Advil is a brand name for the generic drug ibuprofen, which is a nonsteroidal anti-inflammatory drug (NSAID) used to relieve pain and reduce fever. According to the official Advil website [2], it is recommended to take Advil with food or milk to help prevent stomach upset. This is because ibuprofen can irritate the lining of the stomach, which can lead to ulcers or bleeding, especially if taken for a long time or in high doses. Taking Advil with food or milk can help to protect the stomach and reduce the risk of these side effects.

However, the website Drugs.com [3] notes that ibuprofen can be taken on an empty stomach if necessary, but it is generally recommended to take it with food or milk. The reason for this is that food can help to slow down the absorption of ibuprofen into the bloodstream, which can reduce the risk of side effects and increase the effectiveness of the drug.

In summary, it is generally recommended to take Advil with food or milk to help prevent stomach upset and reduce the risk of side effects. However, ibuprofen can be taken on an empty stomach if necessary, but this may increase the risk of side effects and decrease the effectiveness of the drug. As always, it is important to follow the instructions on the label and consult with a healthcare professional if you have any questions or concerns about taking Advil or any other medication.

Sources:
[2] https://www.advil.com/faqs-en/advil-pain/
[3] https://www.drugs.com/medical-answers/you-ibuprofen-empty-stomach-3572019/