Before taking this medicine
Naproxen can increase your risk of fatal heart attack or stroke, especially if you use it long term or take high doses, or if you have heart disease. Even people without heart disease or risk factors could have a stroke or heart attack while taking this medicine.
Do not use this medicine just before or after heart bypass surgery (coronary artery bypass graft, or CABG).
Naproxen may also cause stomach or intestinal bleeding, which can be fatal. These conditions can occur without warning while you are using naproxen, especially in older adults.
You should not use naproxen if you are allergic to it, or if you have ever had an asthma attack or severe allergic reaction after taking aspirin or an NSAID.
Ask a doctor or pharmacist if it is safe for you to use this medicine if you have:
- heart disease, high blood pressure, high cholesterol, diabetes, or if you smoke;
- a history of heart attack, stroke, or blood clot;
- a history of stomach ulcers or bleeding;
- asthma;
- liver or kidney disease; or
- fluid retention.
Taking naproxen during the last 3 months of pregnancy may harm the unborn baby. Do not use this medicine without a doctor's advice if you are pregnant.
Naproxen can pass into breast milk and may harm a nursing baby. You should not breast-feed while using this medicine.
Naproxen is not approved for use by anyone younger than 2 years old.
Do not give this medicine to a child without medical advice.
Source
https://www.drugs.com/naproxen.html