Advil is a nonsteroidal anti-inflammatory drug (NSAID) that is commonly used to relieve pain and inflammation. However, when taken with blood thinners, it can increase the risk of bleeding. Blood thinners such as warfarin and aspirin are prescribed to reduce the risk of blood clots, which can lead to heart attacks and strokes.

According to GoodRx [2], it is recommended to avoid taking Advil with blood thinners as it can increase the risk of bleeding. NSAIDs like Advil work by inhibiting the production of prostaglandins, which are chemicals that cause inflammation and pain. However, prostaglandins also play a role in blood clotting, so inhibiting their production can increase the risk of bleeding.

Harvard Health Publishing [3] notes that taking NSAIDs with blood thinners can also reduce the effectiveness of the blood thinner, making it less effective at preventing blood clots. This can increase the risk of heart attacks and strokes. In addition, taking NSAIDs with blood thinners can also cause gastrointestinal bleeding, which can be life-threatening.

Drug Patent Watch [1] notes that Advil has a black box warning, which is the strongest warning issued by the FDA. This warning states that NSAIDs like Advil can increase the risk of heart attack and stroke, especially when taken in high doses or for long periods of time. When taken with blood thinners, this risk may be further increased.

In conclusion, taking Advil with blood thinners can increase the risk of bleeding and reduce the effectiveness of the blood thinner. It is recommended to avoid taking Advil with blood thinners, and to speak with a healthcare provider before taking any new medications while on blood thinners.

Sources:
[1] https://www.drugpatentwatch.com/p/tradename/ADVIL
[2] https://www.goodrx.com/health-topic/heart/otc-drugs-to-avoid-on-blood-thinners
[3] https://www.health.harvard.edu/diseases-and-conditions/bad-mix-blood-thinners-and-nsaids