There is one report of anaphylaxis (a severe allergic reaction) in a butcher who touched meat containing red yeast.
Side Effects and Warnings
There is limited evidence about the side effects of red yeast. Mild headache and abdominal discomfort can occur. Side effects may be similar to those for the prescription drug lovastatin (Mevacor®). Heartburn, gas, bloating, muscle pain or damage, dizziness, asthma, and kidney problems are possible. People with liver disease should not use red yeast products.
In theory, red yeast may increase the risk of bleeding. Caution is advised in patients with bleeding disorders or taking drugs that may increase the risk of bleeding. Dosing adjustments may be necessary. A metabolite of Monascus called mycotoxin citrinin (CTN) in fermentation may be harmful.
Pregnancy and Breastfeeding
Prescription drugs with similar chemicals as red yeast cannot be used during pregnancy. Therefore, it is strongly recommended that pregnant or breast-feeding women not take red yeast.
Adults (18 years and older):
1,200 milligrams of concentrated red yeast powder capsules have been taken two times per day by mouth with food.
The average consumption of naturally occurring red yeast rice in Asia has been reported as 14-55 grams per day.
Children (younger than 18 years):
There is not enough scientific evidence to recommend red yeast for children.
Interactions with Drugs
There are not many studies of the interactions of red yeast rice extract with drugs. However, because red yeast rice extract contains the same chemicals as the prescription drug lovastatin, the interactions may be the same. Fibrate drugs or other cholesterol -lowering medication may cause additive effects or side effects when taken with red yeast. Alcohol and other drugs that may be toxic to the liver should be avoided with red yeast rice extract. Taking cyclosporine, ranitidine (Zantac®) and certain antibiotics with red yeast rice extract may increase the risk of muscle breakdown or kidney damage.
Certain drugs may interfere with the way the body processes red yeast using the liver's "cytochrome P450" enzyme system. Inhibitors of cytochrome P450 may increase the chance of muscle and kidney damage if taken with red yeast.
In theory, red yeast may increase the risk of bleeding when taken with drugs that increase the risk of bleeding. Some examples include aspirin, anticoagulants ("blood thinners") such as warfarin (Coumadin®) or heparin, anti-platelet drugs such as clopidogrel (Plavix®), and non-steroidal anti-inflammatory drugs such as ibuprofen (Motrin®, Advil®) or naproxen (Naprosyn®, Aleve®).
Red yeast may produce gamma-aminobutyric acid (GABA), and therefore can have additive effects when taken with drugs that affect GABA such as neurontin (Gabapentin®).
Red yeast may also interact with digoxin, niacin, thyroid medications and blood pressure lowering medications. Caution is advised.
Red yeast may alter blood sugar levels in the blood, and patients with diabetes or taking insulin or blood sugar lowering medications by mouth should consult with a qualified healthcare professional, including a pharmacist. Dosing adjustments may be necessary.
Interactions with Herbs and Dietary Supplements
Red yeast may interact with products that cause liver damage or are broken down in the liver. Grapefruit juice may increase the blood levels of red yeast. Milk thistle, St. John's wort, niacin and vitamin A may interact with red yeast rice extract. Coenzyme Q levels may be lowered by red yeast rice extract. Cholesterol-lowering herbs and supplements like guggul or fish oils may have increased effects when taken with red rice yeast. Although not well studied, red yeast may also interact with astaxanthin and zinc. Caution is advised.
Certain herbs and supplements may interfere with the way the body processes red yeast using the liver's "cytochrome P450" enzyme system. Inhibitors of cytochrome P450 may increase the chance of muscle and kidney damage if taken with red yeast.
In theory, red yeast may increase the risk of bleeding when taken with herbs and supplements that are believed to increase the risk of bleeding. Multiple cases of bleeding have been reported with the use of Ginkgo biloba, and fewer cases with garlic and saw palmetto. Numerous other agents may theoretically increase the risk of bleeding, although this has not been proven in most cases.
Red yeast may also interact with digitalis (foxglove), or herbs and supplements that affect the thyroid or blood pressure. It may also have anti-inflammatory effects and should be used cautiously with other herbs or supplements that may have anti-inflammatory effects.
Red yeast may alter blood sugar levels in the blood, and patients with diabetes or taking herbs and supplement to control blood sugar should use with caution.