Based on the information available, there is no specific mention of a "flexibility side effect" associated with Lipitor (atorvastatin). Lipitor is a prescription medication used to treat high cholesterol levels and reduce the risk of stroke, heart attack, and other heart complications [1].

Common side effects of Lipitor include headache, muscle and joint pain, upset stomach, and cold-like symptoms [1]. Serious side effects may include liver problems, muscle damage, and increased blood sugar levels [1]. However, flexibility side effects are not listed in the FDA-approved label for Lipitor [2].

It is important to consult with a healthcare provider if experiencing any unusual symptoms while taking Lipitor or any other medication. Self-diagnosis and self-treatment based on information found online can be dangerous and should be avoided.

Sources:

[1] "Lipitor- Atorvastatin Calcium Tablet, Film Coated." DailyMed, National Library of Medicine, drugs.nlm.nih.gov/druginfo/dailymed/druginformation.cfm?setid=0903db5e-6e77-4e1e-8bb6-6e8baaebf0f6.

[2] "Lipitor (Atorvastatin Calcium) Label." U.S. Food and Drug Administration, FDA, www.accessdata.fda.gov/drugsatfda_docs/label/2016/020990s054,021168s015lbl.pdf.

[3] "Lipitor (Atorvastatin) Drug Patent Expiration Dates." DrugPatentWatch, drugpatentwatch.com/drugs/lipitor.