Naproxen sodium may cause a severe allergic reaction, especially in people allergic to aspirin. Symptoms may include: hives, facial swelling, asthma (wheezing), shock, skin reddening, rash, blisters. If an allergic reaction occurs, stop use and seek medical help right away. Stomach bleeding: this product contains an NSAID, which may cause severe stomach bleeding. The chance is higher if you are age 60 or older, have had stomach ulcers or bleeding problems, take a blood thinning (anticoagulant) or steroid drug, take other drugs containing prescription or nonprescription NSAIDs (aspirin, ibuprofen, naproxen or others), have 3 or more alcoholic drinks every day while using this product, take more or for a longer time than directed. Do not use: if you have ever had an allergic reaction to any other pain reliever/fever reducer, right before or after heart surgery. Ask a doctor before use if the stomach bleeding warning applies to you, you have a history of stomach problems, such as heartburn, you have high blood pressure, heart disease, liver cirrhosis or kidney disease, you are taking a diuretic, you have problems or serious side effects from taking pain relievers or fever reducers, you have asthma. Ask a doctor or pharmacist before use if you are under a doctor supervision.