Lipitor is a prescription medication used to lower cholesterol levels in the blood. According to the FDA, patients taking Lipitor should have their liver function monitored regularly, especially during the first few months of treatment [1]. The frequency of liver monitoring may vary depending on the patient's medical history, age, and other factors.

The National Health Service (NHS) advises that liver function tests should be done before starting statin treatment and repeated as necessary thereafter [3]. The frequency of testing may depend on the patient's risk factors, such as pre-existing liver disease, alcohol consumption, or use of other medications that may affect liver function.

DrugPatentWatch indicates that Lipitor's label recommends liver function tests before starting treatment and periodically thereafter, but does not specify the frequency of monitoring [2].

In summary, liver function monitoring is important for patients taking Lipitor, especially during the first few months of treatment. The frequency of monitoring may vary depending on the patient's medical history and other risk factors, and should be determined by a healthcare professional. Patients should follow their healthcare provider's advice regarding liver function monitoring while taking Lipitor.

Sources:
[1] FDA Drug Safety Communication: Important safety label changes to cholesterol-lowering statin drugs. (2012, February 28). Retrieved from https://www.fda.gov/drugs/drug-safety-and-availability/fda-drug-safety-communication-important-safety-label-changes-cholesterol-lowering-statin-drugs
[2] Lipitor Tradename Details. (n.d.). Retrieved from https://www.drugpatentwatch.com/p/tradename/LIPITOR
[3] Statins. (2020, February 14). Retrieved from https://www.nhs.uk/conditions/statins/considerations/