Red Yeast Rice - Plan B (Levonorgestrel) 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: Levonorgestrel
Brand names:
Plan B, Mirena, Levonelle One Step, Levonelle 1500, Norgeston, Skyla, Liletta, Kyleena
Medical Content Editor Dr. Brian Staiger, PharmD
Last updated
Jun 22, 2025
Interaction Details
Levonorgestrel 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.
Red Yeast Rice Overview
Red yeast rice is a type of fermented rice produced by the cultivation of a type of yeast called Monascus purpureus. The rice is soaked in water and then allowed to ferment with the yeast for several weeks. During the fermentation process, the rice turns a deep red color and develops a distinctive, slightly sweet, and sour taste.
Red yeast rice has a long history of use in traditional medicine and has been used as a natural remedy for a range of health conditions, including high cholesterol, high blood pressure, and heart disease. Red yeast rice is thought to work by inhibiting the production of cholesterol in the liver and by helping to improve circulation.
Red yeast rice contains a compound known as mevinolin, which is identical to the FDA-approved drug lovastatin.
Levonorgestrel Overview
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Levonorgestrel is used to prevent pregnancy after unprotected sexual intercourse (sex without any method of birth control or with a birth control method that failed or was not used properly [e.g., a condom that slipped or broke or birth control pills that were not taken as scheduled]). Levonorgestrel should not be used to prevent pregnancy on a regular basis. This medication is to be used as an emergency contraceptive or backup in case regular birth control fails or is used incorrectly. Levonorgestrel is in a class of medications called progestins. It works by preventing the release of an egg from the ovary or preventing fertilization of the egg by sperm (male reproductive cells). It also may work by changing the lining of the uterus (womb) to prevent development of a pregnancy. Levonorgestrel may prevent pregnancy, but it will not prevent the spread of human immunodeficiency virus (HIV, the virus that causes acquired immunodeficiency syndrome [AIDS]) and other sexually transmitted diseases.
Red Yeast Rice - More Interactions
Red Yeast Rice interacts with 448 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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Parts of this content are provided by the Therapeutic Research Center, LLC.
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.
© 2021 Therapeutic Research Center, LLC
Drug descriptions are provided by MedlinePlus.
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Dr. Brian Staiger, PharmD
In addition to being a clinical pharmacist specializing in pharmacotherapy, Dr. Brian Staiger is a registered herbalist through the American Herbalist Guild. He has combined his passion for pharmacy practice with the study of medical ethnobotany to improve patient care. Feel free to reach out about any of your herbal or medication questions!
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