Red yeast rice

Is red yeast rice safe?

Not as a supplement, in our view. Red yeast rice is rice fermented with the mould Monascus purpureus. Depending on the strain and process, the mould makes monacolin K, which is chemically identical to the prescription statin lovastatin. If a product lowers your cholesterol, it is because you are taking a statin, at a dose nobody has checked.

That creates three problems. You get statin side effects and statin drug interactions with no prescriber watching. The dose can be anything from almost nothing to a meaningful drug dose. And the fermentation can produce citrinin, a kidney toxin. European regulators have concluded there is no safe intake, and member states voted in 2026 to ban it.

How much statin is in a capsule?

You cannot tell from the label. When researchers tested 28 red yeast rice brands from mainstream US retailers in 2017, none stated the monacolin K content. Two had none detectable. In the rest, the amount ranged from 0.09 to 5.48 mg per 1,200 mg of red yeast rice, a more than 60-fold spread, according to NCCIH, the US government's centre for complementary health.

For comparison, the lovastatin label gives a usual starting dose of 20 mg a day and a range of 10 to 80 mg. EFSA, the EU food safety authority, accepted in 2011 that 10 mg of monacolin K a day lowers LDL cholesterol. Some red yeast rice products have also been found to contain lovastatin added on purpose. In the US, the FDA says products with enhanced or added lovastatin cannot be sold as supplements and has sent warning letters to sellers.

What side effects does it cause?

The same as statins. EFSA's 2018 opinion reviewed case reports and found the most common targets were muscle (including rhabdomyolysis, a serious breakdown of muscle tissue), liver, nervous system, gut and skin. It judged 10 mg of monacolins a day to be of significant safety concern and found individual severe reactions, some needing hospital care, at intakes as low as 3 mg a day.

Industry submitted new data during a four-year EU review period. In its follow-up opinion published in early 2025, EFSA again could not identify any safe daily intake, including below 3 mg.

Contamination adds a separate risk. Citrinin is produced during fermentation and is toxic to the kidneys. In a 2021 study of 37 products, only one had citrinin below the EU maximum, and four products labelled "citrinin-free" were contaminated.

What happened in Japan in 2024?

In March 2024, Kobayashi Pharmaceutical recalled its beni-koji (red yeast rice) supplements after users developed kidney disease. Japan's health ministry linked the harm to puberulic acid, a contaminant found in products shipped from July 2023. By the end of June 2025, the company had received 413 reports of deaths; 141 concerned people who had taken the products, and the ministry was still assessing them case by case alongside more than 2,700 non-fatal reports.

The Kobayashi case was a manufacturing failure, not a monacolin effect. But it shows what can happen when a fermented product is made at scale with drug-like activity and food-level oversight.

Drug interactions

Because monacolin K is lovastatin, it carries lovastatin's interactions. The US label contraindicates lovastatin with strong CYP3A4CYP450 enzymesA family of liver enzymes that break down many medicines. When another drug or supplement speeds them up or slows them down, drug levels change.More in the glossary inhibitors: itraconazole, ketoconazole, posaconazole, voriconazole, clarithromycin, erythromycin, HIV protease inhibitors, nefazodone and cobicistat. It warns of higher muscle risk with cyclosporine, gemfibrozil and other fibrates, niacin at 1 g or more a day, danazol, diltiazem, verapamil, dronedarone and amiodarone, and with large amounts of grapefruit juice.

The biggest practical risk is doubling up. People who stop a prescribed statin such as atorvastatin or simvastatin because of muscle aches sometimes switch to red yeast rice, which can cause the same aches, or take both. Combining it with berberine, a common pairing in cholesterol blends, adds more interactions.

The rules in Europe and the US

• EU, 2022: Regulation 2022/860 limited monacolins to under 3 mg per daily portion and required the content on the label, plus warnings: not for pregnant or breastfeeding women, under 18s or over 70s, not with cholesterol-lowering medicines, and not with other red yeast rice products.
• EU, 2026: In March 2026 the Commission notified a draft to move monacolins to the list of prohibited substances. Member states approved it on 13 May 2026, with a 12-month transition for products already on the market expected once it is published.
• US: Legal as a supplement only if monacolin K is not added or enhanced, which in practice means the label tells you nothing about the dose.

If you are thinking of taking it

Talk to your doctor or pharmacist first, especially if you take any regular medicine, are pregnant or planning pregnancy, are over 70, or have liver, kidney or muscle problems. If statins caused side effects before, ask about another statin or a non-statin drug rather than an unmeasured one. Stop and seek help for unexplained muscle pain or weakness, dark urine, or yellow skin or eyes.

How we scored it

Regulatory actions (20) and quality (25) are the weakest factors: the EU is banning it, and products vary wildly and are often contaminated. Organ toxicity (35) and interactions (40) follow from its statin content. It scores below kava, which has a worse liver record but no statin-type interactions and no contamination problem on this scale.