Lipitor is a medication used to lower cholesterol levels in the blood [1]. According to the Mayo Clinic, some common side effects of statins like Lipitor include muscle pain and weakness [2]. The National Center for Biotechnology Information states that while statin-induced myopathy (muscle pain and weakness) is a common side effect, it is generally not severe enough to limit physical activity [3].

As for taking pain medication while exercising on Lipitor, it is recommended to consult with a healthcare provider. The Mayo Clinic suggests that if muscle pain or weakness is experienced while taking Lipitor, it is important to talk to a healthcare provider before taking any over-the-counter pain medication [2].

In conclusion, while muscle pain and weakness are common side effects of Lipitor, they are generally not severe enough to limit physical activity. However, it is recommended to consult with a healthcare provider before taking any pain medication while exercising on Lipitor.

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.ncbi.nlm.nih.gov/pmc/articles/PMC3463373/