Red yeast rice is produced by the fermentation of rice by a yeast, Monascus purpureus. This rice is served as a food in Asian countries. It is also available as a nutritional supplement that is used to maintain or lower cholesterol levels. Additionally, red yeast extract is used to aid blood circulation, indigestion, spleen health and stop diarrhea. The active ingredient in red yeast extract, monocolin K, has the same chemical makeup as the cholesterol medication lovastatin, and thus the same benefits as well as some of the same side effects. In the United States, red yeast extracts containing lovastatin have been classified as a drug by the U.S. Food and Drug Administration and removed from the market.
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Although it is generally well-tolerated by most people, one of the more serious side effects of red yeast extract is the development of muscle pain. Red yeast extract can cause a breakdown of muscle tissue called rhabdomyolysis. The symptoms include muscle pain, tenderness and weakness. Breakdown of muscle tissue in this way can lead to kidney damage over time. The risk is greater for those taking high doses of this extract, or taking it along with lovastatin. Any sign of muscle pain and weakness should be reported to a physician and the use of red yeast extract should be discontinued immediately.
Increased Bleeding Risk
It's possible that red yeast extract may increase the risk of bleeding in the same way lovastatin does, according to MayoClinic.com. Those with bleeding disorders, such as Von Willebrand Disease, and those taking blood-thinning medications such as warfarin should only take red yeast extract under the supervision of a physician, as the dosages of their medications may have to be adjusted.
Red yeast extract can also cause liver damage. The symptoms of liver damage include yellowing of the eyes and skin, elevated liver enzymes and dark urine. Those with liver disease should not take red yeast extract without first consulting a physician. Alcoholic beverages and medications that affect the liver, such as acetaminophen, erythromycin, phenytoin and other statin cholesterol drugs, should be avoided while taking red yeast extract.
There have been allergic reactions reported with the use of red yeast extract. The signs of an allergic reaction should not be ignored. They include itching and hives, difficulty breathing, swelling of the face, tongue and throat, along with difficulty swallowing. The supplement should be discontinued and a physician contact if any symptoms of an allergic reaction develop.
Heartburn and Indigestion
As with many nutritional supplements, it is possible for red yeast extract to cause some gastrointestinal side effects, including heartburn and indigestion. It can also cause gas and bloating.
It is crucial to choose a red yeast extract made by a reputable company. MedlinePlus warns that red yeast that is not properly fermented contains a substance, citrinin, that is toxic to the kidneys.