Is ashwagandha safe to take?
Moderate EvidenceIT DEPENDS
Ashwagandha is generally safe for most healthy adults when taken at standard doses (300-600mg/day) for up to 3 months. However, rare liver injury cases have been reported, and it should be avoided during pregnancy and by those with thyroid conditions.
The Verdict
Ashwagandha is generally safe for most healthy adults when taken at standard doses (300-600mg/day) for up to 3 months. However, rare liver injury cases have been reported, and it should be avoided during pregnancy and by those with thyroid conditions.
What the Evidence Shows
Ashwagandha (Withania somnifera) has a long history of traditional use and has been studied in numerous clinical trials. Most RCTs report mild or no adverse effects at doses up to 600mg/day for 8-12 weeks. Common side effects include mild GI upset, drowsiness, and headache. However, the FDA and international regulators have documented rare cases of liver injury (hepatotoxicity), prompting safety warnings in some countries. The herb can stimulate thyroid function, making it risky for those with hyperthyroidism or on thyroid medication. It may also lower blood sugar and blood pressure, potentially interacting with diabetes and hypertension medications. Pregnant women should avoid it due to potential abortifacient effects observed in animal studies. Long-term safety data beyond 3 months is limited.
Evidence Quality
3
Meta-Analyses
15
RCTs
8
Observational
Important Caveats
- ⚠️ Rare cases of liver injury (hepatotoxicity) have been reported to regulators worldwide
- ⚠️ Can stimulate thyroid function — avoid if you have hyperthyroidism or take thyroid medication
- ⚠️ May lower blood sugar and blood pressure — use caution with diabetes or BP medications
- ⚠️ Not safe during pregnancy due to potential abortifacient effects
- ⚠️ Long-term safety data beyond 3 months is limited
- ⚠️ Quality varies widely between brands — contaminants have been found in some products
Population Studied
Healthy adults in RCTs lasting 4-12 weeks; post-marketing surveillance data from general population
Dosage
Doses of 300-600mg/day of standardized extract appear safe for most adults; higher doses increase risk of side effects
Duration
Most safety data comes from trials lasting 8-12 weeks; long-term use beyond 3 months is less studied
Supporting Studies (3)
Safety and clinical effectiveness of Withania somnifera root extract
RCTRaut AA, Rege NN, Tadvi FM, et al. · Journal of Ayurveda and Integrative Medicine (2012)
In a dose-escalation study (750-1250mg/day), ashwagandha was well tolerated with no serious adverse events. Mild side effects included increased appetite and libido.
View paper (DOI) →A systematic review of the safety of ashwagandha
Meta-AnalysisTandon N, Yadav SS. · Journal of Ethnopharmacology (2020)
Review of 69 studies found ashwagandha generally well-tolerated with mild adverse effects (GI upset, drowsiness) at doses up to 1000mg/day.
View paper (DOI) →Efficacy and tolerability of ashwagandha root extract in the elderly for improvement of memory
RCTChoudhary D, Bhattacharyya S, Bose S. · Journal of Dietary Supplements (2017)
600mg/day for 8 weeks in elderly subjects showed no clinically significant adverse events; tolerability was comparable to placebo.
View paper (DOI) →Contradicting Studies (2)
Ashwagandha-associated liver injury: A case series from Iceland and worldwide
ObservationalBjörnsson HK, Björnsson ES, Avula B, et al. · Liver International (2020)
Reported 5 cases of liver injury in Iceland linked to ashwagandha supplements, with patterns suggesting idiosyncratic drug-induced liver injury.
Why this disagrees:
While rare, these documented liver injury cases indicate ashwagandha is not universally safe. The mechanism appears idiosyncratic (unpredictable individual reactions) rather than dose-dependent.
Herbal hepatotoxicity: a growing concern
ObservationalNavarro VJ, Khan I, Björnsson E, et al. · Hepatology (2017)
Ashwagandha was identified among herbal supplements associated with liver injury in the Drug-Induced Liver Injury Network registry.
Why this disagrees:
Population-level surveillance shows a small but real risk of liver injury that was not detected in controlled trials with limited participants.
Related Claims
Does ashwagandha increase testosterone in men?
Moderate EvidenceModerate evidence suggests ashwagandha may modestly increase testosterone levels in men, particularly those under physical or psychological stress. Effect sizes are typically 10-22% above baseline, but clinical significance for healthy young men remains uncertain.
Is ashwagandha effective for reducing anxiety?
Moderate EvidenceModerate evidence suggests ashwagandha (Withania somnifera) significantly reduces self-reported anxiety and stress symptoms compared to placebo, with effects comparable to some low-dose anxiolytics.
Is melatonin safe for long-term use?
Moderate EvidenceModerate evidence suggests melatonin is safe for short-to-medium term use (up to 3-6 months) with minimal side effects. Long-term safety data (>1 year) is limited but available studies show no major concerns.
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