Turmeric rhizome (Curcuma longa)

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15. Safety

15.1 Overall position

Read this first. Turmeric and curcumin in medicinal dosage forms carry a rare risk of liver injury that the TGA has investigated and acted on. Among the Australian reports were two severe cases with no other likely contributing ingredient, one of them fatal, and the risk appears higher with bioavailability-enhanced products and at higher doses. It is set out in 15.3. Any oral Australian listed medicine with this ingredient as an active must carry the CURC liver warning on its label, and the ingredient is barred below two years of age [9,24]. Concentrated preparations may also raise INR in someone on warfarin or another vitamin K antagonist, at turmeric intakes of a few grams a day (15.6). Everything after this paragraph is read against those two facts.

At dietary and traditional doses of the whole rhizome, turmeric is a well-tolerated drug with a long record of use. Mills and Bone’s summary assessment is that no adverse effects from ingestion are expected within the recommended dosage [6]. Numerous clinical trials of turmeric and curcuminoid products have reported no organ toxicity and no serious adverse events [19]. The TGA’s own position is that the risk of liver injury does not appear to relate to turmeric consumed in typical dietary amounts as a food [24].

Two things have changed that picture at the concentrated-extract end, and both are recent enough that older textbook entries do not carry them: the liver-injury signal, and the regulatory response to it.

15.2 Adverse effects from trials

In the knee-osteoarthritis network, gastrointestinal symptoms were the commonest adverse event, at 6.54 per cent with bioavailability-enhanced preparations and 6.06 per cent with polysaccharide preparations; the polysaccharide group had the highest overall adverse-event rate at 30.30 per cent, most of it miscellaneous symptoms. The events were mild and none led to serious consequences, and the authors note that inconsistent adverse-event definitions across trials limit how far the numbers can be trusted [14].

The EMA monograph lists mild dry mouth, flatulence and gastric irritation, frequency not known [8]; in one irritable-bowel trial cited in its assessment report, about a quarter of patients reported dry mouth and flatulence [8]. In the one formal non-inferiority trial against ibuprofen, abdominal pain or discomfort was less frequent on the turmeric extract than on ibuprofen (p = 0.046), and one extract patient against seven ibuprofen patients withdrew because of adverse events [41]. Other reported effects: frequent bowel movements and mild gastric discomfort, particularly at the high curcumin doses used in recent trials; two of 19 patients on 2,500 mg/day of curcumin reported gastric irritation; mild nausea, diarrhoea, headache, tiredness and sleepiness in the turmeric arm of Thamlikitkul 1989, at similar rates to placebo; localised itchiness after topical application; scalp itching in 1 of 62 patients in an 18-month study of topical curcumin [6,8]. Phase I dose-escalation studies of curcuminoids found single oral doses up to 12 g/day tolerated [6]. Turmeric oil at 1.8 and 3 mL/day for one and two months caused no toxic effects in nine healthy volunteers apart from one allergic reaction [6].

Allergic contact dermatitis is reported but rare; a 2001 review of the literature concluded that allergic reactions to turmeric are rare, and patch-test reactions occurred mainly in people regularly exposed or with existing fingertip dermatitis [5,6].

One finding with a practical edge: eleven healthy volunteers who took turmeric rhizome for four weeks, providing 55 mg/day of oxalate, had significantly higher urinary oxalate than a cinnamon comparison and a control, which may raise kidney-stone risk [6].

Hair loss occurred in rats fed turmeric at 10 per cent of the diet, and Mills and Bone note that turmeric has traditional use as a topical depilatory, so they advise care in patients complaining of hair loss [6].

15.3 Liver injury: what is known, and what Australia did about it

This is the material change in the drug’s safety profile since the standard textbooks were written.

The Australian signal. The TGA published a safety alert on 15/08/2023. It had received 18 reports of liver problems in consumers taking products containing Curcuma longa or curcumin up to 29/06/2023. Nine of those had enough information to suggest liver injury that may have been caused by the product. Of those nine, four involved no other ingredient likely to have contributed. Two of the four were severe, including one with a fatal outcome. The remaining five involved products with other potentially hepatotoxic ingredients. The TGA completed a safety investigation and concluded there is a rare risk of liver injury from C. longa and curcumin in medicinal dosage forms; that the risk may be higher for products with enhanced absorption or bioavailability and at higher doses; and that people with existing or previous liver problems may be more likely to be affected. The alert notes there are over 600 listed medicines in the ARTG containing these Curcuma species or curcumin [24].

The regulatory response. The proposed label warning and dose restrictions were consulted on and the final changes commenced 01/03/2024, with a twelve-month transition ending 01/03/2025. In the instrument now in force, item 1647 CURCUMA LONGA requires, on any oral medicine using it as an active, the label statement quoted in full in the identity card, and caps the daily curcumin dose at 36 mg (2–3 years), 48 mg (4–11 years) and 123 mg (12–17 years), with the ingredient not permitted below 2 years of age. Items 1646 C. aromatica, 1648 C. zanthorrhiza, 1649 C. zedoaria and 1650 CURCUMIN carry the same requirements; item 1650 also restricts curcumin’s excipient use to a colour in topical and oral medicines [9].

The international picture, which is consistent. Italy introduced mandatory label warnings on Curcuma food supplements in 2019 and strengthened them in 2022. ANSES in France reported more than 100 nutrivigilance reports including hepatitis and recommended keeping supplement-derived curcumin below 153 mg/day for a 60 kg adult, with particular concern for bioavailability-enhanced formulations. Health Canada has updated its monograph for concentrated turmeric extracts and curcuminoids: extracts standardised to 75 per cent curcuminoids or more are not to exceed 1,500 mg of curcuminoids a day (500 mg a single dose), absorption-enhanced forms fall outside the monograph and need their own evidence, and liver cautions and stop-use advice are required (an overseas position, not Australian law). The NIH LiverTox database now scores turmeric’s likelihood of causing clinically apparent liver injury as ‘A’, its highest category, meaning a well-documented cause. In 2026 the United States Pharmacopeia’s Dietary Supplement Admission Evaluation and Labeling Expert Committee recommended adding a liver caution to the USP turmeric and curcuminoid monographs, advising users to stop the product and seek advice if abdominal pain, dark urine or jaundice appear [19].

The clinical picture of the injury. Predominantly hepatocellular, with ALT and AST often above 1,000 U/L; histology ranging from acute hepatitis and interface hepatitis to autoimmune-like features and cholestasis, with some cases meeting criteria for drug-induced autoimmune hepatitis. Typical latency one to four months. Most cases resolve within one to three months of stopping, and positive rechallenge has confirmed causality in several. Acute liver failure requiring transplantation has occurred, rarely. The proposed mechanism is idiosyncratic and immune-mediated, and a strong genetic association with the HLA-B*35:01 allele has emerged. Piperine, included to enhance curcumin absorption, was implicated in many of the reported cases [19].

What the case literature does not show. Published case reports often involve concomitant medicines or supplements, product analysis is usually absent, and rodent toxicology shows hepatotoxicity only at high doses [19]. Contamination has been considered as an explanation and judged unlikely in UK surveys [19]. So this is a rare idiosyncratic reaction in susceptible people rather than a dose-dependent toxicity in everyone, and the evidence suggests genetic susceptibility rather than establishing it.

The Australian pharmacovigilance count. Akhtar and colleagues searched the TGA’s Database of Adverse Event Notifications for "curcumin" and report 100 adverse-event reports for 01/01/1971 to 15/09/2025, including events related to turmeric, with gastrointestinal effects most frequent and diarrhoea the commonest single event [19]. That count is theirs, from their own query, and is reported as such. Two further figures from the same query belong beside it. Of that curcumin set, at least ten reports were liver-related: jaundice in four, abnormal liver function tests in three, hepatomegaly in one, and acute hepatic failure and cholestatic hepatitis in one each, the acute hepatic failure in a male patient with a fatal outcome. A separate DAEN search on ‘Curcuma longa’ returned 332 reports, 274 of them attached to a single suspected medicine, including one death; products appearing under both terms are counted in both sets [19].

AIP’s own checks on the Australian material, 27/09/2026. The TGA safety alert page was opened and read in full at Medicine review, and again unchanged in October 2026 and October 2026, and every figure quoted above was taken from it directly: 18 reports to 29 June 2023, nine with enough information, four with no other contributing ingredient, two of those severe including one fatal, the remaining five with other potentially hepatotoxic ingredients, and over 600 listed medicines in the ARTG [24]. Item 1647 of the Permissible Ingredients Determination was read in the authorised text of F2026L00707 the same day, and the CURC statement and the three paediatric caps quoted in this monograph are verbatim from it [9]. Note what the Determination does not do: there is no adult curcumin cap in Australian law. The caps at 36, 48 and 123 mg a day apply to children only.

The DAEN was attempted by AIP and could not be queried. The Database of Adverse Event Notifications is served as a Power Apps portal whose data endpoints answer HTTP 301 to anything without a live browser session, and no request AIP made on 27/09/2026 returned data. AIP therefore states no DAEN count of its own, and the figure above stays attributed to Akhtar and colleagues. A DAEN query run by a person with a browser belongs in version 1.1.

15.4 Toxicology

LD₅₀ values recorded by Mills and Bone, all indicating low acute toxicity: turmeric petroleum ether extract, oral, rats, 12.2 g/kg; turmeric oleoresin, oral, mice and rats, > 10 g/kg; turmeric oil, oral, rats, > 5 g/kg; turmeric essential oil, dermal, rabbits, > 5 g/kg [6].

No toxic effects were seen with turmeric powder at 2.5 g/kg or 30 per cent of the diet, ethanol extract at 0.3 to 3 g/kg, or curcumin at 1 to 5 g/kg given orally to mice, rats, guinea pigs and monkeys; nor in chronic studies of turmeric powder at 0.1 to 10 per cent of the diet and 500 mg/kg/day for up to 52 weeks, a hydroalcoholic extract at 4 mg/kg/day for 4 weeks, a petroleum-ether extract at 1 and 2 g/kg for 4 weeks, or curcumin at 0.1 to 2 per cent of the diet or 400 to 800 mg/kg for 8 to 13 weeks [6].

Against that: turmeric extract at 0.05 to 0.25 per cent of the diet and turmeric powder at 0.2 to 5 per cent caused some hepatotoxicity in mice fed for 14 days or longer, and the mouse is probably a susceptible species for turmeric-induced toxicity [6]. Pigs fed turmeric oleoresin at 296 and 1,551 mg/kg/day for 102 to 109 days showed thyroid enlargement, pericholangitis and epithelial changes in kidney and bladder [6]. Rats fed turmeric at 10 per cent of the diet gained less weight: over 8 weeks in one study, put down to lower food intake from the changed taste, and over 4 to 7 weeks in another, with hair loss and no apparent fall in food intake [6]. The USP review adds that repeat-dose studies established NOAELs at the highest doses tested, 1,000 to 2,000 mg/kg bw/day, with isolated reversible findings of gastric erosion at 100 mg/kg bw/day and mild fatty degeneration of the liver at 250 mg/kg bw/day [19]. JECFA set an acceptable daily intake for curcumin of 0 to 3 mg/kg bw, later supported by EFSA [19].

Mutagenicity: turmeric powder, ethanol extract, oleoresin and curcumin were not mutagenic in the Ames test, and turmeric powder and curcumin were not mutagenic in vivo after oral administration; one study found a turmeric ethanol extract mutagenic in the Ames test where another did not; a methanol extract caused chromosomal damage in mice after intraperitoneal administration at about 6 g/kg [5,6]. The WHO monograph’s summary is that the drug is not mutagenic in vitro [5].

15.5 Contraindications

15.6 Interactions

The EMA’s monograph states "none reported" for interactions [8], which reflects the traditional-use dossier rather than the wider literature and should not be read as an all-clear.

15.7 Pregnancy, lactation, children and older people

Pregnancy. Mills and Bone assign Category A — no proven increase in malformation or other harmful effects despite consumption by a large number of women as an item of diet — and note that turmeric decoction is traditionally used in Ayurveda for vomiting of pregnancy and that Indonesian and Fijian traditions give it at parturition [6]. Against that: turmeric extract at 100 and 200 mg/kg/day given orally to mice during the first week of pregnancy reduced implantations and pups delivered at term, though without teratogenic effect; very high doses (15 g/kg) of other Curcuma species used in TCM prevented implantation or caused abortion in mice; and turmeric decoction and extract stimulated isolated uteri of mice and guinea pigs and uterine fistulae in rabbits [6]. No reproductive toxicity or teratogenicity was seen in rats fed turmeric at 50 mg/kg/day for 52 weeks or in rats and rabbits fed curcumin at 600 and 1,600 mg/kg/day from days 6 to 15 post-coitus [6]. Orally administered turmeric was not teratogenic in mice or rats [5]. The EMA’s position is different and more cautious: safety in pregnancy and lactation has not been established and use is not recommended in the absence of sufficient data [8]. WHO says the same of pregnancy and advises against use as a precaution [5]. The honest reading is that dietary quantities carry a long and reassuring human record and concentrated extracts do not, and the EMA is speaking about medicinal products while Mills and Bone are speaking about the food. Grade: long human dietary exposure without a recorded signal, which is observational and uncontrolled; no human data at all for concentrated extracts; animal data mixed and at high doses (Tier P).

Lactation. Mills and Bone consider turmeric compatible with breastfeeding, and note the Fijian use to promote lactation [6]. WHO says excretion into breast milk and effects on the newborn have not been established and advises against use during lactation except on qualified advice [5]. The EMA does not recommend use [8]. Grade: no human data on transfer to milk or effects on the infant; the textbook position rests on dietary and traditional use.

Fertility. Care is advised in women wishing to conceive, on the implantation data above [6]. Subcutaneous injection of an alcohol extract into immature male rats for 10 days decreased testis weight and testosterone; a 90-day oral study of a concentrated ethanolic extract at 100 mg/kg/day in mice increased sperm motility and organ weights and decreased red and white cell counts, without spermatotoxic effect [6].

Children. Not permitted below 2 years in an Australian listed medicine; curcumin capped at 36, 48 and 123 mg/day for the three paediatric bands [9]. The EMA does not recommend use under 18 [8]. Mills and Bone say no information is available but adverse effects are not expected [6]; WHO says safety and effectiveness in children have not been established [5]. Grade: Australian law, plus an absence of paediatric trial data.

Older people. No specific data. The EMA’s posology makes no distinction between adults and the elderly [8].

15.8 Overdose and phototoxicity

No incidents of overdose found in the published literature [6]. Single oral doses of curcuminoids up to 12 g/day were tolerated in phase I studies [6]. Patients applying turmeric or curcumin topically should avoid excessive sun exposure, because curcumin is phototoxic in vitro [6].

15.9 Practical safety summary for dispensing

1. Whole dried rhizome at 1 to 4 g/day is the form and the dose with the deepest safety record.
2. A concentrated curcuminoid extract, particularly one with piperine or another absorption enhancer, is a different risk proposition, and that is the form the liver-injury cases cluster around.
3. Ask about liver disease, past or present, before dispensing either, and do not dispense to someone with it.
4. Ask about biliary obstruction and gallstones.
5. Ask about warfarin and other vitamin K antagonists, about antiplatelet medicines, and about tacrolimus or another calcineurin inhibitor. If a vitamin K antagonist is in use, treat turmeric at any medicinal dose as an interaction worth monitoring INR for: the published cases sit at a few grams a day, not at the 15 g/day Mills and Bone name.
6. Review at four to six weeks rather than repeating indefinitely; the reported latency to liver injury is one to four months.
7. Tell the person what to watch for, in the TGA’s own terms: yellowing of the skin or eyes, dark urine, nausea, vomiting, unusual tiredness, weakness, stomach or abdominal pain, loss of appetite, and the itching the CURC label statement adds. Tell them to stop the product immediately and seek medical advice if any appear, which is the TGA’s own instruction [9,24]. AIP adds liver function tests the same week, and same-day medical assessment for jaundice or dark urine. Jaundice with confusion, drowsiness, or easy bleeding or bruising can mean acute liver failure, which is an emergency: call 000.
8. Buy from a supplier who can show a certificate of analysis with a curcuminoid profile, and treat a relative curcumin content above about 85 per cent of total curcuminoids as a reason to ask questions.

Where a referral is needed: consult a degree-qualified herbalist with competencies and adequate training in pharmacognosy.