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▸ Ashwagandha · Safety

Ashwagandha Side Effects: Real vs. Myth

Ashwagandha is well-tolerated in controlled trials — but it is not consequence-free, and the internet gets both the fears and the reassurances wrong. Here is every claimed side effect, checked against the evidence, with the three cautions that actually matter.

Updated July 2026 · 30 peer-reviewed sources · Free to cite (CC BY 4.0).

30 sources — every figure verified on PubMedIndependent — the rankings follow the data, not commissionsReviewed June 2026 · Methodology

Is ashwagandha safe? The bottom line

30
human trials reviewed — adverse events mild, no serious signal
12 mo
RCT at 600 mg/day — liver enzymes stayed stable
3
cautions that genuinely matter: liver, thyroid, pregnancy
Rare
idiosyncratic liver injury — mostly in pre-existing liver disease

The honest summary: in controlled trials ashwagandha is well tolerated, with side effects that are mild and comparable to placebo[13,1]. The reasons to be careful are specific rather than general — and they're below.

▸ 20-second self-check

Should you be cautious with ashwagandha?

Tick anything that applies to you:

No documented red flags for you — None of the documented contraindications apply. The standard clinical dose is 300–600 mg/day of a standardised extract, taken with food — and stop and see a doctor if you ever develop jaundice, dark urine, or itching.
NoteA quick self-check, not medical advice — the details on each risk are in the sections below. If you're clear, see our ranked picks.

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Common side effects

The most frequently reported effects in trials are mild GI upset (nausea, stomach discomfort) and drowsiness, with occasional headache — all self-resolving and no more common than on placebo[13,14]. Taking ashwagandha with food reduces the stomach upset, which is why the long-term safety trial dosed it after meals. Because it can be mildly sedating, many people take it in the evening.

Liver injury — the real, rare caveat

This is the caution worth taking seriously — and keeping in proportion. Clinically apparent ashwagandha-associated liver injury is rare and idiosyncratic: the US LiverTox database rates it a “likely but uncommon” cause of liver injury[21]. When it happens, it typically appears 2–12 weeks after starting, shows up as a cholestatic or mixed pattern with jaundice and itching, and usually resolves within 1–5 months of stopping[16]. In the largest case series, the severe and fatal outcomes occurred almost entirely in patients who already had chronic liver disease[17].

For context on the other side of the ledger: a 12-month observational study in 191 adults taking 600 mg/day kept average ALT and AST stable and inside the normal range[15]. So the honest framing is: most people's livers are unaffected, but a small number react idiosyncratically — so don't take ashwagandha if you have liver disease, and stop immediately and see a doctor if you develop jaundice, dark urine, pale stools, or itching. In the main Iceland/US case series, four of the five patients' liver tests normalised within 1–5 months of stopping[16].

Thyroid — a real interaction

Ashwagandha nudges thyroid hormones upward: in subclinical hypothyroid patients, 8 weeks significantly raised T3 and T4 and lowered TSH[18]. That can be beneficial there — but it is a genuine reason for caution if you take thyroid medication (levothyroxine and similar) or have an overactive thyroid, because the effect is additive and can push you toward over-replacement. In people with normal thyroid function, controlled trials show no meaningful change[14]. If you take thyroid medication, coordinate with your doctor before starting.

Pregnancy — avoid, as a precaution

Here the honest answer differs from the usual scare. The traditional claim that ashwagandha is an abortifacientisn't actually backed by solid primary evidence — a 2025 systematic review found the claim rests on citation distortion, and animal developmental studies were reassuring at high doses[19,20]. But there are no adequate human pregnancy safety studies, so the correct call is still to avoid ashwagandha in pregnancy and while breastfeeding — as a precaution because the safety data are absent, not because a strong harmful signal is proven.

Sedation & interactions

Ashwagandha acts partly through a GABA-ergic mechanism, which explains both its calming effect and its interaction profile[22]. Don't combine it with sedatives, benzodiazepines, sleep medication, or alcohol without medical supervision — the CNS-depressant effects are additive. Because it is mildly immunostimulating(it up-regulates a Th1 immune response in lab models), people with an autoimmune condition such as Hashimoto's, rheumatoid arthritis, lupus or MS should be cautious[23]. As a precaution, stop ashwagandha about two weeks before any scheduled surgery.

Beyond sedatives, national health authorities flag several medication interactions: because ashwagandha can lower blood sugar and blood pressure and can nudge up the immune response, it may add to the effect of anti-diabetic and blood-pressure medication and may oppose immunosuppressants (e.g. after a transplant)[30,29] — coordinate with your clinician if you take any of these. And because it modestly raises testosterone, NIH advises anyone with a hormone-sensitive cancer such as prostate cancer to avoid it — a precaution based on the hormone effect, not on any human outcome data[30,25].

Who should be cautious

Skip ashwagandha, or clear it with a clinician first, if you: are pregnant or breastfeeding; take thyroid medication or have hyperthyroidism; have chronic liver disease; have an autoimmune condition or a hormone-sensitive cancer; take sedatives, diabetes, blood-pressure or immunosuppressant medication; or have surgery scheduled. For everyone else, the trial record is reassuring — see what it actually does, and the full data report for every figure and source.

Myths vs. facts

The mythWhat the evidence showsSource
Ashwagandha boosts testosterone like a steroid The rise is real but indirect and modest (+14.7% in aging men; +96 vs +18 ng/dL with training) — it is downstream of the cortisol drop, not direct hormone stimulation, and it won't close a clinical deficiency.[3,4]
It destroys your liver Clinically apparent liver injury is rare and idiosyncratic; a 12-month observational study kept ALT/AST stable, and the severe cases clustered in people with pre-existing chronic liver disease.[15,16,17]
It's an abortifacient — definitely unsafe in pregnancy The abortifacient claim is a traditional one that primary evidence doesn't support (animal developmental data are reassuring). Still avoid it in pregnancy — as a precaution, because human safety data are absent.[19,20]
It's just Ayurvedic placebo 12+ placebo-controlled RCTs and multiple meta-analyses show real, reproducible effects on cortisol, sleep, and testosterone.[6,8]
You feel it instantly, like a sedative It is not benzodiazepine sedation. Sleep shifts first (2–3 weeks); stress, cortisol and testosterone changes build over 4–12 weeks.[9,1]
It works the same for everyone The biochemical cortisol drop is robust, but the pooled effect on subjective stress isn't always significant — the biggest responders are chronically stressed people with high baseline cortisol.[7,1]
More withanolides is always better Higher-concentration leaf-inclusive extracts carry more of the cytotoxic withanolides (withaferin A); the most-studied strength/testosterone extract (KSM-66) is deliberately standardised to negligible withaferin A.[15]
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Frequently asked questions

Is ashwagandha safe?

For most healthy adults, yes. A safety review of 30 human trials and a 12-month observational study in 191 people found adverse events mild and comparable to placebo, with no serious signal. The real cautions are specific: rare idiosyncratic liver injury, thyroid medication or hyperthyroidism, pregnancy, autoimmune disease, and combining it with sedatives.

Can ashwagandha damage your liver?

Rarely. There are documented cases of ashwagandha-associated liver injury in the literature — typically appearing 2–12 weeks after starting, usually reversible within 1–5 months of stopping. A 12-month observational study kept liver enzymes stable, and the severe or fatal cases occurred mostly in people with pre-existing chronic liver disease. Stop and see a doctor if you develop jaundice, dark urine, or itching, and avoid ashwagandha if you have liver disease.

Does ashwagandha affect the thyroid?

Yes — it can raise T3 and T4 and lower TSH. That is beneficial in subclinical hypothyroidism but a real reason for caution if you take thyroid medication or have an overactive thyroid, because the effect is additive. In people with normal thyroid function, trials show no meaningful change.

Is ashwagandha safe during pregnancy?

The honest answer: avoid it, as a precaution. The traditional claim that it is an abortifacient isn't actually backed by solid primary evidence (and animal developmental data are reassuring), but there are no adequate human pregnancy safety studies — so the standard recommendation is to avoid it while pregnant or breastfeeding.

Does ashwagandha make you sleepy?

It can cause mild drowsiness, especially at higher doses, because it acts partly through a GABA-ergic mechanism. That is why it is often taken in the evening — and why you should not combine it with sedatives, benzodiazepines, sleep medication, or alcohol without medical supervision, as the effects are additive.

Sources

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  2. Lopresti AL, Smith SJ, Malvi H, Kodgule R. An investigation into the stress-relieving and pharmacological actions of an ashwagandha (Withania somnifera) extract: a randomized, double-blind, placebo-controlled study. Medicine (Baltimore). 2019;98(37):e17186. PMID 31517876
  3. Lopresti AL, Drummond PD, Smith SJ. A randomized, double-blind, placebo-controlled, crossover study examining the hormonal and vitality effects of ashwagandha (Withania somnifera) in aging, overweight males. Am J Mens Health. 2019;13(2):1557988319835985. PMID 30854916
  4. 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
  5. 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(12):e6466. PMID 32021735
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  7. Albalawi AA, et al. Dual impact of Ashwagandha: significant cortisol reduction but no effects on perceived stress — a systematic review and meta-analysis. Nutr Health. 2025. PMID 40746175
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  10. Choudhary B, Shetty A, Langade DG. Efficacy of ashwagandha (Withania somnifera [L.] Dunal) in improving cardiorespiratory endurance in healthy athletic adults. Ayu. 2015;36(1):63–68. PMID 26730141
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  21. Ashwagandha. LiverTox: Clinical and Research Information on Drug-Induced Liver Injury. National Institute of Diabetes and Digestive and Kidney Diseases; 2023. Reference
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