The Cholestin brand of red yeast rice has been generally well tolerated with possible temporary mild side effects such as heartburn, gas, and dizziness.²¹ This product should not be used by people with liver disorders²² and its safety during pregnancy has not been established.

There is one case report of muscle weakness and joint pain occurring in a man who was taking red yeast rice.²³ Because the man was also taking several prescription drugs, it was not clear whether the symptoms were caused by red yeast rice. In another case report, a woman developed severe muscle pain with laboratory evidence of muscle damage while taking red yeast rice. In that case, red yeast rice appeared to be the cause of the muscle damage.²⁴ These reports should be taken seriously, because muscle problems are common side effects of prescription HMG CoA-reductase inhibitors (statins). However, the frequency of side effects with red yeast rice is substantially lower than with statin drugs.²⁵

There is one case report of hepatitis developing in a woman taking red yeast rice. She was also taking two medications that have been reported to cause hepatitis, so a cause-effect relationship with red yeast rice was not proven. However, since statin drugs have been reported to cause hepatitis, it is possible that this complication can also result from taking red yeast rice.²⁶