Both Tylenol and Advil are over-the-counter pain relievers, but they have different active ingredients and work in different ways. Tylenol contains acetaminophen, while Advil contains ibuprofen. According to Drug Patent Watch [1], Tylenol is a brand name for acetaminophen, which has been available since 1955. Advil, on the other hand, is a brand name for ibuprofen, which was first approved by the FDA in 1974.

Both drugs are effective at relieving pain, but they work differently. Tylenol works by blocking the production of prostaglandins, which are chemicals that cause pain and inflammation. Advil works by reducing the production of prostaglandins and also by blocking the action of an enzyme called cyclooxygenase (COX), which is involved in the production of prostaglandins [2].

As for safety, both drugs can have side effects. According to GoodRx [3], common side effects of Tylenol include nausea, stomach pain, and headache. Taking too much Tylenol can cause liver damage, especially if combined with alcohol. Advil can cause stomach upset, heartburn, and headache. It can also increase the risk of heart attack or stroke, especially if taken for a long time or in high doses.

In general, both Tylenol and Advil are safe when used as directed. However, it's important to follow the recommended dosage and not exceed the maximum daily dose. It's also important to talk to a doctor before taking these drugs if you have any underlying health conditions or are taking other medications.

In conclusion, both Tylenol and Advil are effective pain relievers, but they work in different ways and can have different side effects. It's important to follow the recommended dosage and talk to a doctor before taking these drugs.

Sources:
[1] https://www.drugpatentwatch.com/p/tradename/TYLENOL
[2] https://www.buzzrx.com/blog/tylenol-vs-advil-which-is-better
[3] https://www.goodrx.com/ibuprofen/advil-ibuprofen-vs-tylenol-acetaminophen-side-effects