Aspirin is a common over-the-counter medication used to treat pain, reduce inflammation, and lower fever. It belongs to a group of medications known as nonsteroidal anti-inflammatory drugs (NSAIDs). Aspirin works by inhibiting an enzyme called cyclooxygenase, which is involved in the production of prostaglandins, chemicals in the body that cause pain, inflammation, and fever. It is commonly used to treat conditions such as headaches, muscle aches, arthritis, and fevers. In addition to its pain-relieving properties, aspirin is also used in low doses to prevent heart attacks and strokes in people at high risk for these conditions.