Does Grapefruit Affect Red Yeast Rice?

Use extra care with this combination

The short answer

Grapefruit inhibits CYP3A4, dramatically increasing blood levels of monacolin K (lovastatin) in red yeast rice. This raises the risk of rhabdomyolysis and liver damage.

How to arrange timing

Avoid grapefruit entirely while taking red yeast rice. CYP3A4 inhibition lasts up to 24 hours.

Reference

Reference noted for this food and supplement combination: FDA Drug Safety Communication; Bailey et al., CMAJ 2013

Important context

The effect can also change with food amount, supplement dose, product formulation, health conditions, and medication use. Ask a doctor or pharmacist first if you take medication, are pregnant or breastfeeding, or have a chronic condition.