Lipitor is a brand name for the drug atorvastatin, which is used to lower cholesterol levels in the body. Like all medications, Lipitor can cause side effects. According to the National Health Service (NHS) [2], the most common side effects of Lipitor are headache, feeling sick, diarrhea, constipation, and muscle and joint pain. These side effects usually go away on their own after a few days or weeks of taking the medication. However, some people may experience more serious side effects.

One of the more serious side effects of Lipitor is muscle pain or weakness. This can be a sign of a rare but serious condition called rhabdomyolysis [2]. Rhabdomyolysis is a breakdown of muscle tissue that can lead to kidney damage or failure. If you experience severe muscle pain or weakness while taking Lipitor, you should contact your doctor immediately.

Other rare but serious side effects of Lipitor include liver problems, allergic reactions, and an increased risk of diabetes [3]. If you experience any of these side effects, you should seek medical attention right away.

It is important to note that not everyone who takes Lipitor will experience side effects. In fact, most people tolerate the medication well [1]. However, if you do experience side effects, it is important to talk to your doctor about your options.

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/