Lipitor, also known as atorvastatin, is a medication used to lower cholesterol levels in the body. According to Drug Patent Watch [1], Lipitor is one of the most commonly prescribed medications in the United States. However, one of the possible side effects of taking Lipitor is muscle weakness.

The Mayo Clinic [2] states that muscle weakness is a rare side effect of taking statins, including Lipitor. The muscle weakness can range from mild discomfort to severe muscle damage, which can lead to kidney failure. The risk of muscle weakness increases when Lipitor is taken with certain medications or when the dosage is increased. Therefore, it is important to talk to a healthcare provider before taking Lipitor.

A study published in the US National Library of Medicine [3] examined the effects of atorvastatin on muscle function in patients with high cholesterol. The study found that while atorvastatin did not significantly decrease muscle strength, it did lead to a decrease in muscle endurance. The study also noted that the decrease in muscle endurance was reversible once the medication was discontinued.

In conclusion, Lipitor, or atorvastatin, can cause muscle weakness as a rare side effect. It is important to talk to a healthcare provider before taking Lipitor, especially if taking other medications or if the dosage is increased. While atorvastatin did not significantly decrease muscle strength, it did lead to a decrease in muscle endurance, which was reversible once the medication was discontinued.

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/PMC2949584/