Does Grapefruit Affect Valerian Root?

Amount or timing may matter

The short answer

Valerenic acid is metabolized by CYP3A4. Grapefruit may increase valerian blood levels, leading to excessive sedation.

How to arrange timing

Avoid grapefruit within 4 hours of valerian to prevent excessive drowsiness.

Reference

Reference noted for this food and supplement combination: Donovan et al., Drug Metab Dispos 2004

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.