Which of the following medications is most commonly used for pain relief?

Ibuprofen is commonly used for pain relief due to its classification as a nonsteroidal anti-inflammatory drug (NSAID). It works by inhibiting the production of certain chemicals in the body known as prostaglandins, which play a key role in causing inflammation, pain, and fever. As a result, ibuprofen effectively reduces pain ranging from mild headaches to more severe pain conditions, and it also helps to reduce inflammation in various situations.

In contrast, the other medications listed serve different therapeutic purposes. Warfarin is an anticoagulant used to prevent blood clots; its primary role is related to cardiovascular issues rather than pain management. Lisinopril is an antihypertensive that treats high blood pressure and heart failure, focusing on cardiovascular health. Levothyroxine is a thyroid hormone replacement used to manage hypothyroidism, addressing hormone deficiencies rather than pain.

The specific function of ibuprofen as an analgesic and anti-inflammatory is what categorizes it as the most common choice for pain relief among the options provided.