Lipitor (atorvastatin) is a prescription medication that belongs to a class of drugs called statins. It is used to lower cholesterol levels and reduce the risk of heart attack and stroke. Grapefruit juice can interact with Lipitor and increase the risk of side effects.

According to Health Harvard [2], grapefruit juice contains a compound called furanocoumarin that inhibits an enzyme in the liver that metabolizes many drugs, including Lipitor. This leads to an increase in the level of Lipitor in the bloodstream, which can cause side effects such as muscle pain, liver damage, and kidney failure.

The amount of grapefruit juice that can interact with Lipitor varies depending on the individual and the dose of Lipitor they are taking. According to the drug patent watch [1], the recommended dose of Lipitor is 10-80 mg per day, and patients should avoid consuming more than 1 quart (32 ounces) of grapefruit juice per day.

RO Health [3] suggests that patients should avoid consuming grapefruit juice altogether while taking Lipitor to avoid any potential interactions. They also recommend talking to a healthcare provider before making any changes to medication or diet.

In conclusion, grapefruit juice can interact with Lipitor and increase the risk of side effects. The recommended amount of grapefruit juice to consume while taking Lipitor is no more than 1 quart (32 ounces) per day, but it is best to avoid grapefruit juice altogether to prevent any potential interactions. It is important to talk to a healthcare provider before making any changes to medication or diet.

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