red yeast rice

Medically Reviewed on 12/14/2022

Generic Name: red yeast rice

Brand and Other Names: angkak, benikoji, hong qu, Monascus purpureus, red koji, red leaven, RYR, xuezhikang, zhi tai

Drug Class: Herbals

What is red yeast rice, and what is it used for?

Red yeast rice is a dietary supplement prepared by fermenting a type of yeast known as Monascus purpureus on rice. Red yeast rice has been used in China and other Asian countries for centuries as food and red yeast rice extract is used as a medicine to reduce blood cholesterol levels, and improve blood circulation and digestion. Reduction of blood cholesterol levels decreases the risk for cardiovascular diseases.

The fermentation of rice with M. purpureus enriches the rice with many bioactive substances including monacolin K, a natural chemical with structure similar to lovastatin, a cholesterol-lowering prescription drug. Like lovastatin, monacolin K reduces cholesterol levels by inhibiting 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, an enzyme involved in the biosynthesis of cholesterol. In addition, red yeast rice has isoflavones, monounsaturated fatty acids and sterols which may also have cholesterol lowering effects.

Traditional red yeast rice may contain only trace amounts of monacolin K, far less than the dosage used with lovastatin. Commercial red yeast rice products have been found to contain widely variable quantities of monacolin K. Some researchers have reported that lovastatin is illegally added to some red yeast rice products, and the FDA has issued warnings to these manufacturers. The FDA has requested withdrawal of red yeast products with high monacolin K, considered to be unapproved new drugs that cannot be legally sold in the U.S.

Some red yeast rice products may be contaminated by citrinin, a toxic substance that can damage the kidneys. An analysis of 37 red yeast rice products conducted in 2021 found that only one product had citrinin levels lower than the maximum level currently set by the European Union. Four products that were contaminated with citrinin were labeled citrinin-free.


  • Do not take if you are allergic to molds or any of the other ingredients in the red yeast rice product.
  • Do not take red yeast rice if you have liver disease, risk for liver disease, impairment of liver function or abnormal liver function tests.
  • Do not take red yeast rice if you have:
    • Kidney disease
    • Musculoskeletal disorders
    • Thyroid problems
    • High risk for cancer
    • Serious infection
    • Had an organ transplant
  • Do not take red yeast rice if you drink more than two alcoholic drinks a day.
  • Avoid red yeast rice if you are taking other drugs that are toxic to the liver.
  • Red yeast rice can cause muscle disease (myopathy) and breakdown of muscle fibers (rhabdomyolysis).

What are the side effects of red yeast rice?

Common side effects of red yeast rice include:

Call your doctor immediately if you experience any of the following symptoms or serious side effects while using this drug:

This is not a complete list of all side effects or adverse reactions that may occur from the use of this drug. Call your doctor for medical advice about serious side effects or adverse reactions. You may also report side effects or health problems to the FDA at 1-800-FDA-1088.


What is cholesterol? See Answer

What are the dosages of red yeast rice?

There isn’t enough scientific information on what might be an appropriate dosage of red yeast rice. Suggested dosage:


  • 1200 mg orally twice daily
  • Take with food


  • Overdose of red yeast rice can cause gastrointestinal discomfort, and muscle, kidney, and liver damage.
  • Overdose treatment may include discontinuation of red yeast rice and symptomatic and supportive care as required.

What drugs interact with red yeast rice?

Inform your doctor of all medications you are currently taking, who can advise you on any possible drug interactions. Never begin taking, suddenly discontinue, or change the dosage of any medication without your doctor’s recommendation.

The drug interactions listed above are not all of the possible interactions or adverse effects. For more information on drug interactions, visit the RxList Drug Interaction Checker.

It is important to always tell your doctor, pharmacist, or health care provider about all prescription and over-the-counter medications you use, as well as the dosage for each, and keep a list of the information. Check with your doctor or healthcare provider if you have any questions about the medication.

Pregnancy and breastfeeding

  • Red yeast rice may harm the fetus, do not take it if you are pregnant.
  • There isn’t enough information on use of red yeast rice by nursing mothers, avoid if you are breastfeeding.
  • Do not take any dietary supplement without first checking with your healthcare provider if you are pregnant or breastfeeding.

What else should I know about red yeast rice?

  • Take red yeast rice exactly as per label instructions. Do not take higher than recommended or more frequent doses.
  • Avoid taking red yeast rice for longer than 12 weeks, it is not known whether it is safe to take it for longer periods.
  • Check with your healthcare provider before taking any dietary supplement, including red yeast rice.
  • Dietary supplements often contain many ingredients. Check labels for the components in the red yeast rice product you choose.
  • It is impossible to know monacolin K quantities present in commercial red yeast rice products, because it is not usually included in the product labels.
    • A 2017 review analyzed 28 brands of red yeast rice products from mainstream retailers in the U.S., and none of them had the monacolin K quantity on the label.
    • Monacolin K was not found in two brands, and in the 26 brands that contained it, the quantity ranged from 0.09 to 5.48 mg per 1,200 mg of red yeast rice.
    • Red yeast products with high monacolin K levels are considered by the FDA to be unapproved new drugs and cannot be sold legally in the U.S.
  • Some researchers reported that commercial lovastatin is illegally added to some red yeast rice products. The FDA has sent warning letters to companies selling red yeast rice products that had added lovastatin, telling them to correct the violations.
  • Red yeast rice is marketed as a dietary supplement and is not stringently regulated by the FDA. Products may differ in formulations and strengths, and labels may not always match contents; exercise caution in choosing your product.
  • Red yeast rice products may be contaminated by citrinin, a toxic substance that can damage the kidney.
  • Store red yeast rice safely out of reach of children.
  • In case of overdose, seek medical help or contact Poison Control.


Red yeast rice has been used in China and other Asian countries for centuries as food and red yeast rice extract is used as a medicine to reduce blood cholesterol levels, and improve blood circulation and digestion. Common side effects of red yeast rice include nausea, diarrhea, stomach pain, gas (flatulence), heartburn, gastritis, dizziness, muscle pain and weakness, muscle damage (rhabdomyolysis), increased creatine phosphokinase, liver damage, and increase in blood levels of liver enzymes. Do not take red yeast rice if pregnant or breastfeeding.

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Medically Reviewed on 12/14/2022