Lipitor is a brand name for the drug atorvastatin, which is used to lower cholesterol levels in the body. According to Drug Patent Watch [1], the most common side effects of Lipitor are muscle pain, diarrhea, and joint pain. On the other hand, Vitamin D is essential for bone health, and its deficiency can cause various health problems. A study published in the QJM: An International Journal of Medicine [3] suggests that Vitamin D deficiency is common in patients taking statins like Lipitor. However, the study did not find any significant side effects of combining Lipitor and Vitamin D. Another study published in PubMed [2] also suggests that Vitamin D supplementation can help reduce the risk of muscle pain associated with statin use.

In conclusion, while Lipitor can cause some side effects such as muscle pain and diarrhea, there is no evidence to suggest that combining Lipitor and Vitamin D causes any significant side effects. In fact, Vitamin D supplementation may even help reduce the risk of muscle pain associated with Lipitor use. However, it is always advisable to consult a healthcare professional before taking any new medication or supplement.

Sources:
[1] https://www.drugpatentwatch.com/p/tradename/LIPITOR
[2] https://pubmed.ncbi.nlm.nih.gov/18754003/
[3] https://academic.oup.com/qjmed/article/105/5/487/1565780