Lipitor is a statin drug used to lower cholesterol levels in the body. Grapefruit and its juice contain a group of chemicals called furanocoumarins, which can interfere with the metabolism of certain drugs, including Lipitor. Grapefruit can increase the level of Lipitor in the bloodstream, leading to a higher risk of side effects. According to GoodRx [2], grapefruit should be avoided while taking Lipitor as it can increase the risk of muscle pain, liver damage, and kidney failure. The NHS [3] also advises against consuming grapefruit while taking Lipitor, as it can increase the risk of side effects. Drug Patent Watch [1] states that Pfizer, the manufacturer of Lipitor, recommends that patients avoid consuming grapefruit or grapefruit juice while taking Lipitor. In conclusion, grapefruit can increase the side effects of Lipitor, and it is recommended to avoid consuming grapefruit or grapefruit juice while taking Lipitor.

Sources:
[1] https://www.drugpatentwatch.com/p/tradename/LIPITOR
[2] https://www.goodrx.com/classes/statins/why-cant-i-have-grapefruit-with-my-statin
[3] https://www.nhs.uk/common-health-questions/medicines/does-grapefruit-affect-my-medicine/