Doctors warn against consuming Grapefruit juice if you take certain types of medication, such as statins, which are metabolized by the CYP3A4 enzyme. Grapefruit juice inhibits this enzyme so the liver produces less of it, and this affects the action of those drugs – they will be less effective. This is known as a drug interaction. Should you also be careful when using the essential oil?
Grapefruit juice interaction is primarily due to dihydroxybergamottin, which is not present in the essential oil. Another interacting Grapefruit juice constituent is bergamottin, which is found in the oil, but the action of bergamottin on enzymes is relatively weak. So for Grapefruit oil there is no risk, unless you ingest a significant quantity. We don’t know exactly how much, but probably at least 1mL per day. No known interactions with citrus oils have ever been recorded.