Red yeast rice is rice fermented with a mold, usually Monascus purpureus. Depending on the strain and the fermentation conditions, the mold can load the rice with compounds called monacolins. The main one, monacolin K, is structurally identical to the prescription statin lovastatin (NCCIH). It is sold mainly as a supplement for lowering cholesterol.
The most important fact: a red yeast rice product that lowers LDL cholesterol does so mainly because it contains a statin. In the US, FDA treats products with enhanced or added lovastatin as unapproved drugs, not dietary supplements (FDA warning letter, 2020). The EU caps monacolins at under 3 mg per daily portion (Regulation (EU) 2022/860). Products vary widely in strength, some contain the kidney toxin citrinin, and in 2024 contaminated red yeast rice tablets in Japan caused a large outbreak of kidney injury.
This page summarizes what clinical trials, product-testing studies and regulators report. It is for education only and is not medical advice.
| Property | Detail |
|---|---|
| What it is | Rice fermented with Monascus mold; sold as a food, traditional Chinese medicine and dietary supplement |
| Active compound | Monacolin K (lactone form identical to lovastatin), plus other monacolins |
| Route | Oral capsules or tablets |
| Doses used in key trials | 2.4 g/day of red yeast rice; 1,800 mg twice daily in statin-intolerant patients |
| Monacolin K in US products | 0.09–10.94 mg/day at label servings across 26 brands; not detected in 2 others |
| Half-life | Not established for red yeast rice products; human pharmacokinetic studies give conflicting results |
| US status | FDA: products with enhanced or added lovastatin cannot be sold as dietary supplements |
| EU status | Under 3 mg monacolins per daily portion, with mandatory warnings; under EU safety review |
| WADA status | Not named on the WADA 2026 Prohibited List |
What it is
Red yeast rice is technically “red mold rice”: M. purpureus is a mold rather than a yeast, but US supplement labels use the yeast name (NCCIH). In China it has traditionally been used as a food coloring and as a remedy for digestion and circulation (Regulation (EU) 2022/860).
Monacolin K works the same way as lovastatin because it is the same molecule. Lovastatin is an inactive lactone that the body converts to its β-hydroxyacid form. That acid blocks HMG-CoA reductase, the enzyme that controls an early, rate-limiting step in cholesterol production (lovastatin label). Less cholesterol made in the liver means lower LDL cholesterol in the blood. Red yeast rice also contains other monacolins, pigments and plant compounds, some of whose safety has not been evaluated (Regulation (EU) 2022/860).
How much monacolin K a product contains depends on the mold strain and how it was grown. Traditional red yeast rice contains trace amounts at most, while some commercial products contain large amounts. Some researchers have reported commercial lovastatin added to red yeast rice products (NCCIH).
| Comparison | Red yeast rice | Prescription lovastatin |
|---|---|---|
| Active statin | Monacolin K (= lovastatin), amount usually not on US labels | Lovastatin, labeled dose |
| Dose | Varies more than 120-fold between US brands | 10–80 mg/day; usual start 20 mg/day |
| Quality standard | Supplement manufacturing rules; content often differs from label | Pharmaceutical standards |
| Other contents | Other monacolins; possible citrinin | None |
Sources: Cohen et al., Eur J Prev Cardiol 2017; lovastatin label.
How it works in the body
Lovastatin is heavily removed by the liver on its first pass. Under 5% of an oral dose reaches the general circulation as active inhibitors, and exposure varies about 40% between people (lovastatin label). It is broken down by the liver enzyme CYP3A4, which is the basis of its main drug interactions (see below).
Whether monacolin K from red yeast rice behaves like a lovastatin tablet is unsettled:
- In a crossover study in 11 healthy volunteers, 20 mg of lovastatin gave much higher blood levels of lovastatin and its active acid than 2,400 mg of red yeast rice (Li et al., J Altern Complement Med 2005).
- A Taiwanese study found the opposite for one registered red yeast rice product: lovastatin dissolved faster, and blood levels of lovastatin and its active acid were higher than with lovastatin tablets. The authors linked this to lower crystallinity of the lovastatin in the rice (Chen et al., Int J Pharm 2013).
No study has set a half-life for red yeast rice products, and with doses varying so widely between brands, results from one product may not apply to another.
Regulatory status
United States
FDA’s position is set out in its warning letters. Traditional red yeast rice contains no more than trace amounts of lovastatin, if any. A product with “enhanced or added lovastatin” cannot be marketed as a dietary supplement. The reason is legal: the law excludes from the supplement definition any article first approved as a new drug, and FDA approved lovastatin (Mevacor) on August 31, 1987, before any lovastatin-rich red yeast rice was sold as a food or supplement. Courts upheld this position in a case over a product called Cholestin (Pharmanex v. Shalala, 10th Cir. 2000) (FDA warning letter, 2020).
That 2020 letter shows why this matters. FDA tested two samples of a product labeled as a supplement. One contained about 14.3 mg of lovastatin per capsule, or 85.8 mg/day at the maximum label dose, which is above the 80 mg/day maximum for prescription lovastatin. The other contained about 0.41 mg per capsule, or 2.48 mg/day (FDA warning letter, 2020). NIH’s complementary health center sums up the result: products with considerable monacolin K may lower cholesterol, but FDA considers them unapproved new drugs that are not sold legally in the US. For products with little monacolin K, it is unknown whether they work at all (NCCIH).
European Union
The EU path went from a health claim to a restriction:
| Year | Step |
|---|---|
| 2011 | EFSA accepted that monacolin K from red yeast rice helps maintain normal LDL cholesterol at 10 mg/day |
| 2018 | EFSA safety opinion: monacolins at 10 mg/day are of significant safety concern; severe reactions reported at intakes as low as 3 mg/day; no safe intake could be identified |
| 2022 | Regulation (EU) 2022/860: each daily portion must provide under 3 mg of monacolins; monacolins placed under EU scrutiny |
| 2025 | EFSA reviewed new industry data and again could not establish safety below 3 mg/day |
Sources: Regulation (EU) 2022/860; EFSA ANS Panel 2018; EFSA NDA Panel 2025.
The 2018 opinion found that supplement intake could expose people to monacolin K within the therapeutic range of lovastatin. The adverse-event profile matched lovastatin’s, led by muscle problems (including rhabdomyolysis, a severe breakdown of muscle tissue), then liver, nervous system, gut and skin. Cases of rhabdomyolysis, hepatitis and skin disorders needed hospital care (EFSA ANS Panel 2018; Regulation (EU) 2022/860).
The 2022 regulation, published June 2, 2022, also requires labels to state the monacolin content per portion and these warnings (Regulation (EU) 2022/860):
- not for pregnant or breastfeeding women, people under 18 or adults over 70;
- seek a doctor’s advice if health problems occur;
- not to be taken with cholesterol-lowering medicines;
- not to be taken with other red yeast rice products.
The regulation gave the Commission four years from its entry into force to decide whether to allow, restrict or ban monacolins in foods. In February 2025, EFSA concluded that the data submitted during the review did not establish safety below 3 mg/day and repeated that intakes as low as 3 mg/day could cause severe muscle and liver effects (EFSA NDA Panel 2025).
What the research shows
LDL cholesterol in randomized trials
| Trial | Design and population | Daily dose | Result |
|---|---|---|---|
| Heber et al., Am J Clin Nutr 1999 | Double-blind RCT, 83 US adults with high cholesterol, not on lipid drugs, 12 weeks, plus diet | 2.4 g red yeast rice | Total cholesterol fell from 254 to 208 mg/dL by week 8 (p under 0.001 vs placebo); LDL and triglycerides also fell; HDL unchanged |
| Becker et al., Ann Intern Med 2009 | RCT, 62 patients who had stopped statins because of muscle pain, 24 weeks, plus lifestyle program | 1,800 mg twice daily | LDL −43 mg/dL at week 12 and −35 mg/dL at week 24, vs −11 and −15 mg/dL on placebo; no difference in CK or pain scores |
The Becker trial is often cited for “statin-intolerant” patients. It was small, single-site and short, and it measured lab values rather than heart attacks or deaths (Becker et al., Ann Intern Med 2009).
Meta-analyses
A 2015 meta-analysis included only randomized trials of products with a known monacolin K content (20 studies). Red yeast rice lowered LDL by 1.02 mmol/L (≈39 mg/dL) versus placebo. The LDL drop did not differ from statin comparators (difference 0.03 mmol/L, 95% CI −0.36 to 0.41). The authors judged the quality of safety reporting low in most trials (Gerards et al., Atherosclerosis 2015).
| Outcome (Gerards 2015, 20 RCTs) | Result |
|---|---|
| LDL vs placebo | −1.02 mmol/L (95% CI −1.20 to −0.83) |
| LDL vs statin | No difference (0.03 mmol/L; 95% CI −0.36 to 0.41) |
| Liver and kidney injury | 0–5% of patients; risk not different from control |
The statin comparison is unsurprising: the products that lowered LDL contained a statin. For comparison with drugs that have outcome data and fixed doses, see atorvastatin, rosuvastatin and the non-statin ezetimibe.
Heart attacks and deaths
The only large outcome trial tested Xuezhikang, a partially purified red yeast rice extract, in China (Lu et al., Am J Cardiol 2008). Nearly 5,000 patients with a previous heart attack and average LDL levels were randomized to Xuezhikang or placebo for an average of 4.5 years.
| Outcome (China Coronary Secondary Prevention Study) | Placebo | Xuezhikang |
|---|---|---|
| Major coronary events (nonfatal heart attack or coronary death) | 10.4% | 5.7% (45% relative reduction) |
| Cardiovascular death | — | 30% lower |
| Total death | — | 33% lower |
A 2022 meta-analysis of 30 trials, mostly of Chinese red yeast rice preparations, reported lower mortality (RR 0.62, 95% CI 0.49–0.78) and fewer major cardiovascular events (RR 0.54, 95% CI 0.43–0.66). The authors noted heterogeneity and called for more high-quality studies (Yuan et al., Front Pharmacol 2022). These results come from standardized, pharmaceutical-grade extracts and do not show what an unstandardized supplement will do.
Quality and contamination
Monacolin content varies widely
Independent tests repeatedly find that the label does not tell the buyer how much statin is in the product:
| Study | Products tested | Main findings |
|---|---|---|
| Gordon et al., Arch Intern Med 2010 | 12 US products, all labeled “600 mg/capsule” | Monacolin K 0.10–10.09 mg per capsule; total monacolins 0.31–11.15 mg; 4 of 12 had elevated citrinin |
| Cohen et al., Eur J Prev Cardiol 2017 | 28 US brands from mainstream retailers | Monacolin K not detected in 2; in the rest, 0.09–5.48 mg per 1,200 mg of rice (over 60-fold range); 0.09–10.94 mg/day at label servings; no label gave the monacolin K amount |
| Righetti et al., Front Nutr 2021 | 37 EU products | Citrinin in all 37 (100–25,100 µg/kg); only 1 met the EU limit of 100 µg/kg; 4 labeled “citrinin free” were contaminated; monacolin K from 83% below to 266% above label; traces of simvastatin in 30 |
| Vanhee et al., Foods 2024 | 35 products sold online in the EU | At least 4 (≈11%) raised safety concerns from monacolin content over EU limits or bacterial contamination; 3 (≈9%) likely adulterated; 6 of 17 from one e-commerce platform had noncompliant labels |
The 2017 US study concluded that FDA’s supplement manufacturing standards had not made product strength predictable (Cohen et al., Eur J Prev Cardiol 2017).
Citrinin
Citrinin is a mycotoxin (mold toxin) that can be produced by Monascus and damages the kidneys (NCCIH). Gordon et al. described it as nephrotoxic in animals (Gordon et al., Arch Intern Med 2010). The EU maximum level for citrinin in red yeast rice supplements has been 100 µg/kg since April 2020 (Righetti et al., Front Nutr 2021).
The 2024 beni-koji kidney injury outbreak in Japan
In March 2024, kidney problems were publicized in Japan among people taking red yeast rice (beni-koji) tablets for cholesterol. The tablets (Beni-koji Choleste-Help) were made from Monascus pilosus; the tablets and fungal strains studied by investigators came from Kobayashi Pharmaceutical (Sekiguchi et al., Kidney Int Rep 2026). About 2,600 people received medical care and about 540 were hospitalized by the end of November 2024, and the Osaka City Government classified the event as food poisoning in October 2024 (Yoshinari et al., Proc Jpn Acad Ser B 2025).
The cause was not citrinin or monacolin K. The production strain could not make citrinin. Investigators instead found puberulic acid, an unexpected compound, in the implicated lots. A blue mold, Penicillium adametzioides, that makes puberulic acid was found in the factory, and it grew and produced puberulic acid on rice cultured with M. pilosus (Yoshinari et al., Proc Jpn Acad Ser B 2025). Puberulic acid damaged human kidney tubule cells in culture and caused kidney injury in mice, with RNA patterns similar to those of the toxic lots (Sekiguchi et al., Kidney Int Rep 2026). In a 28-day rat study, it damaged the proximal tubules at the top doses (10 mg/kg/day in males, 3 mg/kg/day in females); the no-observed-adverse-effect level was 1 mg/kg/day (Matsushita et al., J Toxicol Pathol 2025). These are animal and cell data.
A nationwide survey of Japanese nephrologists described 192 affected patients (Shinzawa et al., Kidney Int 2025):
| Finding | Result |
|---|---|
| Reduced kidney function at presentation (eGFR under 60 mL/min/1.73 m²) | 94.1% |
| Lab pattern | Fanconi syndrome (the kidney tubules leak potassium, phosphate, uric acid and glucose), with metabolic acidosis |
| Muscle breakdown as cause | No; creatine kinase was not raised |
| Biopsy | Tubulointerstitial nephritis in 50%, tubular necrosis in 32% |
| After stopping the product | Fanconi markers improved, but 87% still had eGFR under 60 at last follow-up |
Individual case reports show the same pattern, with full recovery in some patients and progression to chronic kidney disease in others (Habuka et al., BMC Nephrol 2024). The outbreak was a manufacturing contamination problem, not a property of red yeast rice in general, but it shows how little protection consumers have when a supplement is contaminated.
Side effects and risks
Statin-type side effects
Red yeast rice products with meaningful monacolin K can cause the same side effects as statins, including muscle, liver and kidney damage, plus digestive complaints such as diarrhea, nausea and stomach pain (NCCIH). The lovastatin label lists:
- Muscle: myopathy and rhabdomyolysis, with risk raised by high blood levels of the drug and by interacting medicines, and rare immune-mediated necrotizing myopathy.
- Liver: persistent transaminase rises over 3 times the upper limit of normal in 1.9% of adults in early trials; in the 48-week EXCEL trial, 0.1% on placebo or 20 mg/day vs 1.5% on 80 mg/day.
Source: lovastatin label.
What the trials and the regulators say
The two main sources disagree, partly because they look at different evidence:
- A 2019 meta-analysis of 53 randomized trials (8,535 people) found no increase in muscle problems (OR 0.94, 95% CI 0.53–1.65) and fewer non-muscle and serious adverse events than control (Fogacci et al., Pharmacol Res 2019).
- EFSA’s 2018 and 2025 opinions relied on case reports and surveillance data and found severe reactions at 3 mg/day. EFSA noted that small trials not designed to detect rare harms cannot cancel out case reports for a compound identical to lovastatin (EFSA ANS Panel 2018; Regulation (EU) 2022/860; EFSA NDA Panel 2025).
Interactions
Because monacolin K is lovastatin, red yeast rice can have the same drug interactions as statins (NCCIH). The lovastatin label sets these rules (lovastatin label):
| Interacting agent | Label recommendation for lovastatin |
|---|---|
| Strong CYP3A4 inhibitors (itraconazole, ketoconazole, posaconazole, voriconazole, clarithromycin, erythromycin, telithromycin, HIV protease inhibitors, nefazodone, cobicistat products) | Contraindicated |
| Gemfibrozil, cyclosporine | Avoid |
| Danazol, diltiazem, dronedarone, verapamil | Do not exceed 20 mg/day |
| Amiodarone | Do not exceed 40 mg/day |
| Grapefruit juice | Avoid; large amounts of double-strength juice raised lovastatin exposure about 15-fold |
With a supplement, the monacolin K dose is usually unknown, so these limits cannot be applied reliably. Taking red yeast rice with a prescription statin doubles up the same drug class; EU labels must warn against using it with cholesterol-lowering medicines (Regulation (EU) 2022/860). Red yeast rice is also sold in multi-ingredient products, for example combined with berberine and policosanol (Millán et al., Clin Investig Arterioscler 2016). EFSA noted that the components of such products have not been fully evaluated alone or in combination (Regulation (EU) 2022/860). Berberine has its own documented effects on drug-metabolizing enzymes.
Who should not use it
- Pregnancy and breastfeeding: no safety studies exist, and red yeast rice is not recommended (NCCIH). The lovastatin label lists pregnancy and nursing as contraindications (lovastatin label).
- Liver disease: active liver disease or unexplained persistent transaminase rises are contraindications for lovastatin (lovastatin label).
- Groups named on EU labels: children and adolescents under 18 and adults over 70 (Regulation (EU) 2022/860).
Key takeaways
- It works because it contains a statin. Monacolin K is identical to lovastatin, and products that lower LDL do so through the same enzyme.
- LDL drops are real in trials. Products with known monacolin K content lowered LDL by about 39 mg/dL versus placebo, and one large Chinese trial of a standardized extract cut coronary events.
- The dose on the shelf is unpredictable. Tests found monacolin K ranging more than 120-fold between US brands, with none listing the amount.
- Regulators restrict it. FDA treats lovastatin-rich products as unapproved drugs; the EU caps monacolins under 3 mg per daily portion, and EFSA has not found any safe intake.
- Contamination is a documented risk. Citrinin is common in tested products, and puberulic acid contamination caused the 2024 kidney injury outbreak in Japan.
- Statin interactions apply. Strong CYP3A4 inhibitors, gemfibrozil, cyclosporine and grapefruit juice interact with lovastatin, and combining red yeast rice with a prescription statin adds more of the same drug class.
Sources
- National Center for Complementary and Integrative Health. Red Yeast Rice: What You Need To Know. Updated November 2022. NCCIH.
- Food and Drug Administration. Warning letter to Dr. Sam Robbins, Inc. dba HFL Solutions, LLC (MARCS-CMS 608729). August 28, 2020. FDA.
- Lupin Pharmaceuticals. Lovastatin tablets USP prescribing information, 2026. DailyMed.
- European Commission. Commission Regulation (EU) 2022/860 of 1 June 2022 amending Annex III to Regulation (EC) No 1925/2006 as regards monacolins from red yeast rice. Official Journal of the European Union. 2022;L 151:37. EUR-Lex.
- EFSA Panel on Food Additives and Nutrient Sources added to Food (ANS), Younes M, Aggett P, Aguilar F, et al. Scientific opinion on the safety of monacolins in red yeast rice. EFSA Journal. 2018;16(8):5368. DOI.
- EFSA Panel on Nutrition, Novel Foods and Food Allergens (NDA), Turck D, Bohn T, Cámara M, et al. Scientific Opinion on additional scientific data related to the safety of monacolins from red yeast rice submitted pursuant to Article 8(4) of Regulation (EC) No 1925/2006. EFSA Journal. 2025;23(2):9276. DOI.
- Heber D, Yip I, Ashley JM, et al. Cholesterol-lowering effects of a proprietary Chinese red-yeast-rice dietary supplement. Am J Clin Nutr. 1999;69(2):231–236. PubMed.
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- Yuan R, Yuan Y, Wang L, et al. Red yeast rice preparations reduce mortality, major cardiovascular adverse events, and risk factors for metabolic syndrome: a systematic review and meta-analysis. Front Pharmacol. 2022;13:744928. PubMed.
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- Shinzawa M, Matsui I, Doi Y, et al. A nationwide questionnaire study evaluated kidney injury associated with Beni-koji tablets in Japan. Kidney Int. 2025;107(3):530–540. PubMed.
- Habuka M, Hosojima M, Yata Y, et al. Fanconi syndrome with acute proximal tubular injury induced by a dietary supplement containing beni-koji: a case series report. BMC Nephrol. 2024;25(1):446. PubMed.
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- Matsushita K, Tsuji G, Akane H, et al. A 28-day subacute toxicity study of puberulic acid in Crl:CD(SD) rats. J Toxicol Pathol. 2025;38(4):223–236. PubMed.
- Millán J, Cicero AF, Torres F, et al. Effects of a nutraceutical combination containing berberine (BRB), policosanol, and red yeast rice (RYR), on lipid profile in hypercholesterolemic patients: a meta-analysis of randomised controlled trials. Clin Investig Arterioscler. 2016;28(4):178–187. PubMed.
- World Anti-Doping Agency. 2026 Prohibited List. WADA.