Lipitor is a medication used to treat high cholesterol levels in the blood. It is a statin drug that works by blocking the enzyme responsible for producing cholesterol in the liver. While Lipitor is generally safe and well-tolerated, it can cause side effects when combined with certain medications.

According to Drug Patent Watch [1], there are several drugs that can interact with Lipitor and increase the risk of side effects. These include antibiotics such as erythromycin and clarithromycin, antifungal drugs such as ketoconazole and itraconazole, and HIV medications such as ritonavir and saquinavir. When taken with Lipitor, these drugs can increase the levels of Lipitor in the blood, leading to a higher risk of side effects such as muscle pain and liver damage.

A study published in the National Center for Biotechnology Information [2] found that the combination of Lipitor and amlodipine, a medication used to treat high blood pressure, can cause muscle pain and weakness. The study also found that the combination of Lipitor and fenofibrate, another medication used to treat high cholesterol, can increase the risk of liver damage.

Medical News Today [3] reports that Lipitor can also interact with grapefruit juice, which can increase the levels of Lipitor in the blood and increase the risk of side effects. Patients taking Lipitor should avoid consuming grapefruit juice or any other grapefruit products.

In conclusion, while Lipitor is generally safe and well-tolerated, it can cause side effects when combined with certain medications. Patients taking Lipitor should talk to their doctor or pharmacist before taking any new medications or supplements to avoid potential interactions. They should also avoid consuming grapefruit products while taking Lipitor.

Sources:
[1] https://www.drugpatentwatch.com/p/tradename/LIPITOR
[2] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5438352/
[3] https://www.medicalnewstoday.com/articles/lipitor