Lipitor is a brand name for the drug atorvastatin, which is a medication used to lower cholesterol levels in the blood. Like all medications, it can cause side effects, which can vary in severity from person to person.

According to the NHS [2], common side effects of atorvastatin include headache, nausea, diarrhea, and constipation. These side effects are usually mild and go away on their own. However, some people may experience more severe side effects such as muscle pain, weakness, and tenderness. These symptoms can be a sign of a rare but serious condition called rhabdomyolysis, which can cause kidney damage.

The Mayo Clinic [3] notes that other rare but serious side effects of atorvastatin include liver problems, allergic reactions, and memory loss. It is important to seek medical attention immediately if you experience any of these symptoms.

Drug Patent Watch [1] reports that the most common side effects of atorvastatin are headache, muscle pain, and nausea. They note that while these side effects are usually mild, they can be more severe in some people.

In summary, while atorvastatin (Lipitor) is generally well-tolerated, it can cause side effects ranging from mild to severe. Common side effects include headache, nausea, and muscle pain, while rare but serious side effects include rhabdomyolysis, liver problems, and allergic reactions. If you experience any of these symptoms, it is important to seek medical attention immediately.

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