Is it safe to take metoprolol with red yeast rice supplements?

Taking metoprolol with red yeast rice is generally not known to cause a direct drug–drug interaction, but there are important safety points you should consider because red yeast rice can act like a statin and may affect how other medicines are processed. ^[1] Red yeast rice products contain variable amounts of monacolin K (lovastatin), so side effects may resemble those of prescription statins, and quality varies widely. ^{[2] [3]}

What red yeast rice does

• Red yeast rice contains monacolin K, which is chemically identical to lovastatin, a cholesterol‑lowering drug. This means its benefits and side effects can mirror statins. ^[4]
• Some formulations can inhibit drug‑processing proteins (CYP3A4 and P‑glycoprotein) in lab studies, though the real‑world impact on most medicines remains uncertain. ^[5]
• Reported side effects include muscle problems (myopathy), liver injury, dizziness, and gastrointestinal symptoms; rare cases of severe reactions have been described. Because supplement content varies, risk can be unpredictable. ^{[6] [7]}

Metoprolol overview

• Metoprolol (a beta‑blocker) is primarily cleared by the liver enzyme CYP2D6, not CYP3A4. Known significant interactions are mainly with certain antidepressants that inhibit CYP2D6 (e.g., paroxetine, fluoxetine, bupropion), which can raise metoprolol levels and cause slow heart rate or heart block. ^[8]
• There is no well‑documented direct interaction between metoprolol and red yeast rice in clinical studies. However, caution is reasonable due to red yeast rice’s statin‑like effects and potential to affect drug metabolism in lab settings. ^[5]

Practical safety guidance

• Based on available evidence, taking metoprolol with red yeast rice can be acceptable for many people, since metoprolol’s main interaction pathway (CYP2D6) is different from the enzyme systems most implicated with red yeast rice. ^{[8] [5]}
• Still, it’s wise to use red yeast rice carefully:
  • Choose reputable products, as monacolin content varies widely and contamination (e.g., citrinin) has been found in several commercial brands. This variability affects both efficacy and safety. ^[3]
  • Avoid combining red yeast rice with other drugs known to increase statin toxicity (e.g., gemfibrozil), alcohol, strong CYP3A4 inhibitors, or grapefruit, which can raise the risk of liver or muscle problems. These combinations have clearer evidence of harm. ^{[1] [9] [10]}
  • Monitor for symptoms of statin‑type side effects: new muscle pain or weakness, dark urine, unusual fatigue, or right‑upper abdominal pain seek medical advice if these occur. ^[6]
  • Consider periodic liver enzyme checks if you plan to use red yeast rice regularly, similar to monitoring with statins, because liver injury has been reported. ^[6]

What to watch for specifically with metoprolol

• Metoprolol side effects to monitor include slow heart rate, dizziness, fatigue, or fainting; these are usually related to dose, other heart‑slowing drugs, or CYP2D6‑inhibiting antidepressants rather than red yeast rice. ^[8]
• If you take other heart medicines (like verapamil or diltiazem), be extra cautious because combinations with metoprolol can increase the risk of heart conduction problems, independent of red yeast rice. ^[11]
• If you are on any CYP2D6‑inhibiting antidepressants, discuss metoprolol dosing with your clinician since levels can rise 2–6 fold; this is separate from red yeast rice but very relevant to overall safety. ^[8]

Bottom line

• There is no strong evidence of a harmful interaction between metoprolol and red yeast rice, and many people may take them together without issues. ^{[8] [5]}
• The main risks come from the red yeast rice side (statin‑like effects, variable quality, potential liver/muscle issues) and from metoprolol’s known interactions with CYP2D6‑inhibiting antidepressants or other heart‑rate‑lowering drugs. If you choose to use red yeast rice, do so thoughtfully and monitor for symptoms. ^{[6] [8] [11]}
• As with any supplement that acts like a prescription drug, it’s best to discuss with your clinician, especially if you have liver disease, drink alcohol, take interacting medications, or have a history of statin intolerance. ^{[1] [9] [10]}