Advil is a brand name for ibuprofen, which is a nonsteroidal anti-inflammatory drug (NSAID) used to treat pain, fever, and inflammation. While Advil is generally considered safe and effective, it can cause side effects in some people. According to the Mayo Clinic [3], common side effects of ibuprofen include upset stomach, heartburn, nausea, vomiting, headache, dizziness, and drowsiness. 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 perforation [3]. These side effects are more likely to occur in people who take high doses of Advil or take it for a long time. Other serious side effects of Advil include kidney damage, high blood pressure, and allergic reactions [2]. Symptoms of an allergic reaction to Advil can include hives, rash, itching, swelling of the face or throat, and difficulty breathing.

It is important to talk to a doctor before taking Advil, especially if you have a history of stomach ulcers, bleeding, or other medical conditions. People who are allergic to aspirin or other NSAIDs should also avoid taking Advil. Additionally, people who are pregnant or breastfeeding should talk to a doctor before taking Advil, as it can affect the baby [2].

In summary, while Advil is generally safe and effective, it can cause side effects in some people. Common side effects include upset stomach, heartburn, nausea, vomiting, headache, dizziness, and drowsiness. More serious side effects can include stomach ulcers, bleeding, and perforation, kidney damage, high blood pressure, and allergic reactions. It is important to talk to a doctor before taking Advil, especially if you have a history of medical conditions or are pregnant or breastfeeding.

Sources:
[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