Red Yeast Rice - Zocor (Simvastatin) Interaction
Herbal: Red Yeast Rice
Also Known As: Monascus purpureus, Cholestin, Hong Qu, Hongqu, Koji Rouge, Mevinolin, Monacolin K, Monascus, Monascus Purpureus Went, Red Koji, Red Rice, Red Rice Yeast, Red Yeast Rice, Red Yeast Rice Extract, Riz Rouge, Rotschimmelreis, XueZhiKang, Xue Zhi Kang, XZK, Zhibituo, Zhitai, Zhi
Drug: Simvastatin
Brand names:
Zocor

Medical Content Editor Dr. Brian Staiger, PharmD
Last updated
May 25, 2025
Interaction Details
Simvastatin is classified as belonging to the following category: Hepatotoxic Drugs
Theoretically, concomitant use might increase the risk of liver damage.
Red yeast rice contains varying levels of the drug lovastatin. Lovastatin can cause liver damage in some people. Some clinical research suggests that supplements containing red yeast rice might increase liver enzyme levels in some, but not all, participants. Cases of acute hepatitis have been associated with red yeast rice. Combining it with hepatotoxic drugs might further increase this risk.
Interaction Rating
Likelihood of Occurrence
PossibleInteraction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists
References
- Roselle H, Ekatan A, Tzeng J, et al. Symptomatic hepatitis associated with the use of herbal red yeast rice. Ann Intern Med 2008;149:516-7.
- Huang, J., Frohlich, J., and Ignaszewski, A. P. The impact of dietary changes and dietary supplements on lipid profile. Can J Cardiol 2011;27(4):488-505.
- Grieco, A., Miele, L., Pompili, M., Biolato, M., Vecchio, F. M., Grattagliano, I., and Gasbarrini, G. Acute hepatitis caused by a natural lipid-lowering product: when "alternative" medicine is no "alternative" at all. J Hepatol 2009;50(6):1273-1277.
- Lin, C. C., Li, T. C., and Lai, M. M. Efficacy and safety of Monascus purpureus Went rice in subjects with hyperlipidemia. Eur J Endocrinol 2005;153(5):679-686.
- Prescribing Information. Mevacor (lovastatin). Whitehouse Station, NJ: Merck & Co., Inc., February 2012.
Interaction Details
Simvastatin is classified as belonging to the following category: Hmg-Coa Reductase Inhibitors ("Statins")
Theoretically, taking red yeast rice with other statins might increase the risk of potential adverse effects.
Red yeast rice contains varying levels of the statin drug lovastatin and might result in supratherapeutic levels when used with other statins. Based on evaluation of data from the US Food and Drug Administration's adverse event reporting system (FAERS), it is recommended that red yeast rice products be avoided in people taking prescription statins.
Interaction Rating
Likelihood of Occurrence
ProbableInteraction has not been documented in well-controlled studies, however, the interaction has been demonstrated in some small human studies or in controlled animal studies in conjunction with multiple case reports.
References
- Raschi E, Girardi A, Poluzzi E, et al. Adverse events to food supplements containing red yeast rice: comparative analysis of FAERS and CAERS reporting systems. Drug Saf 2018;41(8):745-52. doi: 10.1007/s40264-018-0661-3.
Red Yeast Rice Overview

Simvastatin Overview
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Simvastatin is used together with diet, weight-loss, and exercise to reduce the risk of heart attack and stroke and to decrease the chance that heart surgery will be needed in people who have heart disease or who are at risk of developing heart disease. Simvastatin is also used to decrease the amount of fatty substances such as low-density lipoprotein (LDL) cholesterol (''bad cholesterol'') and triglycerides in the blood and to increase the amount of high-density lipoprotein (HDL) cholesterol (''good cholesterol'') in the blood. Simvastatin may also be used to decrease the amount of cholesterol and other fatty substances in the blood in children and teenagers 10 to 17 years of age who have familial heterozygous hypercholesterolemia (an inherited condition in which cholesterol cannot be removed from the body normally). Simvastatin is in a class of medications called HMG-CoA reductase inhibitors (statins). It works by slowing the production of cholesterol in the body to decrease the amount of cholesterol that may build up on the walls of the arteries and block blood flow to the heart, brain, and other parts of the body.
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Accumulation of cholesterol and fats along the walls of your arteries (a process known as atherosclerosis) decreases blood flow and, therefore, the oxygen supply to your heart, brain, and other parts of your body. Lowering your blood level of cholesterol and fats with simvastatin has been shown to prevent heart disease, angina (chest pain), strokes, and heart attacks.
Red Yeast Rice - More Interactions
Red Yeast Rice interacts with 447 drugs
Interaction Rating Key
These severity listings are for informational use only. Never start, stop or otherwise change your therapy before speaking with your provider.
Major | The combined use of these agents is strongly discouraged as serious side effects or other negative outcomes could occur. |
Moderate | Use cautiously under the care of a healthcare professional or avoid this combination. A significant interaction or negative outcome could occur. |
Minor | Be aware that there is a chance of an interaction. Watch for warning signs of a potential interaction. |
Unknown | No interactions have been reported or no interaction data is currently available. |
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DISCLAIMER: Currently this does not check for drug-drug interactions. This is not an all-inclusive comprehensive list of potential interactions and is for informational purposes only. Not all interactions are known or well-reported in the scientific literature, and new interactions are continually being reported. Input is needed from a qualified healthcare provider including a pharmacist before starting any therapy. Application of clinical judgment is necessary.
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Drug descriptions are provided by MedlinePlus.