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 considered safe when taken as directed, it can cause side effects in some people. According to the Mayo Clinic [3], common side effects of ibuprofen include stomach pain, nausea, vomiting, constipation, diarrhea, gas, heartburn, and bloating. In some cases, ibuprofen can also cause more serious side effects such as stomach ulcers, bleeding, kidney damage, and liver damage. These serious side effects are more likely to occur in people who take high doses of ibuprofen or who take it for a long time. It is important to follow the dosing instructions on the label and to talk to a healthcare provider before taking Advil or any other medication.

GoodRx [2] also lists some other possible side effects of Advil, including dizziness, headache, ringing in the ears, blurred vision, and skin rash. These side effects are less common but should still be reported to a healthcare provider if they occur.

DrugPatentWatch [1] notes that Advil is available in different forms, including tablets, capsules, and liquid, and that the side effects may vary depending on the form of the medication. It is important to read the label and follow the instructions for the specific form of Advil being taken.

In summary, Advil can cause side effects in some people, ranging from mild to more serious. Common side effects include stomach pain, nausea, and heartburn, while more serious side effects can include stomach ulcers, bleeding, kidney damage, and liver damage. It is important to follow the dosing instructions on the label and to talk to a healthcare provider before taking Advil or any other medication. If any side effects occur, they should be reported to a healthcare provider.

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