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Turmeric and Curcumin: What the Trials Show, How the Forms Differ, and the Liver Risk

Turmeric and its main compound, curcumin, help a little in short trials: turmeric extracts eased knee arthritis pain (grade B), and curcumin slightly lowered blood sugar in adults with type 2 diabetes (grade B). Results for fatty liver, mood and weight are small or mixed. High-absorption products and black pepper extract (piperine) appear in rare but serious liver-injury cases, and piperine raises blood levels of some medicines.

Published How we grade evidenceEditorial policy

Turmeric is the ground root of the Curcuma longa plant; curcumin is its main yellow compound. Pure turmeric powder averaged 3.14% curcumin by weight in a test of 28 spice products (Tayyem 2006), so most trials used concentrated extracts, not the spice. Products vary in what they hold, and many add piperine from black pepper to raise absorption (NCCIH). This guide covers turmeric and curcumin taken by mouth.

The short version

  • Knee arthritis pain: less pain than placebo in short trials of adults with knee osteoarthritis, about matching anti-inflammatory pills (NSAIDs) in a few. Grade B (Wang 2021).
  • Blood sugar: slightly lower fasting glucose and HbA1c (a 3-month sugar average) than placebo in 18 trials of adults with type 2 diabetes. Grade B (Mokgalaboni 2024).
  • Fatty liver: some blood fats and sugar fell, but HbA1c, HDL cholesterol, CRP and TNF-alpha did not change in 21 trials of adults with fatty liver. Grade C (Ebrahimzadeh 2024).
  • Weight: about 0.6 kg more lost than in control groups across 50 trials of adults. Grade B for a very small effect (Unhapipatpong 2023).
  • Depression: lower scores in small trials of adults with depression, but the pooled result was fragile. Grade C (Musazadeh 2026).
  • Liver injury: rare but serious, including a death, often with high-absorption products or added black pepper extract. Grade C from case series (Halegoua-DeMarzio 2023; Lombardi 2021).
QuestionWhat trials foundSize of effectGrade
Knee arthritis pain (16 trials, 1,810 adults, against placebo or NSAIDs)Less pain than placebo; similar to NSAIDsStandardized mean difference -0.82 against placeboB
Blood sugar (18 trials, 1,382 adults with type 2 diabetes, against placebo)Lower fasting glucose and HbA1cAbout 11 mg/dL; 0.5 pointsB
Fatty liver (21 trials, 1,191 adults, against control groups)Some blood fats and sugar lower; HbA1c, HDL, CRP, TNF-alpha unchangedWeight 0.8 kg lowerC
Weight (50 trials of adults, against control groups)Slightly lower weight and waist0.59 kg; 1.3 cm of waistB
Depression (8 pooled trials, adults with depression, against placebo)Lower scores, but fragileStandardized mean difference -0.76C

Does turmeric help joint pain?

Grade B, for short-term knee pain. In 1,810 adults with knee osteoarthritis followed for up to 16 weeks across 16 trials, a 2021 review found turmeric extracts eased pain and improved function against placebo in 11 trials and matched NSAIDs in 5, with 12% fewer side effects than NSAIDs. Results varied widely, and people with a higher BMI gained less (Wang 2021). In 21 knee arthritis trials (1,705 patients), CRP and TNF-alpha, two blood markers of inflammation, fell, while ESR, IL-6 and PGE2 did not change (Hsueh 2025). To compare turmeric with glucosamine, boswellia and the rest, see supplements for joint pain.

Does curcumin lower blood sugar?

Grade B: a small drop in people with type 2 diabetes. Don't stop, skip or swap a diabetes medicine for it. Across 18 trials (1,382 adults with type 2 diabetes, average age 56), curcumin lowered fasting glucose by about 11.5 mg/dL and HbA1c by 0.54 percentage points against placebo, and CRP fell too; the trials used a mix of curcumin products, some absorption-enhanced (Mokgalaboni 2024). Curcumin may add to the blood-sugar lowering of diabetes medicines; if you take them, check your glucose and tell your prescriber. See supplements for blood sugar.

Does curcumin help fatty liver?

Grade C. In 21 trials of adults with non-alcoholic fatty liver disease (1,191 people; 50 to 3,000 mg a day of various curcumin products), curcumin lowered fasting glucose, insulin resistance, triglycerides, total and LDL cholesterol, and weight (0.81 kg) against control groups, but not HbA1c, HDL, blood pressure, CRP, TNF-alpha or waist size (Ebrahimzadeh 2024). Liver enzyme results disagree: in 15 trials (835 people) AST fell but ALT did not (Aragón-Vela 2024), while a summary of 11 meta-analyses found both fell, with HbA1c and HDL unchanged (Molani-Gol 2024). Our curcumin page shows fatty liver results as D (NAFLD) and B (MAFLD); we give C because the trials agree only on small metabolic changes and the liver enzyme results disagree. Weigh any gain against the liver-injury reports below and supplements and your liver.

Does curcumin help you lose weight?

Grade B, for a very small effect. Across 50 trials of adults, many with obesity or diabetes, curcumin lowered weight by 0.59 kg and waist size by 1.3 cm against control groups, with 21 of the trials rated at high risk of bias (Unhapipatpong 2023). In 20 trials of people with type 2 diabetes or prediabetes, weight fell 1.9 kg overall (low certainty) and 2.5 kg in prediabetes (moderate certainty), while BMI and waist-to-hip ratio did not change in type 2 diabetes (Moradi Baniasadi 2025); in 7 fatty-liver trials of a phytosome form, waist-to-hip ratio did not move (Liu 2024). Our curcumin page shows body fat as D, no effect, from fewer studies; the 50-trial analysis is the larger body of evidence for weight. See weight loss supplements.

Does curcumin help depression?

Grade C. Don't stop, skip or swap an antidepressant; changes go through your prescriber. A 2026 review of 19 trials of various curcumin products pooled 8 and found lower depression scores than placebo, but the trials disagreed a great deal and the result proved fragile in sensitivity checks (Musazadeh 2026). Another 2026 review of 26 trials (1,491 adults) found lower depression, anxiety and stress scores, with moderate to low certainty (Alsanie 2026). Our curcumin page shows grade B for depression; we give C, as our supplements and antidepressants guide does, because the pooled result was fragile. If you are thinking about suicide, call or text 988 (US) now.

Does curcumin help ulcerative colitis or Crohn's disease?

Grade C for ulcerative colitis, added to usual treatment. A 2025 review of 8 trials (482 people) found more clinical remission with curcumin on top of standard treatment (risk ratio 2.33), but no clear rise in remission seen at endoscopy; the trials varied widely and not all gave curcumin by mouth (Peng 2025). A review limited to curcumin by mouth (3 trials) found no clear benefit (Grammatikopoulou 2018).

Grade C for no benefit in Crohn's disease after surgery. In 62 people on azathioprine after bowel surgery, 3 g of curcumin a day for 6 months did not lower relapse (58% vs 68% on placebo), and severe relapse was more common (55% vs 26%) (Bommelaer 2020). Our curcumin page shows this as D; we give C because it was a randomized, placebo-controlled trial, though small and stopped early. Use curcumin only alongside, never instead of, what your gastroenterologist prescribes.

Which form absorbs best: black pepper, phytosome or micelles?

Grade C, for blood levels only. In healthy volunteers, 2 g of curcumin alone gave very low or undetectable blood levels; adding 20 mg of piperine raised absorption about 2,000% (Shoba 1998). In a crossover study of 30 healthy adults, micellar and dried colloidal forms delivered more curcuminoids per milligram than a standard extract, while a piperine combination did no better than the standard extract (Fança-Berthon 2021).

Blood levels are not health results: in the weight trials, enhanced forms lowered weight only slightly more (0.80 kg against 0.59 kg overall) (Unhapipatpong 2023). NCCIH warns these forms may harm the liver (NCCIH); all 7 Italian liver-injury cases involved them (Lombardi 2021).

Does black pepper extract change how medicines work?

Grade C: yes, for several medicines in small human studies. Piperine (20 mg) raised blood levels of propranolol (a heart and blood pressure drug) and theophylline (an asthma drug) in healthy volunteers (Bano 1991), of the seizure medicines phenytoin and carbamazepine in people with epilepsy (Pattanaik 2006; Pattanaik 2009), and of the HIV medicine nevirapine in 8 healthy men (Kasibhatta 2007). In lab tests it blocked P-glycoprotein and CYP3A4, two systems that clear many medicines (Bhardwaj 2002). On a prescription medicine, ask your pharmacist before using a product that lists piperine or black pepper extract.

Can turmeric damage your liver?

Grade C, from case series: rare but serious. A US network that tracks drug-related liver injury (DILIN) recorded 10 cases, every one since 2011: five people were admitted to hospital and one of them died. Symptoms appeared within 1 to 4 months of starting, 3 of the 7 products analysed also held piperine, and 7 people shared one immune gene type, HLA-B*35:01 (Halegoua-DeMarzio 2023). A woman who restarted the same turmeric and black pepper product 6 years after a first injury became sicker the second time (Patel 2026). LiverTox, the NIH liver-injury database, lists turmeric as a cause of acute liver injury (LiverTox), and in a national US survey turmeric was the most used of six liver-risk botanicals (Likhitsup 2024).

Can I take turmeric with blood thinners or other medicines?

Ask your prescriber or pharmacist first, and keep taking what you were prescribed.

  • Blood thinners and antiplatelet drugs (such as warfarin, apixaban, aspirin or clopidogrel): a 2022 review links turmeric to bleeding in people on anticoagulants (Hatfield 2022), and the INR clotting test rose in a patient on fluindione, a warfarin-type drug, in a probable interaction (Daveluy 2014). In one 10-day study of an absorption-enhanced curcumin without a comparison group, the INR held steady on warfarin or dabigatran and bleeding time on aspirin, ticlopidine or clopidogrel (Hu 2018). Stop turmeric or curcumin supplements 2 weeks before surgery or dental work, as that review advises for non-essential supplements (Hatfield 2022). Apixaban has not been tested; see can I take turmeric with Eliquis? and supplements and blood thinners.
  • Transplant medicines: a liver-transplant patient's tacrolimus level reached a toxic range, with kidney injury, after he ate large amounts of turmeric (Nayeri 2017). Tell your transplant team first.
  • Sulfasalazine (for colitis and arthritis): 2 g of curcumin raised its blood level 3.2-fold in 8 healthy volunteers (Kusuhara 2012).
  • Tamoxifen: in women with breast cancer, curcumin with piperine cut the drug's active form by 12% (Hussaarts 2019). During cancer care, ask your oncology team before any supplement.

What we'd skip

  • High-dose, high-absorption or piperine products if you take prescription medicines or have had liver trouble (Lombardi 2021; Bano 1991).
  • Curcumin to keep Crohn's disease away after surgery: no fewer relapses, more severe ones (Bommelaer 2020).
  • Curcumin supplements for weight loss: under 1 kg on average (Unhapipatpong 2023).
  • Loose turmeric powder of unknown origin: 14% of 356 samples from India, Pakistan, Sri Lanka and Nepal held detectable lead, some likely from lead chromate dye (Forsyth 2024).

Safety and interactions

  • Side effects: nausea, vomiting, acid reflux, stomach upset, diarrhea or constipation (NCCIH).
  • Amounts: no official upper limit has been set. NCCIH says turmeric or curcumin in conventional form, not modified to raise absorption, "is likely safe in the recommended amounts for up to 2 or 3 months" (NCCIH). For turmeric medicines, the European Medicines Agency's adult amounts include 0.5 to 1 g of powdered root 2 to 3 times a day (EMA). Ask your clinician before taking more than food amounts.
  • Diabetes medicines: curcumin may add to their blood-sugar lowering; check your glucose and tell your prescriber (Mokgalaboni 2024).
  • Gallbladder: 20 to 80 mg of curcumin made the gallbladder contract by about a third to nearly three-quarters within 2 hours in 12 healthy volunteers (Rasyid 2002). The European Medicines Agency advises against turmeric medicines with liver disease, gallstones, a blocked bile duct or other bile duct disease (EMA).
  • Kidney stones: supplement doses of turmeric raised urine oxalate, a stone risk factor, in 11 healthy adults (Tang 2008). With past stones or kidney disease, ask first; see supplements and your kidneys.
  • Iron: turmeric may bind iron in the gut; a 66-year-old man on turmeric extract developed iron-deficiency anaemia that cleared after he stopped (Smith 2019). With low iron or anaemia, ask your clinician first.
  • Pregnancy and breastfeeding: Turmeric supplements may be unsafe in pregnancy, and little is known about amounts above food while breastfeeding, NCCIH says (NCCIH). Ask your midwife or obstetric team before taking any.
  • Stacks: joint, liver and "inflammation" blends often repeat turmeric; check your stack.

When to see a doctor

  • Stop turmeric and talk to your clinician now (a liver blood test): jaundice (yellow skin or eyes), dark urine, nausea, poor appetite or unusual tiredness (NCCIH).
  • Urgent: bleeding that won't stop, black stools or blood in urine on a blood thinner or antiplatelet drug; severe pain under the right ribs or in one side of the back.
  • Soon: a bowel disease flare (more diarrhea, blood in stool, fever); low mood that is getting worse.
  • Before starting: liver or gallbladder disease, kidney stones, low iron, a transplant, a blood thinner or antiplatelet drug, diabetes medicines, seizure medicines, tamoxifen or other cancer treatment, pregnancy, or planned surgery or dental work.

Don't stop a prescribed medicine on your own; ask the prescriber or pharmacist. If you are under 18, ask a clinician.

FAQ

Is turmeric the same as curcumin? No. Turmeric is the whole spice; curcumin is its main active compound, about 3% of pure turmeric powder by weight. Most trials tested concentrated curcumin extracts.

Does black pepper make turmeric work better? It raises curcumin in the blood, about 2,000% in one small study, but that has not been shown to give better results. Piperine also raised blood levels of several medicines, and it was in 3 of the 7 products analysed from US liver-injury cases.

Is turmeric bad for your liver? Rarely, yes. US and Italian case series describe serious liver injury, including one death, often with high-absorption products. Stop it and get a liver test if you develop jaundice or dark urine.

How much turmeric should I take? No official upper limit exists. The European Medicines Agency's adult amounts for turmeric medicines include 0.5 to 1 g of powdered root 2 to 3 times a day; trials used various amounts for weeks to months. Ask your clinician before taking more than food amounts, especially of absorption-enhanced forms, which carry a liver warning.

What is the best time to take turmeric? No trial has compared morning and evening doses, so there is no evidence-based best time.

Can I take turmeric with blood thinners? Ask your prescriber first. Turmeric has been tied to bleeding in people on anticoagulants and to a higher INR in one case, though a 10-day study on warfarin or dabigatran found no INR change. Apixaban has not been tested. Stop it 2 weeks before surgery or dental work.

Sources

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