Does Grapefruit Affect Milk Thistle?

Amount or timing may matter

The short answer

Silymarin in milk thistle inhibits CYP3A4 and P-glycoprotein, similar to grapefruit. Combining both may cause additive enzyme inhibition affecting other supplements.

How to arrange timing

Be cautious combining milk thistle with grapefruit, especially if taking other CYP3A4-metabolized supplements.

Reference

Reference noted for this food and supplement combination: Sridar et al., Drug Metab Dispos 2004; Examine.com

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.