Lipitor is a medication used to treat high cholesterol and reduce the risk of heart attack and stroke. According to the sources provided, rare side effects of Lipitor can occur, but the frequency of these side effects is not clearly defined.

The first source, Drug Patent Watch [1], provides information on the patent status of Lipitor and its generic equivalents. However, it does not provide any information on the frequency of rare side effects.

The second source, Medical News Today [2], lists a range of possible side effects of Lipitor, including rare side effects such as muscle pain, liver problems, and allergic reactions. However, the article does not provide specific information on the frequency of these rare side effects.

The third source, Mayo Clinic [3], also lists a range of possible side effects of Lipitor, including rare side effects such as muscle damage, liver problems, and memory loss. The article notes that these side effects are rare but can be serious. However, again, there is no specific information on the frequency of these rare side effects.

In summary, while rare side effects of Lipitor can occur, the frequency of these side effects is not clearly defined in the sources provided. Patients should be aware of the possible side effects of Lipitor and discuss any concerns with their healthcare provider.

Sources:
[1] https://www.drugpatentwatch.com/p/tradename/LIPITOR
[2] https://www.medicalnewstoday.com/articles/drugs-lipitor-side-effects
[3] https://www.mayoclinic.org/drugs-supplements/atorvastatin-oral-route/side-effects/drg-20067003