In 53 trials red yeast rice caused no more muscle complaints than control, yet regulators log rare statin-type injuries. Both are true, and 3 situations turn a rare risk into a likely one.
Those 3 are a second statin, a drug that blocks its breakdown, and a contaminated product.
Quick Answer: What Are the Side Effects of Red Yeast Rice?
In 53 trials, red yeast rice caused no more muscle complaints than control, but it carries statin risks: muscle pain, rarely rhabdomyolysis, and rare liver injury. A prescribed statin, grapefruit juice or cyclosporine raises that risk. Citrinin contamination can harm the kidneys, and it is not recommended in pregnancy or breastfeeding.
Key Takeaways
- 53 trials with 8,535 people found no extra muscle risk versus control.
- US reports logged 27 rhabdomyolysis or myopathy cases linked to red yeast rice.
- Double-strength grapefruit juice raised lovastatin exposure 15-fold in 1 study.
- EFSA reports serious reactions at monacolin K intakes as low as 3 mg.
- A Japanese survey found 192 kidney injury patients linked to beni-koji tablets.
Related Products
What Trials Show About Side Effects
Start with the controlled evidence, because it is reassuring, and then look at its limits.
- 53 trials, 8,535 people: No increase in muscle and joint complaints.
- Other side effects: Fewer than control, an odds ratio of 0.59.
- Umbrella review, 2024: 5 links to harm, for uric acid, ALT and AST.
- Confidence: 12 of 15 meta-analyses rated critically low.
The 2019 safety review pooled those 53 trials.[1]Safety of red yeast rice supplementation: a systematic review and meta-analysis of randomized controlled trials — Pharmacological Research (2019) View source The 2024 umbrella review graded the credibility of that evidence.[2]Associations between the use of red yeast rice preparations and adverse health outcomes: an umbrella review — Journal of Integrative Medicine (2024) View source
Trials choose their participants and their products, so rare harms show up in reports instead. Why red yeast rice behaves like a statin at all is covered in our red yeast rice guide.
Muscle Problems
Muscle injury is the statin side effect people fear most, and red yeast rice can cause it.
- Warning signs: Pain, tenderness, weakness or dark urine.
- Severe form: Rhabdomyolysis, muscle breakdown that strains the kidneys.
- US reports: 27 rhabdomyolysis or myopathy cases, 2004 to 2017.
- France: 15 muscle cases, 3 of them rhabdomyolysis.
The warning signs are those listed for lovastatin.[3]Lovastatin Drug Information — MedlinePlus, National Library of Medicine View source The US figure comes from FDA's food reporting system.[4]Adverse Events to Food Supplements Containing Red Yeast Rice: Comparative Analysis of FAERS and CAERS — Drug Safety (2018) View source The French series combined national and published cases.[5]Red yeast-rice-induced muscular injuries: analysis of French pharmacovigilance database — Therapie (2023) View source
A 2023 review of FDA reporting systems judged such cases extremely rare compared with statins.[6]Rhabdomyolysis or Severe Acute Hepatitis Associated with the Use of Red Yeast Rice Extracts — Current Atherosclerosis Reports (2023) View source
Liver Effects
Liver injury is rarer still, but documented.
- LiverTox score: C, a probable rare cause of liver injury.
- Controlled trials: No enzyme rises in extract trials.
- Case reports: Hepatitis within weeks of starting, easing once stopped.
- Alcohol: Raises the risk of serious lovastatin side effects.
LiverTox describes isolated case reports despite clean trial data.[7]Red Yeast Rice, LiverTox — National Institute of Diabetes and Digestive and Kidney Diseases View source In 1 case, a 64-year-old woman developed hepatitis 6 weeks after starting.[8]Acute liver injury induced by red yeast rice supplement — BMJ Case Reports (2019) View source The alcohol warning comes from the same lovastatin information cited above.
The 9 herbs in our blend have not been tested as liver protection, so we list a blended red yeast rice capsule under the same cautions as plain red yeast rice.
Drug and Food Interactions
Lovastatin is broken down by an enzyme called CYP3A4. Anything that blocks it can raise monacolin K levels.
| Combination | Why it matters | Evidence |
|---|---|---|
| A prescribed statin | 2 drugs of 1 class at once | Monacolin K is lovastatin |
| Double-strength grapefruit juice | Blocks CYP3A4 in the gut | Lovastatin exposure up 15-fold |
| 1 glass of regular grapefruit juice | A smaller effect | Lovastatin exposure roughly doubled |
| Cyclosporine | Raises statin levels | Rhabdomyolysis in a kidney transplant patient |
| Other medicines flagged for lovastatin | Same interaction types | Ask your pharmacist |
The 15-fold rise came with double-strength juice taken 3 times a day.[9]Grapefruit juice greatly increases serum concentrations of lovastatin and lovastatin acid — Clinical Pharmacology and Therapeutics (1998) View source One daily glass of regular juice had a smaller effect.[10]Grapefruit juice has minimal effects on plasma concentrations of lovastatin-derived HMG-CoA reductase inhibitors — Clinical Pharmacology and Therapeutics (1999) View source
The cyclosporine case resolved once the product was stopped.[11]Rhabdomyolysis due to red yeast rice (Monascus purpureus) in a renal transplant recipient — Transplantation (2002) View source NCCIH notes red yeast rice can have the same interaction types as statins.[12]Red Yeast Rice — National Center for Complementary and Integrative Health View source
Kidneys and Citrinin
Kidney harm can come from 2 directions: muscle breakdown, and toxins made during fermentation.
- Citrinin: A mold toxin that targets the kidneys.
- Found: High in 4 of 12 US products tested in 2010.
- Japan: 192 patients with kidney injury after beni-koji tablets.
- That cause: Not citrinin, which the implicated strains did not produce.
Citrinin is mainly a kidney toxin.[13]A comprehensive review on biological properties of citrinin — Food and Chemical Toxicology (2017) View source The 2010 survey measured it.[14]Marked variability of monacolin levels in commercial red yeast rice products — Archives of Internal Medicine (2010) View source
In the Japanese survey, 87% still had reduced kidney function at last follow-up.[15]A nationwide questionnaire study evaluated kidney injury associated with Beni-koji tablets in Japan — Kidney International (2025) View source How to judge a product for this is covered in the citrinin contamination problem.
Pregnancy, Breastfeeding and Other Groups
Some people should not take red yeast rice at all.
- Pregnancy and breastfeeding: Not recommended, with 0 safety studies.
- Liver disease or heavy drinking: Avoid.
- Kidney disease: Avoid unless a specialist agrees.
- Transplant on cyclosporine: Avoid.
- Past statin muscle injury: Discuss first.
NCCIH, cited above, does not recommend it in pregnancy or lactation, and the lovastatin information warns it may harm the fetus. A 2016 Dutch review also flagged serious risks in pregnancy.[16]Red yeast rice as a cholesterol-lowering substance? Caution is warranted — Nederlands Tijdschrift voor Geneeskunde (2016) View source
If You Take It Anyway
If a clinician agrees you can try it, a few rules lower the risk.
- Never: With a prescribed statin.
- Skip: Grapefruit juice.
- Stop: For unexplained muscle pain or dark urine, and get checked.
- Recheck: Lipids and liver tests as advised.
Dose, timing and duration are in how much to take and when.
Stop and Speak to a Clinician If
- You take a prescribed statin or any other cholesterol medicine
- You are pregnant, trying to conceive or breastfeeding
- You have liver or kidney disease, or drink alcohol heavily
- You take cyclosporine, or medicines your pharmacist flags for lovastatin
- You have had muscle pain, weakness or dark urine on a statin before
Frequently Asked Questions
What are the bad side effects of red yeast rice? +
Muscle pain and, rarely, rhabdomyolysis; rare liver injury; and kidney harm from contaminants. US reports logged 27 rhabdomyolysis or myopathy cases by 2017.
What medications cannot be taken with red yeast rice? +
Prescribed statins, cyclosporine and other medicines that interact with lovastatin. Grapefruit juice raised lovastatin exposure 15-fold in 1 study.
Who should avoid taking red yeast rice? +
Anyone pregnant or breastfeeding, people on a statin or cyclosporine, and anyone with liver or kidney disease. NCCIH notes 0 safety studies in pregnancy.
Are there any dangers in taking red yeast rice on a long term basis? +
Long-term data are thin; the longest trial ran 4.5 years with a Chinese extract. Statin-type muscle and liver effects can appear at any point, so periodic checks matter.
What supplements should you not take with red yeast rice? +
Any other red yeast rice or monacolin product, including blends and packs that already contain it. Doubling up adds a second unknown dose of 1 statin compound.
Can you take vitamin D with red yeast rice? +
No interaction has been studied. Of 9 PubMed records mentioning both, none tested taking them together, so ask your pharmacist.
Is red yeast rice bad for your kidneys? +
It can be. Citrinin, a kidney toxin, was high in 4 of 12 US products in 2010, and severe muscle breakdown can also injure the kidneys.
Can I drink grapefruit juice with red yeast rice? +
Best avoided. Double-strength juice raised lovastatin exposure 15-fold, and even 1 daily glass of regular juice roughly doubled it.
Can you drink alcohol with red yeast rice? +
Keep it minimal and ask your clinician. The lovastatin information warns alcohol raises the risk of serious side effects, and 1 published hepatitis case began 6 weeks after starting.
Is red yeast rice safe during pregnancy? +
No. NCCIH does not recommend it in pregnancy or breastfeeding, there are 0 safety studies, and lovastatin may harm the fetus.
Related Reading
Related Products
