Lipitor (atorvastatin) is a medication used to lower cholesterol levels and reduce the risk of heart attack and stroke. While it is generally well-tolerated, like any medication, it can cause side effects. Some of the more common side effects of Lipitor include headache, muscle aches, joint pain, diarrhea, and constipation [2]. However, there are also some rare side effects that can occur, including:

1. Liver problems: Lipitor can cause liver damage, which can be serious and potentially life-threatening. Symptoms of liver problems include yellowing of the skin or eyes, dark urine, and abdominal pain [2].

2. Allergic reactions: In rare cases, Lipitor can cause an allergic reaction. Symptoms of an allergic reaction include hives, difficulty breathing, and swelling of the face, lips, tongue, or throat [3].

3. Muscle problems: Lipitor can cause muscle damage, which can lead to a condition called rhabdomyolysis. Symptoms of muscle problems include muscle pain, weakness, and tenderness [2].

4. Neurological problems: Lipitor can cause neurological problems, including memory loss, confusion, and depression [1].

5. Blood sugar problems: Lipitor can cause an increase in blood sugar levels, which can lead to diabetes [2].

It is important to note that these side effects are rare and that Lipitor is generally considered safe and effective. However, if you experience any of these symptoms while taking Lipitor, you should contact your doctor immediately. They may need to adjust your dosage or switch you to a different medication.

Sources:
[1] https://www.drugpatentwatch.com/p/tradename/LIPITOR
[2] https://www.mayoclinic.org/drugs-supplements/atorvastatin-oral-route/side-effects/drg-20067003
[3] https://www.webmd.com/drugs/2/drug-3330/lipitor-oral/details/list-sideeffects