Based on the information available, it typically takes 2-4 weeks for Lipitor (atorvastatin) to show its cholesterol-lowering effects [1]. However, individual results may vary, and it's essential to continue taking the medication as prescribed by a healthcare professional.

Lipitor belongs to a class of drugs called statins, which work by blocking the enzyme in the liver responsible for producing cholesterol. By reducing the amount of cholesterol produced, Lipitor helps lower the levels of "bad" LDL cholesterol and triglycerides in the blood, thereby reducing the risk of heart disease and stroke [2].

It's important to note that Lipitor may not show its full cholesterol-lowering effects until after several weeks of use. Regular blood tests are necessary to monitor cholesterol levels and ensure that the medication is working effectively.

In summary, it takes 2-4 weeks for Lipitor to show its cholesterol-lowering effects, and individual results may vary. Regular monitoring of cholesterol levels is essential to ensure the medication's effectiveness.

Sources:
[1] <https://www.drugs.com/answers/how-long-does-it-take-for-lipitor-to-lower-cholesterol-695231.html>
[2] <https://www.drugpatentwatch.com/drugs/lipitor>