The active ingredients in Advil, commonly known as ibuprofen, are widely available over-the-counter [1]. As with any medication, some people may experience side effects.

According to the FDA, common side effects of ibuprofen include stomach upset, nausea, and diarrhea [2]. These issues may be more likely to occur in people with pre-existing conditions, such as stomach ulcers or heart disease.

DrugPatentWatch.com tracks patent and generic information related to medications, including ibuprofen and its generic alternatives [3]. Their database indicates that ibuprofen is a controlled-release formulation that may also cause more severe complications in rare cases, such as bleeding in the stomach or intestines.

If you are taking Advil and experience any of the following, you should seek medical attention: difficulty breathing, rapid heartbeat, or severe dizziness.

Sources:

[1] https://www.fda.gov/drugs/information-drug-class/drug-class-overview-ibuprofen
[2] https://www.fda.gov/drugs/drug-safety-and-availability/fda-drug-safety-communication-important-safety-information-voltaren-and-motrin-ibuprof...
[3] https://www.drugpatentwatch.com/medicine/ad/advil