Lipitor is a brand name for the drug atorvastatin, which is used to lower cholesterol levels and reduce the risk of heart disease. According to the sources provided, Lipitor can cause several side effects.

The first source, Drug Patent Watch [1], lists the possible side effects of Lipitor as including headache, nausea, diarrhea, muscle and joint pain, and increased blood sugar levels. It also notes that some people may experience more serious side effects, such as liver damage or muscle breakdown.

The second source, NHS [2], states that common side effects of atorvastatin include headache, aches and pains, and stomach problems. It also notes that more serious side effects, such as liver problems, are rare.

The third source, Drugwatch [3], lists muscle pain and weakness as the most common side effects of Lipitor. It also notes that some people may experience more serious side effects, such as liver problems, memory loss, and an increased risk of diabetes.

It is important to note that not everyone who takes Lipitor will experience side effects, and the severity of side effects can vary from person to person. If you experience any side effects while taking Lipitor, you should speak to your doctor or pharmacist.

Sources:
[1] https://www.drugpatentwatch.com/p/tradename/LIPITOR
[2] https://www.nhs.uk/medicines/atorvastatin/side-effects-of-atorvastatin/
[3] https://www.drugwatch.com/lipitor/side-effects/