Lipitor, also known as Atorvastatin, is a medication that is commonly prescribed to treat high cholesterol levels in the blood. While the medication is effective in reducing cholesterol levels, it may also cause certain side effects. According to the sources provided, the following are some of the common side effects of Lipitor:

1. Headaches - According to the NHS [2], headaches are a common side effect of Lipitor. This side effect is usually mild and goes away on its own.

2. Muscle pain and weakness - Lipitor can cause muscle pain and weakness, which can be a sign of a more serious condition called rhabdomyolysis. The risk of this side effect is higher in people who are taking high doses of the medication or who have kidney problems [2][3].

3. Nausea and stomach pain - Lipitor can cause gastrointestinal side effects such as nausea, stomach pain, and diarrhea [2][3].

4. Liver problems - In rare cases, Lipitor can cause liver problems, including liver damage and liver failure. Symptoms of liver problems may include yellowing of the skin or eyes, dark urine, and abdominal pain [2][3].

5. Memory problems - According to the Mayo Clinic [3], some people who take Lipitor may experience memory problems or confusion. This side effect is usually mild and goes away once the medication is stopped.

It is important to note that not everyone who takes Lipitor will experience these side effects. If you are taking Lipitor and experience any of these side effects, you should contact your healthcare provider immediately. Your healthcare provider may adjust your dosage or switch you to a different medication to help manage your symptoms.

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