[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Pharmacology](https://durgical.com/en/pharmacology/) › [Herbal products and dietary supplements](https://durgical.com/en/pharmacology/classes/herbal-products-and-dietary-supplements/) › Red yeast rice # Red yeast rice ## Herbal products and dietary supplements? Herbal products and dietary supplements ## Pregnancy: contraindicated? There are no safety studies, so it is not recommended in pregnancy or breastfeeding. Rice fermented with Monascus mould. Some products contain monacolin K, identical to lovastatin, so they act, and harm, like a statin. Updated Nov 1, 2026 Also called: Monascus purpureus fermented rice, Monacolin K (= lovastatin) ## Quick facts **Group** [Herbal products and dietary supplements](https://durgical.com/en/pharmacology/classes/herbal-products-and-dietary-supplements/) **Target** HMG-CoA reductase (via monacolin K) **Used for** Promoted for high cholesterol **Key effects** Muscle pain · Digestive problems **Monitor** Lipid profile · Muscle symptoms No doses: the clinician sets them by the current guideline. On this page - The basics Mechanism of action - Indications - Adverse effects - Pharmacokinetics - Memory aid - Clinical What the labels mean - Safety Contraindications - Key interactions - What is monitored - Pregnancy and breastfeeding - Nursing care - Study Test yourself - Connections Connections ## Mechanism of action ✂**HMG-CoA reductase (via monacolin K)**Red yeast rice ⓘ The figure shows simvastatin, a close semi-synthetic relative of lovastatin (monacolin K), in the active site of human HMG-CoA reductase. **Target in 3D:** HMG-CoA reductase (via monacolin K). PDB structure 1HW9 (RCSB PDB, public domain). [View the structure at RCSB PDB](https://www.rcsb.org/structure/1HW9) · Drag to rotate · pinch to zoom Depending on the fungal strain and fermentation, the rice contains monacolins. Monacolin K has the same structure as lovastatin: it inhibits HMG-CoA reductase, the rate-limiting step of cholesterol synthesis, so the liver makes less cholesterol and takes up more LDL. Products high in monacolin K lower cholesterol; their content varies enormously, and some contain the kidney toxin citrinin. - Monacolin K (= lovastatin) is absorbed from the product - It inhibits HMG-CoA reductase in the liver - Less cholesterol synthesis, more LDL receptors - LDL falls; statin-type muscle and liver risks ## Indications - Promoted for high cholesterol: high-monacolin products may lower it; low-monacolin products may not work [Atherosclerosis and dyslipidaemia →](https://durgical.com/en/conditions/atherosclerosis-and-dyslipidaemia/) ## Adverse effects ### Common - Muscle pain - Digestive problems - Raised liver enzymes ### Serious (rare, important) - Statin-type muscle damage, liver injury and kidney damage - Kidney toxicity from citrinin contamination ## Contraindications - Use together with a prescribed statin - Pregnancy and breastfeeding - Liver disease or previous statin muscle injury ## Key interactions **Prescribed statins** Duplicate therapy and higher risk of muscle injury **Medicines that interact with statins (for example strong CYP3A4 inhibitors such as clarithromycin)** Higher monacolin K levels and myopathy risk, as with lovastatin ## What is monitored - Lipid profile - Muscle symptoms and creatine kinase if they appear - Liver and kidney function ## Pregnancy and breastfeeding There are no safety studies, so it is not recommended in pregnancy or breastfeeding. ## Nursing care - Ask every patient about herbal products and supplements and record them with the medicine list - Check that patients are not taking red yeast rice together with a prescribed statin - Teach to report unexplained muscle pain or dark urine - Teach that «natural» does not mean safe and that supplements are not approved as medicines before sale ## Pharmacokinetics **Absorption** Taken by mouth; the amount of monacolin K is rarely on the label and varies widely between brands ## Memory aid Red yeast rice = «a statin in disguise»: monacolin K is lovastatin. ## Test yourself Think of the answer, then tap the question to see it. ## Which statin is identical to monacolin K? Lovastatin. ## Why do red yeast rice products differ so much in effect? Monacolin K content varies widely between brands and is rarely stated on the label. ## Which contaminant of red yeast rice can damage the kidneys? Citrinin. [Add to my cards (3)](https://durgical.app/estudiar/?add=/en/pharmacology/red-yeast-rice/) [More Pharmacology questions →](https://durgical.com/en/practice/?f=pharmacology) ## What the labels mean **Pregnancy: contraindicated** There are no safety studies, so it is not recommended in pregnancy or breastfeeding. ## Connections ## Related drugs 2 - [Lovastatin](https://durgical.com/en/pharmacology/lovastatin/) - [Simvastatin](https://durgical.com/en/pharmacology/simvastatin/) ## Related conditions 1 - [Atherosclerosis and dyslipidaemia](https://durgical.com/en/conditions/atherosclerosis-and-dyslipidaemia/) [← Back to the class: Herbal products and dietary supplements](https://durgical.com/en/pharmacology/classes/herbal-products-and-dietary-supplements/) Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given. Sources: [Red Yeast Rice: What You Need To Know](https://www.nccih.nih.gov/health/red-yeast-rice) (National Center for Complementary and Integrative Health (NCCIH), 2022); [DailyMed - LOVASTATIN tablet](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=7b86160d-74a9-4774-b5b3-5641e686991f) (DailyMed (U.S. National Library of Medicine), 2026). ## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake Representative model, for educational purposes only. --- Source: https://durgical.com/en/pharmacology/red-yeast-rice/ License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/pharmacology/red-yeast-rice/