Is Ashwagandha Safe to Take?
Ashwagandha’s safety profile is supported by multiple published clinical trials and two comprehensive reviews. Mandlik Ingawale et al. (2021) published a pharmacological evaluation in the Journal of Dietary Supplements covering healthcare claims, safety, and toxicity aspects across the available literature (PMID: 32242751). Paul et al. (2021) published a comprehensive review in Biomedicine and Pharmacotherapy covering ethnopharmacology, pharmacotherapeutics, and toxicological aspects (PMID: 34649336). Both reviews concluded that standardized ashwagandha root extracts at recommended doses (300-600 mg/day) are generally safe for healthy adults in supplementation periods up to 12 weeks.
The safety picture changed in 2021-2024 as rare but serious hepatotoxicity cases were reported to pharmacovigilance databases. These cases shifted the risk assessment from “no known serious adverse effects” to “generally safe but with documented rare liver injury risk that requires awareness.”
What Are the Most Reported Hepatotoxicity Cases?
Rare liver injury cases associated with ashwagandha have been reported in post-market surveillance databases across multiple countries. First, case reports documented increased liver enzymes (ALT, AST) in patients taking ashwagandha-containing products, typically resolving after discontinuation. Second, most cases involved combination products where ashwagandha was one of several ingredients, making attribution difficult. Third, the absolute incidence rate appears very low relative to total market consumption (ashwagandha is one of the top 5 best-selling herbal supplements in the U.S.), but the signal is real and documented.
Risk factors for potential liver injury include pre-existing liver disease, concurrent use of other hepatotoxic supplements or medications, use of high-dose or unstandardized extracts, and prolonged use beyond the 8-12 week periods studied in clinical trials. Healthy adults at standard doses for standard durations face very low absolute risk based on available evidence, but baseline liver function and periodic monitoring are prudent for long-term users.
What Are the Common Side Effects?
Standardized ashwagandha root extract at 300-600 mg/day produces mild and infrequent side effects in most healthy adults based on safety data from multiple RCTs. First, gastrointestinal discomfort, including nausea, stomach upset, loose stools, or diarrhea, is the most commonly reported adverse effect across trials, affecting approximately 5-10% of participants. Taking ashwagandha with food reduces GI symptoms. Second, drowsiness or sedation occurs in a subset of users, consistent with ashwagandha’s GABA-ergic activity. This effect is a benefit for sleep-focused users but may impair daytime function at higher doses. Third, headache has been reported during the first 1-2 weeks of use and typically resolves without intervention. Fourth, upper abdominal pain was documented in the Chandrasekhar et al. (2012) trial but at comparable rates in both treatment and placebo groups (PMID: 23439798).
Does Ashwagandha Affect Thyroid Hormone Levels?
Sharma et al. (2018) published a double-blind, randomized placebo-controlled trial in 50 subjects with subclinical hypothyroidism (PMID: 28829155). First, 600 mg/day of ashwagandha root extract for 8 weeks significantly increased serum T3 and T4 levels. Second, TSH levels decreased significantly compared to placebo. Third, these changes normalized thyroid function in subclinical hypothyroid patients, which was the intended therapeutic outcome of the trial.
The thyroid data creates a two-sided risk profile. For hypothyroid patients, ashwagandha may offer support (though this is a single unreplicated trial). For hyperthyroid patients or those with Graves’ disease, ashwagandha could worsen the condition by further increasing already-high thyroid hormones. For people taking levothyroxine or other thyroid medications, ashwagandha may create unpredictable interactions with dosing. Any thyroid condition warrants medical supervision before starting ashwagandha.
Wicinski et al. (2023) reviewed ashwagandha’s endocrine effects broadly and confirmed that thyroid hormone modulation is a consistent finding across studies, not an isolated result (PMID: 38003702).
Does Ashwagandha Interact with Medications?
Six drug categories warrant attention when considering ashwagandha supplementation. First, thyroid medications (levothyroxine, methimazole): ashwagandha alters thyroid hormone levels based on the Sharma et al. (2018) data, potentially requiring dose adjustments to prescribed medications. Second, sedative and anxiolytic medications (benzodiazepines, barbiturates, sleep aids): additive sedation risk from ashwagandha’s GABA-ergic activity could impair alertness and motor function. Third, immunosuppressant medications (cyclosporine, mycophenolate, azathioprine): ashwagandha may stimulate immune activity, potentially counteracting immunosuppressive therapy. Fourth, diabetes medications (metformin, insulin, sulfonylureas): ashwagandha may lower blood sugar, creating additive hypoglycemia risk. Fifth, antihypertensive medications: ashwagandha may lower blood pressure, requiring monitoring for additive effects. Sixth, testosterone replacement therapy: additive androgenic effect based on the Wankhede et al. (2015) and Lopresti et al. (2019) testosterone data.
| Drug Category | Interaction Concern | Action Required |
|---|---|---|
| Thyroid medications | Alters T3, T4, TSH levels | Monitor thyroid labs closely |
| Sedatives/anxiolytics | Additive sedation risk | Reduce ashwagandha dose or avoid |
| Immunosuppressants | May stimulate immune activity | Avoid without medical approval |
| Diabetes medications | Additive blood sugar lowering | Monitor glucose, hypoglycemia risk |
| Antihypertensives | Additive blood pressure lowering | Monitor BP |
| Testosterone therapy | Additive androgenic effect | Avoid without medical supervision |
Who Should Avoid Ashwagandha Entirely?
Nine population groups should not take ashwagandha without explicit medical clearance. First, pregnant women: ashwagandha has been classified as an abortifacient in Ayurvedic texts and animal data suggests potential teratogenic effects at high doses. Safety data during human pregnancy does not exist. Second, breastfeeding women: insufficient data on withanolide transfer to breast milk. Third, individuals with hyperthyroidism or Graves’ disease: ashwagandha increases thyroid hormones and could worsen hyperthyroid conditions. Fourth, people with autoimmune diseases (lupus, rheumatoid arthritis, multiple sclerosis, type 1 diabetes): ashwagandha may stimulate immune activity and exacerbate autoimmune flares. Fifth, individuals with active liver disease or high liver enzymes: rare hepatotoxicity cases increase risk for this population. Sixth, people scheduled for surgery: ashwagandha may affect blood pressure, blood sugar, and thyroid hormones during anesthesia. Discontinue at least 2 weeks before planned surgery. Seventh, children under 18: clinical trial data in pediatric populations is insufficient. Eighth, individuals taking immunosuppressant medications. Ninth, anyone with a known allergy to Solanaceae (nightshade) family plants, since ashwagandha belongs to this botanical family.
Does Ashwagandha Cause Hormonal Side Effects?
Ashwagandha measurably affects multiple hormonal pathways based on published clinical data. First, testosterone increase (96.2 ng/dL over placebo in the Wankhede et al. 2015 trial, PMID: 26609282) is a benefit for the target population but could theoretically worsen hormone-sensitive conditions. Women with PCOS or androgen-sensitive conditions should use caution. Second, cortisol reduction is the primary therapeutic mechanism but may cause issues for individuals with already-low cortisol (Addison’s disease, adrenal insufficiency). Third, thyroid hormone increases (T3, T4 rise, TSH decrease) is documented and clinically significant for thyroid-sensitive populations.
The hormonal effects are generally desirable at standard doses in appropriate populations (stressed adults, men seeking testosterone support). The risk arises when ashwagandha is taken by individuals with pre-existing hormonal conditions where these shifts are harmful.
What About Long-Term Safety?
Most published RCTs ran 8-12 weeks, providing solid short-term safety data. First, Raut et al. (2012) published an exploratory tolerability study that evaluated safety over an extended period without identifying new adverse effects (PMID: 23125505). Second, traditional Ayurvedic use spans thousands of years at root powder doses, providing historical (though non-controlled) safety precedent. Third, the rare hepatotoxicity cases reported in post-market surveillance represent the strongest argument for limiting continuous use duration or implementing cycling protocols (8-12 weeks on, 2-4 weeks off).
Long-term safety beyond 12 weeks of standardized extract use at clinical doses lacks dedicated trial coverage. For users intending to take ashwagandha continuously beyond 3 months, periodic liver function monitoring is a reasonable precaution.
What Is the Bottom Line on Ashwagandha Safety?
Standardized ashwagandha root extract at 300-600 mg/day for 8-12 weeks has a favorable safety profile for most healthy adults, supported by multiple clinical trials and comprehensive safety reviews (Mandlik Ingawale et al. 2021, PMID: 32242751 and Paul et al. 2021, PMID: 34649336). The most common side effects are mild GI discomfort and drowsiness. The most significant safety signals involve rare hepatotoxicity, thyroid hormone changes, and potential immune stimulation. Contraindications include pregnancy, hyperthyroidism, active liver disease, autoimmune conditions, and upcoming surgery. Using a standardized, third-party tested extract from a reputable brand at recommended doses for documented durations represents the lowest-risk approach.
For dosage information, see Ashwagandha Dosage. For benefits and evidence, see Ashwagandha Benefits.
References
- Mandlik Ingawale DS, Namdeo AG. Pharmacological evaluation of Ashwagandha highlighting its healthcare claims, safety, and toxicity aspects. J Diet Suppl. 2021, 18(2):183-226. PMID: 32242751.
- Paul S, et al. Withania somnifera (L.) Dunal (Ashwagandha): A comprehensive review on ethnopharmacology, pharmacotherapeutics, biomedicinal and toxicological aspects. Biomed Pharmacother. 2021, 143:112175. PMID: 34649336.
- Chandrasekhar K, Kapoor J, Anishetty S. A prospective, randomized double-blind, placebo-controlled study of safety and efficacy of ashwagandha root extract in reducing stress and anxiety in adults. Indian J Psychol Med. 2012, 34(3):255-262. PMID: 23439798.
- Sharma AK, Basu I, Singh S. Efficacy and Safety of Ashwagandha Root Extract in Subclinical Hypothyroid Patients. J Altern Complement Med. 2018, 24(3):243-248. PMID: 28829155.
- Wicinski M, et al. Can Ashwagandha Benefit the Endocrine System? A Review. Int J Mol Sci. 2023, 24(24):17389. PMID: 38003702.
- Wankhede S, Langade D, Joshi K, Sinha SR, Bhattacharyya S. Examining the effect of Withania somnifera supplementation on muscle strength and recovery: a randomized controlled trial. J Int Soc Sports Nutr. 2015, 12:43. PMID: 26609282.
- Raut AA, et al. Exploratory study to evaluate tolerability, safety, and activity of Ashwagandha in healthy volunteers. J Ayurveda Integr Med. 2012, 3(3):111-114. PMID: 23125505.