Lipitor, also known as atorvastatin, is a medication used to lower cholesterol levels in the body. Grapefruit juice is known to interact with many medications, including some statins, which are a class of drugs that includes Lipitor. According to a study published in the Canadian Medical Association Journal, grapefruit juice can increase the absorption of atorvastatin, which may lead to an increased risk of side effects [3]. This is because grapefruit juice contains compounds that inhibit the enzymes responsible for breaking down atorvastatin in the liver, leading to higher levels of the drug in the bloodstream [2]. The effect of grapefruit juice on atorvastatin can vary from person to person, but it is generally recommended that patients taking Lipitor avoid consuming grapefruit juice [1][3]. Patients who are unsure about the safety of consuming grapefruit juice with Lipitor should consult with their healthcare provider before making any changes to their medication regimen [2].

Sources:
[1] https://www.drugpatentwatch.com/p/tradename/LIPITOR
[2] https://www.verywellhealth.com/can-i-take-lipitor-or-zocor-with-grapefruit-juice-1124045
[3] https://www.health.harvard.edu/heart-health/grapefruit-juice-and-statins