The Side Effects of Red Yeast Rice

Red yeast rice capsules and tablets

Verywell / Anastasia Tretiak

Red yeast rice (RYR) is a dietary supplement often used to lower cholesterol, and it has been proven effective in some people. But it's also known for its side effects, so if you're considering taking red yeast rice, it's important to learn about the side effects before you start.

This article looks at the health benefits of RYR, its side effects, possible reasons why you shouldn't take it, and why it's important to first talk with your healthcare provider.

What Is Red Yeast Rice?

Long used in traditional Chinese medicine, RYR is produced by fermenting a type of red yeast called Monascus purpureus on white rice. It contains a group of substances called monacolins, which includes monacolin K.

Lovastatin is the active ingredient in a number of prescription drugs used to treat high cholesterol, including Mevacor and Altoprev. Monacolin K is chemically identical to the lovastatin in these drugs, so it is sometimes called "natural lovastatin."

In 2007, the Food and Drug Administration (FDA) banned red yeast rice products containing natural lovastatin, which "may contain an unauthorized drug that could be harmful to health." Although some dietary supplements contain lovastatin-free RYR, little is known about how effective these supplements are for lowering cholesterol levels.

Suppliers of RYR tout its health benefits, but as with many nutraceuticals (foods with a medicinal benefit) there may be side effects, some of them serious. When improperly fermented, for example, RYR may contain citrinin, a poisonous substance that can cause kidney damage.

Health Benefits

RYR used in supplements is similar to what the Chinese have used for centuries in cooking and to help people with digestive or circulatory problems. RYR also contains beta-sitasterols and monounsaturated fatty acids, other nutrients that may help control cholesterol.

Significant amounts of the monacolin K found in RYR may lower cholesterol and associated lipids, the fatty acids that circulate in the bloodstream. This helps to reduce the risk of heart attack, stroke, and other cardiovascular (heart and blood vessel) diseases.

RYR may be easier to use for people who can't tolerate the side effects of statin drugs, but it's not without risks. One reason the FDA banned RYR products with lovastatin is that there's no way to ensure that the amount of monacolin K is the same in different supplement brands. It's hard to know what's in it, and people may not have a healthcare provider to oversee its use.

Cholestene is an example of a banned product: In July 2021, the FDA warned consumers that this widely available, over-the-counter RYR supplement contained lovastatin illegally. The FDA warned that this "undeclared drug ingredient" may cause side effects when combined with other medications. 

Researchers who looked at more than a dozen RYR studies concluded that it has real benefits and should remain classed as a food. But they also suggest a standard approach to making and labeling RYR products, so people know exactly what they're getting and know the risks.


Red yeast rice has been used in traditional medicine for centuries. It contains monacolin K, a natural form of the cholesterol-lowering drug lovastatin. But monacolin K is not approved by the FDA as a drug. Red yeast rice is available as a supplement and may offer health benefits, but there are also risks and side effects.

Precautions and Contraindications

It's important to discuss RYR with your healthcare provider to ensure that it's safe for you to take, given your health history and other current medications. The general reasons not to use RYR include:

  • Pregnancy: Do not use RYR supplements if you are pregnant, planning pregnancy, or nursing.
  • Statin drugs: If you're already on a prescription statin drug, don't take the supplement.
  • Use in children: Do not give RYR to children without talking to your child's healthcare team.

It's also important to evaluate the claims made by RYR suppliers, and your healthcare provider can help here too.

Red yeast rice and other nutraceuticals are not a substitute for professional health care, and your healthcare provider needs to know if you're taking a dietary supplement.

Side Effects

Because monacolin K is chemically identical to the lovastatin found in pharmaceuticals, the side effects are similar. Some may be serious, and include muscle pain, muscle damage, and kidney and liver damage. 

Common Side Effects

Not all side effects from RYR are severe. Some of the more common and mild side effects include dizziness, headaches, heartburn, and upset stomach.

Serious Side Effects

Prescription or natural lovastatin can cause severe muscle problems like myopathy, a type of damage to muscle tissue. It's also linked to rhabdomyolysis, a breakdown of muscle tissue that releases proteins from muscle fibers into the bloodstream.

These conditions can lead to kidney failure because of the stress they place on kidneys. The risk is greater in people who take higher doses of lovastatin, or take it in combination with certain antibiotics, other cholesterol-lowering medications, or some drugs used to treat fungal infections and HIV/AIDS.

Liver toxicity also is a concern, with some cases of hepatitis linked to RYR.

Alternatives to Red Yeast Rice

RYR is just one of many natural remedies touted as alternatives to cholesterol-lowering medications. Some research suggests that herbs like garlic and guggul may help curb cholesterol levels, as well.

There's also evidence that drinking green tea on a regular basis, increasing your soy intake, getting your fill of omega-3 fatty acids, and consuming plant sterols may help manage cholesterol.

Like red yeast rice, these alternative remedies may also cause certain side effects. To protect against the potentially adverse effects of any type of dietary supplement, it's important to use supplements safely.


The science on RYR has shown that the health benefits are real, at least in some people who take it to control their cholesterol levels. But the side effects are real too, and there are reasons why RYR is not safe for everyone. Talk with your healthcare provider before taking RYR supplements.

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8 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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Additional Reading
  • National Institutes of Health. "Red yeast: MedlinePlus Supplements."