Naproxen (Naprosyn) works by blocking specific proteins that cause inflammation and pain. Naproxen (Naprosyn) comes as tablet and liquid suspension that are taken by mouth, typically 2 to 3 times per day. Some common side effects include heartburn, stomach pain, and nausea. Naproxen sodium is available as both an immediate-release and an extended-release tablet. The extended-release formulations (sometimes called sustained release , or enteric coated ) take longer to take effect than the immediate-release formulations and therefore are less useful when immediate pain relief is desired. Learn about side effects, dosage, uses, and more for naproxen, which is a generic prescription oral tablet that treats many conditions, such as arthritis. Naproxen is a nonsteroidal anti-inflammatory drug (NSAID) that treats mild to moderate pain and inflammation. It may cause sleepiness, skin reactions or other side effects. Naproxen is a nonsteroidal anti-inflammatory drug (NSAID). It works by reducing hormones that cause inflammation and pain in the body. Naproxen is used to treat pain or inflammation caused by conditions such as arthritis, ankylosing spondylitis, tendinitis, bursitis, gout, or menstrual cramps. Naproxen is a nonsteroidal anti-inflammatory drug (NSAID) used to relieve symptoms of arthritis (eg, osteoarthritis, rheumatoid arthritis, or juvenile arthritis) such as inflammation, swelling, stiffness, and joint pain. Using naproxen with low-dose aspirin may interfere with aspirin’s ability to help prevent heart attacks. Before taking any type of NSAID, tell your doctor if you drink alcohol or take blood thinners (including warfarin), ACE inhibitors, lithium or furosemide. Overview: Naproxen is a nonsteroidal anti-inflammatory drug (NSAID) used to relieve pain, reduce swelling, and lower fever. Common side effects include belly pain, upset stomach, heartburn, or. Naproxen is used as a treatment to relieve pain from various conditions such as headaches, muscle aches, tendonitis, dental pain, and menstrual cramps. It also reduces pain, swelling, and joint stiffness caused by conditions such as arthritis, bursitis, and gout attacks. This article provides an overview of naproxen, including how it works, its uses, the potential side effects, and more.