Advil is a brand name for ibuprofen, a nonsteroidal anti-inflammatory drug (NSAID) that is commonly used to relieve pain, inflammation, and fever. According to sources [2] and [3], Advil can cause stomach irritation, which is a common side effect of NSAIDs. Stomach irritation can range from mild discomfort to serious complications such as bleeding and ulcers. To reduce the risk of stomach irritation, it is recommended to take Advil with food or milk, avoid alcohol and smoking, and not to exceed the recommended dose. Additionally, people with a history of stomach ulcers, gastrointestinal bleeding, or kidney problems should consult their doctor before taking Advil or any other NSAID. According to source [1], Advil has been on the market since 1984 and is currently available in various forms, including tablets, capsules, and liquid gels. It is important to note that while Advil is a popular and effective pain reliever, it is not suitable for everyone and can cause side effects. Therefore, it is essential to follow the recommended dosage and consult a healthcare professional if you experience any adverse effects.

Sources:
[1] https://www.drugpatentwatch.com/p/tradename/ADVIL
[2] https://www.hss.edu/conditions_guidelines-reduce-side-effects-nsaids.asp
[3] https://www.goodrx.com/advil/advil-side-effects