagandha-HealthProfessional/
[43] Langade D, Kanchi S, Salve J, et al. Efficacy and Safety of Ashwagandha (Withania somnifera) Root Extract in Insomnia and Anxiety: A Double-blind, Randomized, Placebo-controlled Study. Cureus. 2019;11:e5797. PubMed
[45] Deshpande A, Irani N, Balkrishnan R, Benny IR. A randomized, double blind, placebo controlled study to evaluate the effects of ashwagandha extract on sleep quality. Sleep Med. 2020;72:28-36. PubMed
[46] O'Connor J, Lindsay K, Baker C, et al. The Impact of Ashwagandha on Stress, Sleep Quality, and Food Cravings in College Students: Quantitative Analysis of a Double-Blind Randomized Control Trial. J Med Food. 2022;25:1086-1094. PubMed
[47] Pingali U, Pilli R, Fatima N. Effect of standardized aqueous extract of Withania somnifera on tests of cognitive and psychomotor performance in healthy human participants. Pharmacognosy Res. 2014;6:12-8. PubMed
[48] Choudhary D, Bhattacharyya S, Bose S. Efficacy and Safety of Ashwagandha (Withania somnifera (L.) Dunal) Root Extract in Improving Memory and Cognitive Functions. J Diet Suppl. 2017;14:599-612. PubMed
[49] Kale S, Lopresti A, Suri R, et al. Safety and Efficacy of Ashwagandha Root Extract on Cognition, Energy and Mood Problems in Adults: Prospective, Randomized, Placebo-Controlled Study. J Psychoactive Drugs. 2026;58:45-57. PubMed
[56] Ambiye VR, Langade D, Dongre S, et al. Clinical Evaluation of the Spermatogenic Activity of the Root Extract of Ashwagandha (Withania somnifera) in Oligospermic Males: A Pilot Study. Evid Based Complement Alternat Med. 2013;2013:571420. PubMed
[57] Wankhede S, Langade D, Joshi K, et al. Examining the effect of Withania somnifera supplementation on muscle strength and recovery: a randomized controlled trial. J Int Soc Sports Nutr. 2015;12:43. PubMed
[58] Lopresti AL, Drummond PD, Smith SJ. A Randomized, Double-Blind, Placebo-Controlled, Crossover Study Examining the Hormonal and Vitality Effects of Ashwagandha in Aging, Overweight Males. Am J Mens Health. 2019;13:1557988319835985. PubMed
[59] Khanna A, Khanna M, Panchal P. Efficacy and safety of ashwagandha root extract on sexual health in healthy Men: a prospective, randomized, double-blind, placebo-controlled study. Front Reprod Health. 2026;8:1774098. PubMed
[60] Salve J, Kale S, Prajapati BL, et al. Safety of 12-Months Administration of Ashwagandha (Withania somnifera) Standardized Root Extract in Healthy Adults: A Prospective, Observational Study. Phytother Res. 2026;40:4802-4812. PubMed
[62] Pingali U, Nutalapati C, Wang Y. Ashwagandha and Shatavari Extracts Dose-Dependently Reduce Menopause Symptoms, Vascular Dysfunction, and Bone Resorption in Postmenopausal Women. J Menopausal Med. 2025;31:21-34. PubMed
[63] Gopal S, Ajgaonkar A, Kanchi P, et al. Effect of an ashwagandha (Withania Somnifera) root extract on climacteric symptoms in women during perimenopause. J Obstet Gynaecol Res. 2021;47:4414-4425. PubMed
[64] Vani I, Muralidhar G, Rao BS. A prospective, randomized, double-blind, placebo-controlled study on efficacy and safety of Ashwagandha root extract (Withania somnifera) for managing menopausal symptoms in women. Front Reprod Health. 2025;7:1647721. PubMed
[65] Sandhu JS, Shah B, Shenoy S, et al. Effects of Withania somnifera (Ashwagandha) and Terminalia arjuna (Arjuna) on physical performance and cardiorespiratory endurance in healthy young adults. Int J Ayurveda Res. 2010;1:144-9. PubMed
[66] Ziegenfuss TN, Kedia AW, Sandrock JE, et al. Effects of an Aqueous Extract of Withania somnifera on Strength Training Adaptations and Recovery: The STAR Trial. Nutrients. 2018;10. PubMed
[67] Tiwari S, Gupta SK, Pathak AK. A double-blind, randomized, placebo-controlled trial on the effect of Ashwagandha root extract in improving cardiorespiratory endurance and recovery in healthy athletic adults. J Ethnopharmacol. 2021;272:113929. PubMed
[68] Coope OC, Otaegui E, Suárez M, et al. Ashwagandha Root Extract Stabilises Physiological Stress Responses in Male and Female Team Sports Athletes During Pre-Season Training. Nutrients. 2026;18. PubMed
[69] Coope OC, Reales Salguero A, Spurr T, et al. Effects of Root Extract of Ashwagandha (Withania somnifera) on Perception of Recovery and Muscle Strength in Female Athletes. Eur J Sport Sci. 2025;25:e12265. PubMed
[70] Bonilla DA, Moreno Y, Gho C, et al. Effects of Ashwagandha (Withania somnifera) on Physical Performance: Systematic Review and Bayesian Meta-Analysis. J Funct Morphol Kinesiol. 2021;6. PubMed
[71] Choudhary D, Bhattacharyya S, Joshi K. Body Weight Management in Adults Under Chronic Stress Through Treatment With Ashwagandha Root Extract: A Double-Blind, Randomized, Placebo-Controlled Trial. J Evid Based Complementary Altern Med. 2017;22:96-106. PubMed
[72] Ramakanth GS, Uday Kumar C, Kishan PV, et al. A randomized, double blind placebo controlled study of efficacy and tolerability of Withaina somnifera extracts in knee joint pain. J Ayurveda Integr Med. 2016;7:151-157. PubMed
[73] Sharma AK, Basu I, Singh S. Efficacy and Safety of Ashwagandha Root Extract in Subclinical Hypothyroid Patients. J Altern Complement Med. 2018;24:243-8. PubMed
[74] Gannon JM, Forrest PE, Roy Chengappa KN. Subtle changes in thyroid indices during a placebo-controlled study of Withania somnifera in persons with bipolar disorder. J Ayurveda Integr Med. 2014;5:241-5. PubMed
[75] Chengappa KNR, Brar JS, Gannon JM, et al. Adjunctive Use of a Standardized Extract of Withania somnifera (Ashwagandha) to Treat Symptom Exacerbation in Schizophrenia: A Randomized, Double-Blind, Placebo-Controlled Study. J Clin Psychiatry. 2018;79. PubMed
[79] Tandon N, Yadav SS. Safety and clinical effectiveness of Withania somnifera root in human ailments. J Ethnopharmacol. 2020;255:112768. PubMed
[81] Bjornsson HK, Bjornsson ES, Avula B, et al. Ashwagandha-induced liver injury: A case series from Iceland and the US DILIN. Liver Int. 2020;40:825-9. PubMed
[84] Ireland PJ, Hardy T, Burt AD, Donnelly MC. Drug-induced hepatocellular injury due to herbal supplement ashwagandha. J R Coll Physicians Edinb. 2021;51:363-5. PubMed
[85] Philips CA, Valsan A, Theruvath AH, et al. Ashwagandha-induced liver injury -- A case series from India and literature review. Hepatol Commun. 2023;7. PubMed
[86] Inagaki K, et al. A case of drug-induced liver injury with prolonged severe intrahepatic cholestasis induced by Ashwagandha. Kanzo. 2017;58:448-54.
[87] van der Hooft CS, Hoekstra A, Winter A, et al. [Thyrotoxicosis following the use of ashwagandha]. Ned Tijdschr Geneeskd. 2005;149:2637-8. PubMed
[88] Curry KM, McNeil LE, Flores A, Fuks J. Thyrotoxicosis with Ashwagandha: A Case Report. SSRN. 2019.
[89] Hayashi M, Hamada H, Azuma SI, et al. Painless Thyroiditis by Withania somnifera (Ashwagandha). Cureus. 2024;16:e55352. PubMed
[90] McKeown M. Why did Denmark ban Ashwagandha? McGill University, Office for Science and Society, 2023.
[91] ANSES. Avis relatif aux risques lies a l'utilisation des preparations de Withania somnifera dans les complements alimentaires. 2024.
[93] American Herbal Products Association. AHPA Botanical Safety Handbook, 2nd edition. Boca Raton, FL: CRC Press; 2013.
[94] National Center for Complementary and Integrative Health. Ashwagandha. 2023.
[95] American Herbal Pharmacopoeia. AHP Responds to Claims of Ashwagandha Abortifacient Effects. 2024.
[96] Andallu B, Radhika B. Hypoglycemic, diuretic and hypocholesterolemic effect of winter cherry (Withania somnifera, Dunal) root. Indian J Exp Biol. 2000;38:607-9. PubMed
[98] Sehgal VN, Verma P, Bhattacharya SN. Fixed-drug eruption caused by ashwagandha (Withania somnifera): a widely used Ayurvedic drug. Skinmed. 2012;10:48-9. PubMed
[99] Sriperumbuduri S, Umar MS, Lajoie-Starkell G, et al. Ashwagandha and Kidney Transplant Rejection. Kidney Int Rep. 2020;5:2375-2378. PubMed
[101] Majeed M, Nagabhushanam K, Murali A, et al. A Standardized Withania somnifera Root Extract with Piperine Alleviates Anxiety and Depression by Increasing Serotonin Levels. J Integr Complement Med. 2024;30:459-68. PubMed
[102] Ku SK, Bae JS. Antiplatelet, anticoagulant, and profibrinolytic activities of withaferin A. Vascul Pharmacol. 2014;60:120-6. PubMed
[105] Pérez-Gómez J, Villafaina S, Adsuar JC, et al. Effects of Ashwagandha (Withania somnifera) on VO2max: A Systematic Review and Meta-Analysis. Nutrients. 2020;12. PubMed
[106] Ewa J, Klusiewicz A, Rębiś K, et al. Effects of an 8-week high intensity interval training (HIIT) and ashwagandha supplementation on aerobic capacity, muscle oxygenation and haematological parameters in healthy men. Biol Sport. 2025;42:129-139. PubMed
[107] Suryawanshi G, Abdallah M, Thomson M, et al. Ashwagandha-Associated Acute Liver Failure Requiring Liver Transplantation. Am J Ther. 2023;30:e80-e83. PubMed
[108] Philips CA, Theruvath AH. A comprehensive review on the hepatotoxicity of herbs used in the Indian (Ayush) systems of alternative medicine. Medicine (Baltimore). 2024;103:e37903. PubMed
[109] Javid J, Kunnuru SR, Anne B, et al. From herbal hope to hormonal havoc: chronic ashwagandha use and HPA axis suppression. Endocrinol Diabetes Metab Case Rep. 2026;2026. PubMed
[110] Holzman A, Brown AE, Kelley J, et al. Unmasking Potential Withdrawal Effects of Ashwagandha: A Case Report and Review. Cureus. 2025;17:e83577. PubMed
[111] Siwek M, Woroń J, Wrzosek A, et al. Harder, better, faster, stronger? Retrospective chart review of adverse events of interactions between adaptogens and antidepressant drugs. Front Pharmacol. 2023;14:1271776. PubMed
[112] Brown AC. Heart Toxicity Related to Herbs and Dietary Supplements: Online Table of Case Reports. Part 4 of 5. J Diet Suppl. 2018;15:516-55. PubMed
[113] Kamal HI, Patel K, Brdak A, et al. Ashwagandha as a Unique Cause of Thyrotoxicosis Presenting With Supraventricular Tachycardia. Cureus. 2022;14:e23494. PubMed
[114] Gannon JM, Forrest PE, Roy Chengappa KN. Subtle changes in thyroid indices during a placebo-controlled study of an extract of Withania somnifera in persons with bipolar disorder. J Ayurveda Integr Med. 2014;5:241-5. PubMed
