Breathing difficulties are not listed as a common side effect of Lipitor, a medication used to lower cholesterol levels. Lipitor's primary side effects typically involve muscle pain, weakness, and liver problems. Pulmonary hypertension, a condition characterized by high blood pressure in the arteries of the lungs, can cause breathing difficulties. However, there is no direct link between Lipitor and pulmonary hypertension mentioned in the sources provided. It is advisable to consult a healthcare professional for personalized medical advice regarding any concerns about breathing difficulties during yoga while taking Lipitor.

Sources:
[1] https://www.drugpatentwatch.com/p/tradename/LIPITOR
[2] https://my.clevelandclinic.org/health/diseases/6530-pulmonary-hypertension-ph
[3] https://www.medicalnewstoday.com/articles/lipitor