Lipitor is a brand name for atorvastatin, a medication used to lower cholesterol levels in the blood. According to the sources provided, muscle soreness or myalgia is a known side effect of atorvastatin [2][3]. A study published in the Journal of Clinical Lipidology found that patients taking atorvastatin experienced more muscle-related side effects than those taking other statins [2]. However, it is important to note that muscle soreness is a common symptom that can be caused by many factors, and it may not necessarily be directly related to the use of atorvastatin [3]. If you are experiencing muscle soreness while taking atorvastatin, it is recommended that you speak with your healthcare provider to determine the cause and discuss any potential adjustments to your medication regimen [3].

Sources:
[2] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2949584/
[3] https://www.mayoclinic.org/diseases-conditions/high-blood-cholesterol/in-depth/statin-side-effects/art-20046013