Lipitor is a brand name for the drug atorvastatin, which is used to lower cholesterol levels in the body. While Lipitor is generally considered safe and effective, there are some potential side effects to be aware of.

According to the NHS [2], some of the most common side effects of atorvastatin include headaches, nausea, diarrhea, constipation, and stomach pain. Additionally, some people may experience muscle pain or weakness, which can be a sign of a rare but serious condition called rhabdomyolysis.

Drugwatch [3] also notes that some people may experience more serious side effects, such as liver damage, kidney problems, or an increased risk of developing type 2 diabetes. These side effects are relatively rare, but they can be serious and require medical attention.

It's important to note that not everyone who takes Lipitor will experience side effects, and the severity and frequency of side effects can vary from person to person. If you experience any unusual symptoms while taking Lipitor, it's important to talk to your doctor right away.

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