Red yeast rice is the product of the fungus Monascus purpureus grown on rice. Red yeast rice is available in a powdered form that you can eat. It's also used in traditional Chinese medicine or sold as a supplement taken by mouth.

Red yeast rice has compounds in it that appear to lower cholesterol. One of the compounds is monacolin K. This compound has the same chemical structure as the prescription cholesterol-lowering medicine lovastatin (Altoprev).

Some people take red yeast rice as a supplement to try to lower cholesterol and improve their heart health.

Research on red yeast rice use for specific conditions shows:

• High cholesterol. Research shows that red yeast rice that has a large amount of the compound monacolin K in it can lower total cholesterol. The supplement also may lower low-density lipoprotein cholesterol, also called LDL cholesterol. This is the "bad" cholesterol found in the blood that can raise your risk of heart disease.

Caution

Red yeast rice can lower blood cholesterol. While the supplement is generally considered safe, it has the same potential side effects as prescription statin medicines used to treat high cholesterol.

Red yeast rice supplements are available without a prescription. But there's less of a guarantee about what's in a red yeast rice supplement compared with a statin. Some red yeast products might have only small amounts of monacolin K in them and might have little effect on cholesterol.

Red yeast rice can cause mild side effects, including:

• Stomach pain.
• Heartburn.
• Gas.
• Headache.
• Feeling dizzy.
• Upset stomach.

The monacolin K in red yeast rice has the same chemical structure as the prescription cholesterol-lowering medicine lovastatin. The supplement and man-made medicine can have similar side effects that are more serious. These may include liver, muscle, and kidney issues.

Don't take red yeast rice if you're pregnant, trying to become pregnant, or breastfeeding.

Red yeast rice supplements also could have citrinin in them. Citrinin is a toxin that can harm the kidneys. An analysis of 37 red yeast rice supplements found that only one had citrinin at safe levels.

Some medicines, supplements, and substances may not work well with red yeast rice. These include:

• Alcohol. Don't drink alcohol if you are taking red yeast rice. The combination might increase the risk of liver damage.
• Cyclosporine (Neoral, Sandimmune). This medicine suppresses the immune system. Taking it with red yeast rice might raise the risk of muscle issues.
• Cytochrome P450 3A4 inhibitors. Taking red yeast rice with medicines that slow down or stop the CYP3A4 enzyme might raise the risk of harmful side effects from red yeast rice. These medicines include erythromycin.
• Grapefruit. Drinking grapefruit juice and taking red yeast rice might raise the risk of the supplement's harmful side effects.
• Gemfibrozil (Lopid). Taking this cholesterol medicine with red yeast rice might raise the risk of muscle issues.
• Hepatotoxic medicines, herbs and supplements. Red yeast rice may have monacolin K in it, which can cause liver damage in some people. Taking red yeast rice with these types of medicines, herbs, and supplements could raise the risk of liver damage.
• Niacin. Taking red yeast rice with high-dose niacin might raise the risk of muscle issues.
• St. John's wort. Taking this supplement with red yeast rice might lessen how well the red yeast rice works.
• Statins. Taking red yeast rice with statins might raise the risk of harmful side effects.

March 27, 2025

Original article: https://www.mayoclinic.org/drugs-supplements-red-yeast-rice/art-20363074