Lipitor is a medication that belongs to a class of drugs called statins, which are used to lower cholesterol levels in the blood. Grapefruit and grapefruit juice contain compounds that can interfere with the metabolism of certain medications, including Lipitor. This can lead to higher levels of the drug in the blood, which can increase the risk of side effects.

According to the sources provided, it is generally recommended that people taking Lipitor avoid consuming grapefruit or grapefruit juice. The exact amount of grapefruit that is safe to consume while taking Lipitor is not clear, as the interaction between the two can vary depending on factors such as the individual's metabolism and the dose of Lipitor being taken. However, it is recommended to avoid grapefruit altogether to avoid any potential adverse effects.

It is important to note that the interaction between grapefruit and Lipitor is not unique to this medication, and can occur with other drugs as well. Patients should always consult with their healthcare provider or pharmacist before consuming grapefruit or grapefruit juice while taking any medication.

Sources:
[1] https://www.drugpatentwatch.com/p/tradename/LIPITOR
[2] https://ro.co/health-guide/lipitor-and-grapefruit/
[3] https://www.health.harvard.edu/heart-health/grapefruit-juice-and-statins