Grapefruit oil has been known to interfere with the effectiveness of some medications, including Lipitor. Lipitor is a medication used to lower cholesterol levels in the blood [1]. According to the Mayo Clinic, grapefruit and grapefruit juice can interfere with the metabolism of certain medications, including Lipitor, by blocking an enzyme that is responsible for breaking down the medication in the body [2]. This can lead to higher levels of the medication in the bloodstream, increasing the risk of side effects.

The Tisserand Institute, which specializes in essential oil safety, also warns that grapefruit oil can interact with some medications, including Lipitor [3]. The institute recommends that individuals taking Lipitor should avoid using grapefruit oil or consuming grapefruit products.

In conclusion, grapefruit oil can interfere with the effectiveness of Lipitor, and individuals taking Lipitor should avoid consuming grapefruit products or using grapefruit oil. It is important to talk to a healthcare provider about any potential interactions between medications and supplements before starting a new treatment regimen.

Sources:
[1] https://www.drugpatentwatch.com/p/tradename/LIPITOR
[2] https://www.mayoclinic.org/healthy-lifestyle/consumer-health/expert-answers/food-and-nutrition/faq-20057918
[3] https://tisserandinstitute.org/learn-more/grapefruit-oil-and-medication/