Lipitor (atorvastatin) is a medication used to lower cholesterol levels in the blood. According to the FDA, patients taking Lipitor should be monitored for liver function tests before starting the medication and periodically thereafter [3]. The frequency of monitoring liver function tests is not specified, but it is recommended that patients with pre-existing liver disease or who consume large amounts of alcohol should be monitored more closely [3].

A study published in the Journal of the American College of Cardiology recommends that patients taking atorvastatin, like Lipitor, should have their cholesterol levels checked within four to twelve weeks after starting the medication, and then every three to twelve months thereafter [2]. The study also suggests that the frequency of monitoring should be based on the patient's individual risk factors for cardiovascular disease and their response to the medication [2].

It is important to note that the optimal frequency of monitoring may vary depending on the patient's individual circumstances, such as their age, overall health, and other medications they may be taking. Patients should consult with their healthcare provider to determine the appropriate monitoring schedule for their specific situation.

In conclusion, patients taking Lipitor should have their liver function tests monitored periodically, and their cholesterol levels checked within four to twelve weeks after starting the medication, and then every three to twelve months thereafter [2][3]. The frequency of monitoring should be based on the patient's individual risk factors for cardiovascular disease and their response to the medication [2]. Patients should consult with their healthcare provider to determine the appropriate monitoring schedule for their specific situation.

Sources:
[2] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4110821/
[3] https://www.fda.gov/drugs/drug-safety-and-availability/fda-drug-safety-communication-important-safety-label-changes-cholesterol-lowering-statin-drugs