While naproxen is effective in managing pain and inflammation, it can lead to a range of side effects. Common adverse effects include gastrointestinal issues such as nausea, heartburn, and stomach ulcers. More severe gastrointestinal bleeding can occur with prolonged use. Other side effects may include dizziness, headache, rash, and edema. It is important to monitor for any signs of these adverse effects, especially in long-term use.