Lipitor is a brand name for the drug atorvastatin, which is a type of medication called a statin that is used to lower cholesterol levels in the blood. According to Drug Patent Watch [1], there are no known withdrawal effects when stopping the use of Lipitor or atorvastatin. However, abruptly stopping the use of statins is not recommended as it can lead to adverse health outcomes [2].

Stopping statins can increase the risk of heart attack and stroke, especially for those who have already had a heart attack or stroke [2]. Statins help to prevent the buildup of plaque in the arteries, which can lead to heart disease. When statins are stopped, the plaque buildup can resume, increasing the risk of cardiovascular events [2].

Additionally, stopping statins can lead to a rebound effect, where cholesterol levels rise quickly and to higher levels than before starting the medication [2]. This can lead to an increased risk of heart disease and stroke.

According to a study reported by CNN [3], there are also potential side effects associated with taking statins, including muscle pain, liver damage, and an increased risk of developing type 2 diabetes. However, the benefits of taking statins, such as reducing the risk of heart attack and stroke, outweigh the risks for most people.

In conclusion, there are no known withdrawal effects when stopping the use of Lipitor or atorvastatin. However, abruptly stopping statins is not recommended as it can increase the risk of heart attack and stroke. It is important to discuss any concerns about stopping statins with a healthcare provider.

Sources:
[1] https://www.drugpatentwatch.com/p/tradename/LIPITOR
[2] https://www.goodrx.com/classes/statins/stopping-statins-eight-reasons-you-should-not-stop-your-cholesterol-drug
[3] https://www.cnn.com/2017/07/24/health/statins-side-effects-outcomes-study/index.html