Lipitor (atorvastatin) is a medication used to lower cholesterol levels in the blood, while blood thinners, such as warfarin and heparin, are used to prevent blood clots. According to the sources provided, there is no specific recommendation on how often Lipitor and blood thinners should be taken together, as this depends on the individual patient's condition and medical history.

It is important to note that while atorvastatin is not a blood thinner, it can increase the risk of bleeding when taken with blood thinners [3]. Therefore, patients taking both medications should be closely monitored by their healthcare provider for any signs of bleeding or bruising.

The NHS notes that patients taking atorvastatin should have their liver function checked before starting the medication and regularly thereafter, as the drug can affect liver function [2]. Additionally, patients taking blood thinners should have their blood clotting time monitored regularly to ensure that the medication is working effectively and not causing excessive bleeding [2].

In summary, there is no set frequency for taking Lipitor and blood thinners together, as this will depend on the individual patient's condition and medical history. Patients taking both medications should be closely monitored by their healthcare provider for any signs of bleeding or liver function changes.

Sources:
[1] https://www.drugpatentwatch.com/p/tradename/LIPITOR
[2] https://www.nhs.uk/conditions/statins/considerations/
[3] https://www.singlecare.com/blog/is-atorvastatin-a-blood-thinner/