Advil and antacids are two different types of medications that serve different purposes. Advil is a nonsteroidal anti-inflammatory drug (NSAID) used to relieve pain and reduce fever, while antacids are used to neutralize stomach acid and relieve heartburn.

According to the sources provided, there is no specific time frame that must be observed between taking Advil and antacids. However, it is generally recommended to space out the two medications to avoid any potential interactions.

One study published in the Journal of Clinical Pharmacology [2] found that taking an antacid with ibuprofen (the active ingredient in Advil) did not significantly affect the absorption of the drug. However, the study did note that taking an antacid with aspirin (another NSAID) did result in a decrease in absorption.

Another source [3] suggests that taking antacids with Advil may increase the risk of gastrointestinal side effects such as stomach ulcers and bleeding. Therefore, it is important to consult with a healthcare provider before taking these medications together.

In conclusion, while there is no specific time frame that must be observed between taking Advil and antacids, it is generally recommended to space out the two medications to avoid any potential interactions. It is also important to consult with a healthcare provider before taking these medications together, especially if you have a history of gastrointestinal issues or are taking other medications.

Sources:
[2] https://pubmed.ncbi.nlm.nih.gov/18280125/
[3] https://greengablespa.com/is-it-safe-to-take-antacid-with-ibuprofen/