Turmeric

What it is

Curcuminoids, mainly curcumin, come from the turmeric rhizome, and the body absorbs them poorly on their own [1]. Supplements come as standard extracts and as enhanced-absorption forms, such as micellar preparations, colloidal suspensions and products combined with piperine [1].

What the research says

Knee osteoarthritis pain has the most evidence. An analysis of 11 earlier meta-analyses found curcumin significantly lowered visual-analogue and WOMAC pain scores [2]. A 2021 meta-analysis of 16 trials (1,810 adults) found turmeric extracts reduced knee pain compared with placebo, with an effect of -0.82 and wide variation between trials [3]. Pain relief looks similar to NSAIDs: a 2021 review found similar effects [3], and a 2022 review found no significant difference from active treatments, including NSAIDs [4]. A 2026 combination trial containing 500 mg of curcumin found no pain difference from placebo over 12 weeks [5].

Across 66 randomised trials, turmeric or curcumin lowered CRP, TNF-α and IL-6, but IL-1β did not change [6]. In rheumatoid arthritis, six trials with 539 people found improved disease activity (DAS28) [7].

Doses used in studies

Arthritis trials used doses from 120 mg to 1,500 mg and lasted 4 to 36 weeks [8]. A knee osteoarthritis trial used 500 mg twice a day for 8 weeks [9], and another used 500 mg three times a day for 28 days against diclofenac [10]. The trials in one knee meta-analysis ran for up to 16 weeks [3].

Safety and interactions

Common side effects: turmeric extracts had 12% fewer adverse events than NSAIDs and similar rates to placebo in the trials pooled in one meta-analysis [3].

Upper limits: no upper intake limit was found in the studies read. Hepatotoxicity has been seen in a few rodent studies with high-dose turmeric rhizome powder or extract [11].

Liver injury: rare cases have been reported, mostly with high-dose, high-absorption products and often with other medicines [12]. Reported injury typically starts after one to four months and usually resolves on stopping the product, and acute liver failure has been reported rarely [11]. A 2026 case report describes recurrent autoimmune-like hepatitis after restarting a turmeric product with black pepper extract [13].

Interactions: piperine inhibits CYP3A4 and P-glycoprotein, which may raise toxicity from drugs including warfarin and carbamazepine [14]. The same review says curcumin changes how the body handles amlodipine [14]. No clinical trial of curcumin with warfarin was found.

Pregnancy and breastfeeding: no human safety trials of turmeric or curcumin supplements in pregnancy or breastfeeding were found. A 2026 review says pregnant women need more attention in interaction research [15].

People with liver problems: the US Pharmacopeia advises consulting a health-care practitioner before use if there is a history of liver problems [11].

Caveats and open questions

The knee meta-analyses cited here ran trials for up to 16 weeks, so longer effects are not well tested [3]. Results vary widely between studies [3]. Some trial authors have ties to companies that make the products tested [9][16]. Absorption studies are small, at 30 and 12 people [1][17]. Liver injury evidence is case reports, so the rate cannot be estimated [12].