According to Drugs.com, there is a moderate interaction between doxycycline and Lipitor (atorvastatin) [2]. Taking these medications together can increase the risk of liver damage and muscle injury. Therefore, it is recommended to monitor liver function tests and muscle symptoms if taking these medications together. Additionally, it is important to inform your healthcare provider if you experience any unusual symptoms or side effects while taking these medications together.

However, the severity of the interaction may vary depending on the individual and their medical history. A study published in the Journal of Pharmacy Practice found that there is a potential for drug-drug interactions between doxycycline and statins, including Lipitor [3]. The study suggests that healthcare providers should be aware of this potential interaction and monitor patients accordingly.

In summary, taking doxycycline while on Lipitor can increase the risk of liver damage and muscle injury. It is recommended to monitor liver function tests and muscle symptoms if taking these medications together. It is important to inform your healthcare provider if you experience any unusual symptoms or side effects while taking these medications together. Healthcare providers should be aware of this potential interaction and monitor patients accordingly.

Sources:
[2] https://www.drugs.com/drug-interactions/doxycycline-with-lipitor-940-0-276-128.html
[3] https://pubmed.ncbi.nlm.nih.gov/30203771/