Who Should Not Take Ashwagandha? Liver, Thyroid and Medicines

Ashwagandha should not be taken by anyone pregnant or breastfeeding, by under-18s, by people with liver disease or heavy alcohol use, by anyone with a thyroid condition or on thyroid medicine, by people with autoimmune disease or on immunosuppressants, or alongside sedatives, and it is stopped before surgery. People on diabetes, blood-pressure, antidepressant or anticoagulant medicines ask a pharmacist first. The reasons are numbers, not alarm: about 25 published cases of liver injury, beginning typically 2 to 12 weeks after starting; thyroxine up across 23 pooled trials with TSH unchanged; and three case reports of thyrotoxicosis that resolved on stopping, set against 23 safety trials in 2,317 healthy adults whose liver, kidney and hormone markers stayed inside normal ranges.^{1, 2, 3, 4} Neither "100% safe" nor "dangerous" fits. Part of the Wellgard ashwagandha guide and the Wellgard sleep guide.

Who should not take ashwagandha?

• Pregnant or breastfeeding women: contraindicated by every regulator.
• Under-18s: no trials in children.
• Liver disease or heavy drinking: all three published liver deaths had existing cirrhosis.⁵
• Any thyroid condition, or levothyroxine or liothyronine: thyroxine rises; see below.
• Autoimmune disease, or methotrexate, biologics, ciclosporin or tacrolimus: immune-stimulating activity in laboratory work.
• Sedatives and anti-seizure medicines: additive drowsiness.
• Surgery: stop beforehand; tell the pre-operative team.
• Hormone-sensitive prostate cancer: testosterone rises in men (below).

What should you never mix with ashwagandha?

"Ask the pharmacist" never means "stop your medicine": that is the prescriber's decision.

Dispensing checks do not cover supplements, so bring the pack; ashwagandha vs lion's mane carries both sets of cautions.

Is ashwagandha bad for your liver?

Rarely, and recognisably. A review to December 2025 found 25 patients in 13 published reports: injury after weeks of use, usually cholestatic or mixed, with jaundice and itching; most recovered over weeks to months; one transplant; three deaths, all with existing cirrhosis.¹ In the first case series, five patients in Iceland and the US fell ill 2 to 12 weeks after starting; itching and jaundice lasted 5 to 20 weeks, and liver tests were normal within 1 to 5 months.⁶ Eight Indian cases confirmed the pattern, the three deaths among five patients with existing chronic liver disease.⁵ Against this, the 23 trials in 2,317 healthy adults kept liver tests normal to 180 days, as did an 80-person trial at 600 mg a day for 8 weeks; both screened out liver disease, so a rare reaction cannot be ruled out.^{4, 9} Dark urine, pale stools, itching, nausea or pain under the right ribs mean stop and see a GP; for yellow skin or eyes the NHS says to ask for an urgent GP appointment or call NHS 111.¹⁴

Is ashwagandha bad for kidneys?

Kidney markers stayed within normal ranges across the 23 safety trials in 2,317 healthy adults for up to 180 days, but none enrolled anyone with chronic kidney disease, on dialysis or with a transplant, so they cannot speak for those groups.⁴ One published case points the other way: a 69-year-old man with a kidney transplant developed acute rejection about two weeks after starting ashwagandha and lost the kidney; his doctors found no other trigger and advise warning transplant recipients.¹⁷ The NHS says not to take herbal medicines if you have kidney problems.¹⁵ So with kidney disease, dialysis or a transplant, ask the renal team first. The full kidney record is on the side effects of ashwagandha.

Is ashwagandha hard on your heart?

Cardiovascular markers stayed normal in the safety trials.⁴ Readers report palpitations and tremor; one published case has a mechanism: a 73-year-old woman's palpitations were a fast heart rhythm from thyrotoxicosis that settled when she stopped the supplement.³ New palpitations are a GP visit, with a thyroid test.

Does ashwagandha affect the thyroid?

In one direction: up. Pooled across 23 trials, thyroxine (T4) rose by 0.61 µg/dL while TSH and T3 did not change; in 50 people with subclinical hypothyroidism, 600 mg a day for 8 weeks lowered TSH and raised T4 against placebo; and three thyrotoxicosis case reports resolved on stopping.^{2, 3, 10} So anyone on levothyroxine or liothyronine, or with Hashimoto's, Graves' disease, a thyroid gland removed or treated with radioiodine, asks their GP first (see can I take ashwagandha with levothyroxine), and ashwagandha is never a replacement for thyroid medicine.

What are the side effects of ashwagandha?

In the trials: mild stomach upset, loose stools, nausea, headache and drowsiness, at rates similar to placebo.⁴ From users: vivid dreams, insomnia when taken late, feeling "wired" or shaky, the palpitations above and, in a minority, feeling flat, detached or unmotivated. One published case describes insomnia, a racing heart and anxiety after stopping 600 mg a day abruptly, the authors allowing that the underlying anxiety may have returned.⁷ Anyone who notices flatness stops, seeing a GP if it persists; anyone on antidepressants involves their prescriber (can you take sleep supplements with antidepressants); a suspected reaction can be reported through the MHRA Yellow Card scheme.¹¹ What ashwagandha does for the brain covers flatness; is ashwagandha safe to take daily covers how to stop.

What do UK and European regulators say?

Only one country prohibits it. Denmark could set no safe intake in 2020 and prohibits it in supplements; the Netherlands advised against its supplements and teas in March 2024; France (April 2024) and Germany (September 2024) said pregnant and breastfeeding women, under-18s and people with liver disease should not take it, France adding thyroid, androgen and heart disorders and sedatives; neither banned it. UK: the Food Standards Agency published its summary of 19 call-for-evidence responses on 25 June 2026; the Committee on Toxicity discussed its third draft statement on 8 September 2026 and will publish it shortly.^{12, 13} So: legal in UK supplements, neither prescribed nor recommended by the NHS, assessment imminent (position at 10 October 2026); the Wellgard ashwagandha guide carries the dated record in full.

Frequently asked questions

Can I take ashwagandha with magnesium, vitamin D or my other vitamins?

No interaction with magnesium, vitamin D or a multivitamin is reported in trials or case literature; the caution is additive drowsiness if the other product is a sleep blend.

Why don't doctors recommend ashwagandha?

Because it is a food supplement with no authorised health claim, no licensed use and small, short trials, and because of the interactions and liver cases above. A GP cannot prescribe it or vouch for a product.

Is ashwagandha safe for men, and does it increase testosterone?

For men without the conditions above, the trials raise no specific concern. Testosterone was about 57 ng/dL higher across 23 pooled trials; the trial that measured fatigue, vigour and sexual well-being alongside it found no difference from placebo.²

Is it safe to take ashwagandha while pregnant?

No: ashwagandha must not be taken in pregnancy or while breastfeeding, when the NHS says not to take herbal medicines.¹⁵ One open-label 12-week trial of 70 women in mid-pregnancy, on an extract its maker supplied, recorded no adverse events; it was small, unblinded and did not report birth outcomes, so the advice stands.¹⁶

Can ashwagandha cause kidney stones?

No published report links ashwagandha to kidney stones: a PubMed search on 17 October 2026 (ashwagandha and Withania somnifera with kidney stones, urolithiasis and oxalate) found no case report and no trial that measured stone risk, so there is no human evidence either way. The kidney markers the trials did measure, in healthy adults, stayed within normal ranges.⁴ Anyone who has had kidney stones falls under the NHS advice not to take herbal medicines with kidney problems, so the GP or renal team decides.¹⁵

Sources

1. McIntyre D, et al. Ashwagandha (Withania somnifera)-associated liver injury: a scoping review of clinical characteristics and safety considerations. Cureus, 2026. PubMed 42367407.
2. Fornalik M, et al. Hormonal modulation with Withania somnifera: systematic review and meta-analysis of randomized-controlled trials. Planta Medica, 2026. PubMed 41740946; Lopresti AL, et al. Hormonal and vitality effects of ashwagandha in aging, overweight males: a randomized, double-blind, placebo-controlled, crossover study. American Journal of Men's Health, 2019. PubMed 30854916.
3. Kamal HI, et al. Ashwagandha as a unique cause of thyrotoxicosis presenting with supraventricular tachycardia. Cureus, 2022. PubMed 35475098.
4. Coope OC, et al. Back to the roots: safety and tolerability of standardised ashwagandha (Withania somnifera) root extract in healthy adults, a systematic review of biomarkers and adverse events. Pharmaceuticals, 2026. PubMed 42198398.
5. Philips CA, et al. Ashwagandha-induced liver injury: a case series from India and literature review. Hepatology Communications, 2023. PubMed 37756041.
6. Björnsson HK, et al. Ashwagandha-induced liver injury: a case series from Iceland and the US Drug-Induced Liver Injury Network. Liver International, 2020. PubMed 31991029.
7. Holzman A, et al. Unmasking potential withdrawal effects of ashwagandha: a case report and review. Cureus, 2025. PubMed 40476122.
8. Farrin N, et al. The effects of ashwagandha (Withania somnifera) supplementation on fasting blood glucose and HbA1c: a systematic review and dose-response meta-analysis of randomized controlled trials. Diabetes Research and Clinical Practice, 2026. PubMed 42641800.
9. Verma N, et al. Safety of ashwagandha root extract: a randomized, placebo-controlled study in healthy volunteers. Complementary Therapies in Medicine, 2021. PubMed 33338583.
10. Sharma AK, Basu I, Singh S. Efficacy and safety of ashwagandha root extract in subclinical hypothyroid patients: a double-blind, randomized placebo-controlled trial. Journal of Alternative and Complementary Medicine, 2018. PubMed 28829155; van der Hooft CS, et al. Thyrotoxicosis following the use of ashwagandha. Nederlands Tijdschrift voor Geneeskunde, 2005. PubMed 16355578; Hayashi M, et al. Painless thyroiditis by Withania somnifera (ashwagandha). Cureus, 2024. PubMed 38559552.
11. MHRA Yellow Card scheme. yellowcard.mhra.gov.uk.
12. Food Standards Agency. Summary of responses to call for evidence on ashwagandha, 25 June 2026. gov.uk.
13. Committee on Toxicity. 8th September 2026 meeting: ashwagandha, third draft statement (TOX/2026/30). gov.uk.
14. NHS. Jaundice. nhs.uk.
15. NHS. Herbal medicines and complementary therapies. Page last reviewed 1 May 2026. nhs.uk.
16. Ajgaonkar A, et al. Frontiers in Global Women's Health, 2026. Extract supplied by its maker, no funding received. PubMed 41767760.
17. Sriperumbuduri S, et al. Ashwagandha and kidney transplant rejection. Kidney International Reports, 2020. Case report, one man. PubMed 33305135.