There is limited information on the potential interaction between Advil (ibuprofen) and doxycycline. Advil is a nonsteroidal anti-inflammatory drug (NSAID) that is commonly used to relieve pain and inflammation. Doxycycline is an antibiotic used to treat bacterial infections.

According to Drug Patent Watch [1], there are no known drug interactions between Advil and doxycycline. However, it is important to note that this does not necessarily mean that no interaction exists.

The NHS [2] lists some common side effects of doxycycline, including stomach pain, diarrhea, and indigestion. Advil can also cause stomach problems such as ulcers and bleeding. Therefore, taking Advil and doxycycline together may increase the risk of stomach issues.

A study published in the journal Clinical Pharmacology and Therapeutics [3] found that taking ibuprofen with doxycycline did not significantly affect the effectiveness of doxycycline in treating a bacterial infection. However, the study was conducted on a small sample size and only tested a single dose of ibuprofen.

In conclusion, while there is no known interaction between Advil and doxycycline, taking these two medications together may increase the risk of stomach problems. It is recommended to consult with a healthcare provider before taking these medications together.

Sources:
[1] https://www.drugpatentwatch.com/p/tradename/ADVIL
[2] https://www.nhs.uk/medicines/doxycycline/side-effects-of-doxycycline/
[3] https://pubmed.ncbi.nlm.nih.gov/9706854/