Lipitor is a medication used to lower cholesterol levels in the body and reduce the risk of heart disease and stroke. According to the sources provided, it can take anywhere from a few weeks to several months for Lipitor to work effectively.

The drug patent watch [1] states that Lipitor can take 2-4 weeks to start showing significant results in lowering cholesterol levels. However, it may take up to 4-6 weeks for the full effects of the medication to be seen. The British Heart Foundation [2] supports this claim, stating that it may take several weeks for cholesterol levels to improve after starting Lipitor.

Healthline [3] explains that the dosage and severity of the condition being treated can also affect how long it takes for Lipitor to work. For example, a higher dosage may produce more immediate results, while a lower dosage may take longer to show significant improvement. Additionally, if the patient has very high cholesterol levels, it may take longer for the medication to work effectively.

In summary, Lipitor can take anywhere from a few weeks to several months to work effectively, depending on the dosage, severity of the condition being treated, and the patient's cholesterol levels. It is important to follow the prescribed dosage and continue taking the medication as directed by a healthcare provider to achieve the best results.

Sources:
[1] https://www.drugpatentwatch.com/p/tradename/LIPITOR
[2] https://www.bhf.org.uk/informationsupport/heart-matters-magazine/medical/drug-cabinet/statins
[3] https://www.healthline.com/health/drugs/lipitor