Aspirin and Advil are both nonsteroidal anti-inflammatory drugs (NSAIDs) that are used to treat pain, fever, and inflammation. However, they have different active ingredients and can cause different side effects.

Aspirin, also known as acetylsalicylic acid, works by blocking the production of prostaglandins, which are responsible for causing pain, inflammation, and fever. It is commonly used to treat headaches, menstrual cramps, and mild to moderate pain. Aspirin is also used to prevent blood clots and reduce the risk of heart attack and stroke [1].

The most common side effect of aspirin is stomach irritation, which can lead to ulcers and bleeding. Aspirin can also cause ringing in the ears, dizziness, and allergic reactions in some people. Long-term use of aspirin can increase the risk of bleeding and kidney damage [2].

Advil, also known as ibuprofen, works by reducing the production of prostaglandins. It is commonly used to treat headaches, menstrual cramps, and mild to moderate pain. Advil is also used to reduce fever and inflammation [3].

The most common side effect of Advil is stomach irritation, which can lead to ulcers and bleeding. Advil can also cause headaches, dizziness, and allergic reactions in some people. Long-term use of Advil can increase the risk of kidney damage and heart attack [2].

In summary, both aspirin and Advil can cause stomach irritation and bleeding, but aspirin is more likely to cause these side effects. Aspirin is also more likely to cause ringing in the ears and allergic reactions. Advil is more likely to cause headaches and increase the risk of heart attack. It is important to talk to a doctor or pharmacist before taking any medication, especially if you have a history of stomach ulcers, kidney disease, or heart disease [2, 3].

Sources:
[1] https://www.drugpatentwatch.com/p/tradename/ASPIRIN
[2] https://www.healthline.com/health/aspirin-vs-ibuprofen
[3] https://blog.walgreens.com/health/pain-management/acetaminophen-vs-aspirin-vs-ibuprofen.html