Lipitor is a brand name for the drug atorvastatin, which is used to treat high cholesterol. According to Drug Patent Watch [1], Lipitor is one of the most commonly prescribed medications in the United States, with over 100 million prescriptions written since its introduction in 1996. However, like all medications, Lipitor can cause side effects, including muscle pain.

According to the Mayo Clinic [2], muscle pain is one of the most common side effects of statins, a class of drugs that includes Lipitor. The exact prevalence of muscle pain caused by statins is difficult to determine, as it can vary widely depending on the population being studied and the definition of muscle pain being used. However, the Mayo Clinic notes that muscle pain occurs in up to 10% of people taking statins.

A recent study highlighted by the British Heart Foundation [3] found that a specific genetic variant may be responsible for some cases of statin-related muscle pain. The study found that people with a certain variant of the LILRB5 gene were more likely to experience muscle pain while taking statins. However, the study also noted that this genetic variant is relatively rare, and that most cases of statin-related muscle pain are likely caused by other factors.

In summary, muscle pain is a known side effect of Lipitor and other statins. The exact prevalence of this side effect is difficult to determine, but it is estimated to occur in up to 10% of people taking statins. A recent study suggests that a specific genetic variant may be responsible for some cases of statin-related muscle pain, but most cases are likely caused by other factors.

Sources:
[1] https://www.drugpatentwatch.com/p/tradename/LIPITOR
[2] https://www.mayoclinic.org/diseases-conditions/high-blood-cholesterol/in-depth/statin-side-effects/art-20046013
[3] https://www.bhf.org.uk/what-we-do/news-from-the-bhf/news-archive/2019/august/scientists-identify-potential-cause-of-statin-related-muscle-pain