Lipitor is a brand name for atorvastatin, which is a medication used to treat high cholesterol levels. As with any medication, there are potential side effects that patients should be aware of. According to the Mayo Clinic [2], some of the most common side effects of atorvastatin include:

1. Headache
2. Muscle aches and pains
3. Diarrhea
4. Constipation
5. Nausea
6. Stomach pain
7. Skin rash

In rare cases, atorvastatin can cause more serious side effects. These can include liver problems, muscle damage, and an increased risk of diabetes. Patients should seek medical attention immediately if they experience any of the following symptoms while taking atorvastatin [2]:

1. Unexplained muscle pain, tenderness, or weakness
2. Yellowing of the skin or eyes
3. Dark-colored urine
4. Unusual tiredness or weakness
5. Nausea or vomiting
6. Abdominal pain
7. Loss of appetite

It is important for patients to talk to their doctor about any potential side effects of atorvastatin before starting the medication. Patients should also inform their doctor of any other medications they are taking, as some drugs can interact with atorvastatin and increase the risk of side effects [3].

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.nhs.uk/medicines/atorvastatin/side-effects-of-atorvastatin/