Advil is a brand name for ibuprofen, which is a nonsteroidal anti-inflammatory drug (NSAID) used to relieve pain and reduce inflammation. Although Advil is generally safe when used as directed, it can cause side effects. According to the Mayo Clinic [3], the most common side effects of Advil include stomach pain, nausea, vomiting, and diarrhea. These side effects are usually mild and go away on their own. However, Advil can also cause more serious side effects, such as stomach ulcers, bleeding, and kidney damage. People who take Advil for a long time or in high doses are at higher risk of these side effects. It is important to follow the dosage instructions on the label and not take more than recommended. GoodRx [2] notes that Advil can also cause allergic reactions, such as hives, rash, and swelling of the face, lips, tongue, or throat. If you experience any of these symptoms, you should stop taking Advil and seek medical attention immediately. Additionally, Drug Patent Watch [1] warns that Advil can interact with other medications, such as blood thinners and antidepressants, and may increase the risk of side effects. If you are taking other medications, you should talk to your doctor or pharmacist before taking Advil. In summary, Advil can cause side effects, ranging from mild to serious, and it is important to use it as directed and talk to your doctor if you have any concerns.

Sources:
[1] https://www.drugpatentwatch.com/p/tradename/ADVIL
[2] https://www.goodrx.com/advil/advil-side-effects
[3] https://www.mayoclinic.org/drugs-supplements/ibuprofen-oral-route/side-effects/drg-20070602?p=1