Who Should Not Take Turmeric? Medicine by Medicine, in UK Names

Most people can take turmeric, and the spice in food is not the question. Turmeric and curcumin supplements are, for people on certain medicines and with certain conditions: anticoagulants and antiplatelets (curcumin reduces platelet clumping in the laboratory, though an uncontrolled human study found no change in INR or bleeding time over ten days), tamoxifen (a curcumin supplement lowered exposure to its active form by about 8%, not statistically significant, and by about 12% with black pepper extract), transplant medicines with a narrow window, and anyone with gallstones, bile-duct or liver disease, iron-deficiency anaemia, calcium-oxalate kidney stones or a pregnancy.^{1, 2, 3, 4} Three mechanisms sit behind the table: platelet effects in experimental systems (test-tube, animal or single-case data); piperine, the black pepper alkaloid in many turmeric products, which inhibits and can induce the liver enzyme CYP3A4 and the transporter P-glycoprotein that clear many medicines; and glucose-lowering in trials.^{5, 2, 6, 7, 8, 9, 10} Rows are about supplement doses, not cooking, and "what to do" is never "stop" or "change the dose": those decisions belong to the prescriber, so every row starts with your pharmacist.

Sources checked on 1 November 2026.

Which medications should not be taken with turmeric? Medicine by medicine

UK pharmacists' guidance advises against turmeric or curcumin during anti-cancer therapy, because curcumin may raise or lower the effect of several chemotherapy drugs; sulfasalazine levels were 3.2 times higher with 2 g of curcumin a day in a study of eight people; and about 7% of suspected reactions reported to the MHRA concern heart rate or rhythm.^{11, 14}

Which conditions mean you should not take turmeric supplements?

Gallstones, biliary disease and liver disease. Curcumin contracted the gallbladder by about 30% at 20 mg and 72% at 80 mg in two volunteer studies, so NHS Wales's medicines advice service advises avoiding turmeric and curcumin with gallstones, bile-duct obstruction, cholangitis, liver disease or any biliary disease.^{4, 15, 14} Liver injury from turmeric supplements is real, rare and idiosyncratic: in the US series of ten cases, eight were women, seven carried the immune gene variant HLA-B*35:01, which makes up about 6% of gene copies in the general population, three of seven products tested contained piperine, onset was one to four months and one person died; injury generally resolves on stopping.^{16, 17} In Tuscany all seven cases involved high-dose, high-absorption products, and trials have not reported liver toxicity.^{18, 17} Australia's medicines regulator, the Therapeutic Goods Administration, had received 18 reports of liver problems in people taking turmeric or curcumin products up to 29 June 2023; in four of them no other ingredient was likely to have contributed, and two of those four were severe, one fatal. It judged the risk rare, possibly higher with enhanced-absorption or higher-dose products, and not apparent with turmeric eaten in typical food amounts.¹⁹ The UK Committee on Toxicity concluded in December 2024 that there is reasonable evidence for a link, including in rare people below the acceptable daily intake, and that contamination was an unlikely cause.²⁰ Stop and see a GP the same day for dark urine, pale stools, yellow skin or eyes, nausea or abdominal pain; on methotrexate or other liver-processed medicines, or with fatty liver or primary biliary cholangitis, ask for liver tests.^{21, 17} See turmeric side effects and does turmeric change the colour of your urine.

Iron-deficiency anaemia. One man on about 3.2 g of turmeric extract a day became iron deficient and recovered two weeks after stopping; a 500 mg formulated curcumin dose with iron tablets did not reduce iron absorption in 155 adults.^{22, 23} If you take iron for anaemia, tell your GP you take turmeric.

Calcium-oxalate kidney stones. Turmeric powder's oxalate is 91% soluble and raised urinary oxalate in healthy adults, which the authors judged a stone risk in susceptible people.²⁴

Pregnancy, trying to conceive and breastfeeding. No human safety studies exist for turmeric supplements in pregnancy, only animal studies.^{25, 26} The spice is normal food, so turmeric milk made with powder from the jar is a food in the first trimester; a capsule is not. Allergy: itching and swelling are uncommon reported reactions to swallowed turmeric, and dermatitis and hives to turmeric on the skin; a reaction is a reason to stop.¹⁴ Is curcumin safe to take daily covers long-term use for everyone else.

Does the NHS recommend turmeric?

The NHS website has no turmeric page and neither recommends nor warns against it. The British Heart Foundation finds no strong evidence that turmeric supplements are good for your heart, warns that high doses could add to the effect of a blood thinner and raise the risk of a dangerous bleed, says people with liver or bile-duct problems should not take them, and advises asking your GP before taking any supplement.²⁷ The Welsh Medicines Advice Service, part of NHS Wales, publishes the most detailed UK guidance (October 2024), which most rows above draw on.^{11, 14} The Committee on Toxicity's December 2024 statement on liver injury is the UK expert committee's safety position.²⁰ A suspected reaction to a food supplement is reported to your local authority's food safety team, which works with the Food Standards Agency.²⁸ Doctors disagree because none of this is a guideline and there is no authorised health claim: readers describe a GP who did not know, a rheumatologist who allowed half a teaspoon, and a haematologist and a pharmacist who gave opposite answers on aspirin. Age does not set a dose: how much turmeric a day gives the teaspoon, the acceptable daily intake and the trial doses, and the Wellgard turmeric guide the trial evidence.

What we don't know

• Most interactions in people: the evidence for most rows is laboratory, animal or single-case data, and the tamoxifen study measured blood levels of the medicine, not cancer outcomes.^{11, 3}
• Anticoagulants: the ten-day study had no control group and did not test apixaban, rivaroxaban or edoxaban.¹
• Pregnancy: the studies are in animals only.²⁵

Frequently asked questions

Is turmeric a blood thinner?

Not in the sense a prescribed anticoagulant is; the phrase appears here only as a caution. Curcumin reduces platelet clumping in the laboratory; in the ten-day study bleeding time and INR did not change, and a normal INR does not prove the supplement is doing nothing, because INR measures the warfarin pathway, not platelets.^{1, 2} Turmeric cannot stand in for an anticoagulant, readers on warfarin or clopidogrel describe bruising, and no supplement amount has been shown safe with anticoagulants; the spice in food is fine. On the same NHS caution list: garlic, ginger, ginkgo, ginseng, willow, clove, angelica and danshen.¹¹

Can you take turmeric with blood pressure medication?

Ask the pharmacist, and never swap a blood pressure medication or tablet for turmeric. There is no interaction study with amlodipine, ramipril, losartan or bisoprolol; a pepper-extract product is the one to declare.^{11, 6}

Can you take turmeric with statins?

Tell your pharmacist. Rosuvastatin levels rose in animals given turmeric, and atorvastatin and simvastatin rely on CYP3A4, which piperine blocks; no human study.^{11, 6} Report unexplained muscle pain.

Should I stop turmeric before surgery, and does a curry count?

Stop supplements when the hospital says; the Welsh Medicines Advice Service advises stopping medicinal turmeric at least two weeks before elective surgery.¹⁴ A curry is food and does not count.

Does turmeric raise oestrogen, and can I take it with HRT or after breast cancer?

No human study shows curcumin raising oestrogen levels. In test tubes it displaces oestrogen from its receptor and has weak oestrogen-like actions, so UK pharmacists' guidance advises caution with HRT and with hormone-sensitive conditions such as breast cancer or endometriosis.^{11, 14} On tamoxifen, curcumin lowered exposure to the active metabolite, so ask the oncology team first.³

Sources

1. Hu S, et al. Interaction study between antiplatelet agents, anticoagulants, thyroid replacement therapy and a bioavailable formulation of curcumin. European Review for Medical and Pharmacological Sciences, 2018. Uncontrolled before-and-after study in patients on each medicine, 10 to 15 days; funding not stated on PubMed. PubMed 30070343.
2. Hussain Y, et al. Regulatory effects of curcumin on platelets: an update and future directions. Biomedicines, 2022. Narrative review of laboratory and animal studies; no conflicts declared. PubMed 36551934.
3. Hussaarts KGAM, et al. Impact of curcumin (with or without piperine) on the pharmacokinetics of tamoxifen. Cancers, 2019. Pharmacokinetic study in women with breast cancer; Dutch charitable foundation funding, no conflicts declared. PubMed 30909366.
4. Rasyid A, Lelo A. The effect of curcumin and placebo on human gall-bladder function: an ultrasound study. Alimentary Pharmacology and Therapeutics, 1999. Randomised double-blind crossover trial, 12 healthy volunteers, single dose; funding not stated on PubMed. PubMed 10102956.
5. Heck AM, et al. Potential interactions between alternative therapies and warfarin. American Journal of Health-System Pharmacy, 2000. Narrative review; funding not stated on PubMed. PubMed 10902065.
6. Bhardwaj RK, et al. Piperine, a major constituent of black pepper, inhibits human P-glycoprotein and CYP3A4. Journal of Pharmacology and Experimental Therapeutics, 2002. Laboratory study in human gut cells and liver microsomes; funding not stated on PubMed. PubMed 12130727.
7. Wang YM, et al. Piperine activates human pregnane X receptor to induce the expression of cytochrome P450 3A4 and multidrug resistance protein 1. Toxicology and Applied Pharmacology, 2013. Laboratory and mouse study; US National Institutes of Health funding. PubMed 23707768.
8. Hsieh YW, et al. Oral intake of curcumin markedly activated CYP 3A4: in vivo and ex-vivo studies. Scientific Reports, 2014. Rat and laboratory study; no competing interests declared. PubMed 25300360.
9. Bahari H, et al. Curcumin/turmeric supplementation on glycemic control in adults with prediabetes and type 2 diabetes: a systematic review and dose-response meta-analysis. Food Science and Nutrition, 2026. Meta-analysis, 34 trials; no conflicts declared, funding not stated on PubMed. PubMed 42005325.
10. Asher GN, et al. Common herbal dietary supplement-drug interactions. American Family Physician, 2017. Narrative review; funding not stated on PubMed. PubMed 28762712.
11. Welsh Medicines Advice Service (NHS Wales). Turmeric: potential interactions. Professional guidance, published 22 October 2024. wmic.wales.nhs.uk.
12. NHS. Taking methotrexate with other medicines and herbal supplements. Page last reviewed 14 March 2023 (review overdue). nhs.uk.
13. NHS. Polymyalgia rheumatica. Page last reviewed 23 April 2023 (review overdue). nhs.uk/conditions/polymyalgia-rheumatica.
14. Welsh Medicines Advice Service (NHS Wales). Turmeric: potential adverse effects. Professional guidance, published 22 October 2024. wmic.wales.nhs.uk.
15. Rasyid A, et al. Effect of different curcumin dosages on human gall bladder. Asia Pacific Journal of Clinical Nutrition, 2002. Randomised single-blind crossover trial, 12 healthy volunteers, single doses; funding not stated on PubMed. PubMed 12495265.
16. Halegoua-DeMarzio D, et al. Liver injury associated with turmeric, a growing problem: ten cases from the Drug-Induced Liver Injury Network. American Journal of Medicine, 2023. Case series, 10 people, US network cases 2004 to 2022; US National Institutes of Health funding. PubMed 36252717.
17. Akhtar N, et al. Rarely reported cases of hepatotoxicity associated with turmeric- and curcuminoid-containing dietary supplements: a comprehensive review by USP. Pharmaceutical Biology, 2026. Expert committee safety review (US Pharmacopeia); no conflicts declared. PubMed 42364655.
18. Lombardi N, et al. Acute liver injury following turmeric use in Tuscany: an analysis of the Italian Phytovigilance database and systematic review of case reports. British Journal of Clinical Pharmacology, 2021. Case analysis, 7 people, and systematic review of 23 published cases; funding not stated on PubMed. PubMed 32656820.
19. Therapeutic Goods Administration (Australia). Medicines containing turmeric or curcumin: risk of liver injury. Regulator alert (safety advisory), published 15 August 2023, covering reports received up to 29 June 2023. tga.gov.au.
20. Committee on Toxicity of Chemicals in Food, Consumer Products and the Environment. Statement on the potential risk to human health of turmeric and curcumin supplements (COT/2024/07), summary and conclusions, December 2024. Expert committee statement, including a 2021 survey of 15 UK supplements; read in the UK Government Web Archive, as the committee's own site has withdrawn the page. webarchive.nationalarchives.gov.uk.
21. NHS. Jaundice. Page last reviewed 22 January 2024. nhs.uk/conditions/jaundice.
22. Smith TJ, Ashar BH. Iron deficiency anemia due to high-dose turmeric. Cureus, 2019. Case report, 1 person; no competing interests declared. PubMed 30899609.
23. Lorinczova HT, et al. Acute administration of bioavailable curcumin alongside ferrous sulphate supplements does not impair iron absorption in healthy adults in a randomised trial. Nutrients, 2021. Randomised placebo-controlled trial, 155 adults, single dose; funded by the curcumin formulation's supplier. PubMed 34371810.
24. Tang M, Larson-Meyer DE, Liebman M. Effect of cinnamon and turmeric on urinary oxalate excretion, plasma lipids, and plasma glucose in healthy subjects. American Journal of Clinical Nutrition, 2008. Randomised crossover trial, 11 healthy adults, two 4-week periods; funding not stated on PubMed. PubMed 18469248.
25. Tossetta G, et al. The multifaced actions of curcumin in pregnancy outcome. Antioxidants, 2021. Narrative review; pregnancy studies in animals only; no conflicts declared. PubMed 33477354.
26. Soleimani V, Sahebkar A, Hosseinzadeh H. Turmeric (Curcuma longa) and its major constituent (curcumin) as nontoxic and safe substances: review. Phytotherapy Research, 2018. Narrative safety review; funding not stated on PubMed. PubMed 29480523.
27. British Heart Foundation. Should I be taking turmeric supplements? Heart Matters, answered by a BHF dietitian, page updated 22 August 2025. Charity guidance. bhf.org.uk.
28. Food Standards Agency. How to report a food safety or hygiene issue for members of the public. Official guidance, updated 5 August 2026. gov.uk.

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General information, not medical advice.