Lipitor is a brand name for the drug atorvastatin, which is a medication used to lower cholesterol levels in the blood [3]. According to the sources provided, there is no evidence to suggest that Lipitor affects the effectiveness of birth control pills [2][3]. However, it is always important to consult with a healthcare provider to discuss any potential drug interactions when taking multiple medications [2].

It is worth noting that Lipitor may interact with other medications such as antibiotics, antifungals, and immunosuppressants, which could affect the metabolism of Lipitor in the body [1][2]. This could lead to an increased risk of side effects or decreased effectiveness of the medication [2].

In conclusion, there is no evidence to suggest that Lipitor affects the effectiveness of birth control pills. However, it is important to consult with a healthcare provider to discuss any potential drug interactions when taking multiple medications.

Sources:
[1] Drug Patent Watch. (n.d.). Lipitor. Retrieved from https://www.drugpatentwatch.com/p/tradename/LIPITOR
[2] GoodRx. (2021). Atorvastatin: Interactions. Retrieved from https://www.goodrx.com/atorvastatin/interactions
[3] NHS. (2019). Atorvastatin. Retrieved from https://www.nhs.uk/medicines/atorvastatin/common-questions-about-atorvastatin/