Ibuprofen is a commonly used nonsteroidal anti-inflammatory drug (NSAID) that helps relieve pain, reduce inflammation, and lower fever. It works by blocking the production of certain natural substances in the body that cause swelling and discomfort. Ibuprofen is often used for headaches, muscle aches, arthritis, menstrual cramps, and minor injuries, and is available both over the counter and in stronger prescription forms.