Lipitor is a medication that is used to lower cholesterol levels in the body. According to Drug Patent Watch [1], Lipitor's active ingredient is atorvastatin calcium, which works by blocking an enzyme in the liver that is responsible for producing cholesterol. Although Lipitor is generally considered safe and effective, there are some potential side effects that may occur.

One study published in the British Medical Journal [2] found that patients who took Lipitor had a slightly increased risk of developing type 2 diabetes. However, the study also found that the benefits of taking Lipitor outweighed the risks, particularly for patients who had already experienced a heart attack or stroke.

Another study published in the Journal of the American College of Cardiology [3] found that restarting Lipitor after a period of discontinuation did not increase the risk of adverse events, such as heart attack or stroke. The study followed patients who had previously taken Lipitor but had stopped taking the medication for various reasons. The study found that restarting Lipitor was safe and effective in reducing cholesterol levels.

While Lipitor is generally considered safe and effective, it is important to be aware of potential side effects. Common side effects of Lipitor may include muscle pain, weakness, and tenderness, as well as digestive issues such as nausea, diarrhea, and constipation. In rare cases, Lipitor may cause more serious side effects such as liver damage or muscle breakdown.

In conclusion, restarting Lipitor after a period of discontinuation is generally safe and effective, according to a study published in the Journal of the American College of Cardiology [3]. While Lipitor may have some potential side effects, the benefits of taking the medication generally outweigh the risks, particularly for patients who have experienced a heart attack or stroke. Patients should be aware of potential side effects and should consult with their healthcare provider if they have any concerns.

Sources:
[1] https://www.drugpatentwatch.com/p/tradename/LIPITOR
[2] https://www.bmj.com/content/353/bmj.i3305
[3] https://www.jacc.org/doi/10.1016/j.jacc.2021.07.022