What are the possible side effects of Naprosyn, Anaprox, and Anaprox DS?

Naprosyn, Anaprox and Anaprox DS may cause serious side effects that require immediate medical attention, including black or bloody stools, blood in your urine or vomit, change in the amount of urine, blurred vision, hearing changes, chest pain, difficulty breathing, wheezing, nausea, vomiting, severe stomach pain, difficulty or pain when swallowing, fast heartbeat, pounding heartbeat, skin rash, skin redness, blistering or peeling skin, mild allergic reactions with hives or itching, easy bruising or bleeding, mental or mood changes, unexplained weight gain or swelling, signs of infection, unexplained stiff neck, persistent or severe headaches, unusual weakness or fatigue, fainting, yellowing of the eyes or skin.

More severe side effects that need immediate medical assistance and the need to call 911 include: a severe allergic reaction with swelling of the eyelids, throat or lips with difficulty breathing; or other severe symptoms such as slurred speech or weakness on one side of the body.

Other less serious side effects may include: dizziness, diarrhea, headaches, tiredness, drowsiness, upset stomach, nausea and heartburn. Your doctor can suggest ways to relieve these minor side effects.