Red Yeast Rice

Purported Benefits, Side Effects & More

Red Yeast Rice

Purported Benefits, Side Effects & More
Red Yeast Rice

Common Names

  • Hong qu
  • Monascus
  • Red yeast
  • Beni-koji
  • Monacolin K

For Patients & Caregivers

Tell your healthcare providers about any dietary supplements you’re taking, such as herbs, vitamins, minerals, and natural or home remedies. This will help them manage your care and keep you safe.

What is it?

Red yeast rice appears to lower blood cholesterol and triglyceride levels, but it is not certain whether these products are safe to use.

Red yeast rice is a traditional Chinese medicinal product that also has culinary uses. It is made by culturing rice with specific strains of yeast. It is also marketed as a dietary supplement to reduce cholesterol and other fats in the blood. One of its constituents, monacolin K, also known as lovastatin, is an active ingredient in the cholesterol-lowering drug, Mevacor®. The drug works by inhibiting an enzyme essential for the creation of cholesterol in the body. Therefore, it is assumed that red yeast rice works through a similar mechanism.

Even though red yeast rice appears to reduce blood fats, it is not certain whether these products are safe. Some may contain a harmful contaminant or have side effects similar to certain cholesterol-lowering drugs. There have also been several case reports of adverse effects, so patients should discuss any use of this product with their healthcare provider.

What are the potential uses and benefits?
  • To lower high cholesterol

    A few clinical trials show that the use of red yeast rice can reduce cholesterol and triglyceride levels in the blood, but it is not certain whether these products are safe.
What are the side effects?
  • Stomach ache
  • Dizziness
  • Flatulence
  • Heartburn
  • Muscular disease resulting in muscle weakness

Case reports

  • Allergic reaction
  • Elevated liver enzymes
  • Liver injury, hepatitis
  • Unexpected high cholesterol
  • Skeletal muscle weakness and damage
  • Erectile dysfunction
What else do I need to know?

Patient Warnings:

  • Citrinin, a toxic fermentation byproduct, has been found in a number of red yeast rice preparations.
  • Grapefruit juice may increase the effects of red yeast rice.

Do Not Take if:

You are taking cholesterol-lowering drugs: Red yeast rice supplements contain variable amounts of monacolin K, the active ingredient in lovostatin. Side effects and interactions can be comparable to statin drugs, and long-term safety data is lacking.

You are taking CYP450 3A4 or P-glycoprotein substrate drugs: Lab studies show that red yeast rice extracts may affect drugs metabolized by these enzymes. Clinical relevance has yet to be determined.

Special Point:

The U.S. Food and Drug Administration declared that the dietary supplement Cholestin, manufactured by Pharmanex, cannot be marketed as a dietary supplement because it contained lovastatin, a prescription drug.

For Healthcare Professionals

Brand Name
Cholestin3 ™
Scientific Name
Monascus purpureus
Clinical Summary

Used in China as food and medicine for thousands of years, red yeast rice is the fermented product of the fungus, Monascus purpureus, grown on rice. It was first marketed as a dietary supplement in the United States by Pharmanex under the trade name Cholestin (1). The active constituent, monacolin K, is the same as lovastatin, an active ingredient in the cholesterol-lowering drug (2). A number of clinical trials have demonstrated effectiveness of red yeast rice preparations in reducing cholesterol levels in hyperlipidemic patients (3) (4) (5) (14) (15) (16) (17) (32), but meta-analyses are mixed on whether it is safe (24) (25) (33), with one citing a lack of regulation and standardized formulations. One of the extracts tested also did not lower blood pressure in hypertensive patients (20). In another study, co-supplementation with Coenzyme Q10 was found to be associated with improved LDL-cholesterolemia and endothelial reactivity in moderately hypercholesterolemic subjects (22).

It is important to note that several preparations of red rice yeast contain citrinin, a toxic fermentation byproduct (6).

Purported Uses and Benefits
  • High cholesterol
Mechanism of Action

Components such as citrinin, monacolines and monankarin, and monascopyridines have been isolated from red yeast rice (10). Fermentation products are standardized to contain 0.4% 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors. HMG-CoA reductase is the rate-limiting enzyme in endogenous cholesterol biosynthesis (1). The principal HMG-CoA reductase inhibitor is monacolin K, also known as lovastatin (11).

  • Citrinin, a toxic fermentation byproduct, was found at measurable concentrations in a number of preparations (6).
  • Grapefruit juice may increase the effects of red yeast rice (9).
Adverse Reactions

Stomach ache (3), heartburn, dizziness and flatulence (7), liver injury and myopathy (21) (23).

Case reports

  • Anaphylaxis: In a 26-year-old man (8).
  • Hypertransaminasemia: In a 63-year-old woman following use of Equisterol, an over-the-counter lipid-lowering product containing guggulsterol and red yeast rice extract, for 6 months. Symptoms normalized after product was discontinued (18).
  • Severe hepatitis: In a 62-year-old woman after use of red yeast rice capsules for 4 months. Condition improved after product was discontinued (19).
  • Acute liver injury: In a 64-year-old woman not on medications, and 6 weeks after starting a red yeast rice supplement to decrease cholesterol (27).
  • Paradoxical hypercholesterolemia: On routine screening in a 23-year-old man, attributed to downregulation of cholesteryl ester transfer protein with the use of red yeast rice extract (28). Symptoms disappeared after product discontinuation.
  • Rhabdomyolysis: In a 28-year-old renal transplant recipient (12).
  • Myasthenia gravis: Associated with use of red yeast rice supplements (29).
  • Erectile dysfunction: In a 39-year-old male patient who used red yeast rice for 3 weeks as self-therapy to lower blood fats. Symptoms disappeared about 5 weeks after product discontinuation (26).
  • Eosinophilic esophagitis: In a 58-year-old male, with symptoms appearing 12 months after starting red yeast rice for hypercholesterolemia. Symptoms resolved within days of discontinuing the product (34).
Herb-Drug Interactions

Statin drugs: Red yeast rice supplements contain variable amounts of monacolin K, the active ingredient in lovostatin. Side effects and interactions can be comparable to statin drugs, and long-term safety data is lacking (30).

CYP450 3A4 and P-glycoprotein substrates: Preclinical studies show that red yeast rice extracts can inhibit CYP3A4 and P-gp, and may affect drugs metabolized by these enzymes (31). Clinical relevance has yet to be determined.

Dosage (OneMSK Only)
  1. Schulz V, Hansel R, Tyler VE. Rational Phytotherapy: A Physician’s Guide to Herbal Medicine. New York: Springer, 2001.
  2. FDA Talk Paper. FDA determines Cholestin to be an unapproved drug. T98-28. May 20, 1998.
  3. Wang J, et al. Multicenter clinical trial of the serum lipid-lowering effects of a Monascus purpureus (red yeast) rice preparation from traditional Chinese medicine. Curr Ther Res Clin Exp. 1997 58(12):964-978.
  4. Heber D, et al. Cholesterol-lowering effects of a proprietary Chinese red-yeast-rice dietary supplement. Am J Clin Nutr 1999 Feb;69(2):231-6.
  5. Keithley JK, Swanson B, Sha BE, Zeller JM, Kessler HA, Smith KY. A pilot study of the safety and efficacy of cholestin in treating HIV-related dyslipidemia. Nutrition 2002;18:201-4.
  6. Heber D, Lembertas A, Lu QY, Bowerman S, Go VL. An analysis of nine proprietary Chinese red yeast rice dietary supplements: implications of variability in chemical profile and contents. J Altern Complement Med 2001;7:133-9.
  7. Thompson Coon JS, Ernst E. Herbs for serum cholesterol reduction: a systematic review. J Fam Pract 2003 Jun;52(6):468-78.
  8. Wigger-Alberti W, Bauer A, Hipler UC, Elsner P. Anaphylaxis due to Monascus purpureus—fermented rice (red yeast rice). Allergy 1999;54:1330-1.
  9. Kantola T, Kivisto KT, Neuvonen PJ. Grapefruit juice greatly increases serum concentrations of lovastatin and lovastatin acid. Clin PharmacolTher. 1998;63:397-402.
  10. Wild D, Toth G, Humpf HU. New monascus metabolites with a pyridine structure in red fermented rice. J Agric Food Chem. 2003;51:5493-6.
  11. Chang YN, Lin YC, Lee CC, Liu BL, Tzeng YM. Effect of rice—glycerol complex medium on the production of Lovastatin by Monascus ruber. Folia Microbiol.(Praha) 2002;47:677-84.
  12. Prasad GV, Wong T, Meliton G, Bhaloo S. Rhabdomyolysis due to red yeast rice (Monascus purpureus) in a renal transplant recipient. Transplantation 2002;74:1200-1.
  13. Ghirlanda G, Oradei A, Manto A, et al. Evidence of plasma CoQ10-lowering effect by HMG-CoA reductase inhibitors: a double-blind, placebo-controlled study. J Clin Pharmacol. 1993;33:226-9.
  14. Lin CC, Li TC, Lai MM. Efficacy and safety of Monascus purpureus Went rice in subjects with hyperlipidemia. Eur J Endocrinol 2005;153(5):679-86.
  15. Huang CF, Li TC, Lin CC, et al. Efficacy of Monascus purpureus Went rice on lowering lipid ratios in hypercholesterolemic patients. Eur J Cardiovasc Prev Rehabil. 2007;14(3):438-40.
  16. Becker DJ, Gordon RY, Morris PB, et al. Simvastatin vs therapeutic lifestyle changes and supplements: randomized primary prevention trial. Mayo Clin Proc. 2008;83(7):758-64.
  17. Becker DJ, Gordon RY, Halbert SC, et al. Red yeast rice for dyslipidemia in statin-intolerant patients: a randomized trial. Ann Intern Med 2009;150(12):830-9, W147-9.
  18. Grieco A, Miele L, Pompili M, et al. Acute hepatitis caused by a natural lipid-lowering product: when “alternative” medicine is no “alternative” at all. J Hepatol. 2009 Jun;50(6):1273-7.
  19. Roselle H, Ekatan A, Tzeng J, Sapienza M, Kocher J. Symptomatic hepatitis associated with the use of herbal red yeast rice. Ann Intern Med. 2008 Oct 7;149(7):516-7.
  20. Li JJ, Lu ZL, Kou WR, et al. Long-term effects of Xuezhikang on blood pressure in hypertensive patients with previous myocardial infarction: data from the Chinese Coronary Secondary Prevention Study (CCSPS). Clin Exp Hypertens. 2010;32(8):491-8.
  21. Lapi F, Gallo E, Bernasconi S, et al. Myopathies associated with red yeast rice and liquorice: spontaneous reports from the Italian Surveillance System of Natural Health Products. Br J Clin Pharmacol. 2008 Oct;66(4):572-4.
  22. Cicero AF, Morbini M, Rosticci M, et al. Middle-Term Dietary Supplementation with Red Yeast Rice Plus Coenzyme Q10 Improves Lipid Pattern, Endothelial Reactivity and Arterial Stiffness in Moderately Hypercholesterolemic Subjects. Ann Nutr Metab. 2016;68(3):213-9.
  23. Mazzanti G, Moro PA, Raschi E, et al. Adverse reactions to dietary supplements containing red yeast rice: assessment of cases from the Italian surveillance system. Br J Clin Pharmacol. Apr;83(4):894-908.
  24. Peng D, Fong A, Pelt AV. Original Research: The Effects of Red Yeast Rice Supplementation on Cholesterol Levels in Adults. Am J Nurs. Aug 2017;117(8):46-54.
  25. Fogacci F, Banach M, Mikhailidis DP, et al. Safety of red yeast rice supplementation: A systematic review and meta-analysis of randomized controlled trials. Pharmacol Res. May 2019;143:1-16.
  26. Liu Z, Chen P. A case of erectile dysfunction induced by red yeast rice in lipid-lowering therapy. Phytother Res. May 2018;32(5):953-954.
  27. Loubser L, Weider KI, Drake SM. Acute liver injury induced by red yeast rice supplement. BMJ Case Rep. Mar 25 2019;12(3).
  28. McPherson PA. Paradoxical Hypercholesterolemia in an Otherwise Healthy Adult Man. Lab Med. Mar 10 2020;51(2):217-220.
  29. Dobremez V, Serra A, Grosset-Janin D, et al. Myasthenia gravis exacerbation after red yeast rice use. Rev Neurol (Paris). Sep-Oct 2018;174(7-8):577-578.
  30. Farkouh A, Baumgärtel C. Mini-review: medication safety of red yeast rice products. Int J Gen Med. 2019;12:167-171.
  31. Fung WT, Subramaniam G, Lee J, et al. Assessment of extracts from red yeast rice for herb-drug interaction by in-vitro and in-vivo assays. Sci Rep. 2012;2:298.
  32. Minamizuka T, Koshizaka M, Shoji M, et al. Low dose red yeast rice with monacolin K lowers LDL cholesterol and blood pressure in Japanese with mild dyslipidemia: A multicenter, randomized trial. Asia Pac J Clin Nutr. 2021 Sep;30(3):424-435.
  33. Li P, Wang Q, Chen K, et al. Red Yeast Rice for Hyperlipidemia: A Meta-Analysis of 15 High-Quality Randomized Controlled Trials. Front Pharmacol. 2022 Jan 17;12:819482.
  34. Janmohamed SR, Alsaad WK, Gutermuth J, Grosber M. Eosinophilic esophagitis due to red yeast rice (Monacoline K) in a dietary supplement for hypercholesterolemia. Clin J Gastroenterol. 2021 Apr;14(2):407-409.
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