WebMD explains that naproxen is a non-steroidal anti-inflammatory drug, not a narcotic. It acts to block the body's production of natural chemicals that produce inflammation. Naproxen is used to treat a wide variety of painful inflammatory conditions, such as arthritis and tendonitis.
Drugs.com says that naproxen is very similar to other familiar NSAIDs, such as aspirin and ibuprofen. It has a similar mechanism of action and many of the same side effects.
Naproxen can cause stomach or intestinal bleeding, according to Drugs.com. It can also increase the risk of strokes and heart attacks. Individuals who have had allergic reactions to other NSAIDs, such as aspirin, can also react to naproxen.