Naproxen sodium can temporarily reduce pain and lower your fever, but it can have serious gastrointestinal side effects 23. Naproxen is grouped with other nonsteroidal anti-inflammatory drugs called NSAIDs, such as aspirin and ibuprofen 2. Naproxen effectively treats minor aches and pains, especially when taken precisely as prescribed or according to the over-the-counter naproxen label directions 2. If you have on-going stomach problems, such as stomach upset, pain, heartburn or ulcers, consult your physician before starting naproxen 2.

Stomach Pain

Stomach pain associated with taking naproxen sodium may indicate serious life-threatening side effects or a possible overdose 23. A connection exists between taking naproxen and the formation of ulcers in the lining of the stomach, stomach and intestinal bleeding, and perforation of the stomach or intestines, according to Medline Plus 12. These disorders of the gastrointestinal tract may take place with or without warning symptoms while taking naproxen 2. Consult your physician immediately if you experience stomach pain with naproxen 2.

Naproxen Sodium Function

Naproxen sodium, the primary active ingredient in naproxen, is available by prescription and over the counter 23. It acts by reducing levels of the hormones that create the inflammatory and pain process in the body, a normal response to illness or injury. Naproxen is available in a number of forms such as tablets, liquid and suppositories, as well as in extended-release and controlled-release 2. Taking naproxen with food or milk may prevent stomach upset 2.

Side Effects

Common side effects of naproxen sodium include:

• headache
  
• edema
  
• vision problems
  
• constipation
  
• rash
  
• diarrhea
  
• ringing in the ears 23

Taking naproxen for fevers or for its anti-inflammatory properties may actually mask signs and symptoms of a more serious infection 2. Naproxen can affect some blood test results, such as liver enzymes, potassium and kidney function 2. Serious side effects include dizziness, faintness, bloody vomit and bloody, black or tarry stools. These indicate stomach and intestinal bleeding.

Warnings

Unless specifically ordered by your physician, use of naproxen during the last trimester of pregnancy is discouraged 2. It may lead to birth defects as well as complications during delivery. Naproxen passes into breast milk, so Drugs.com recommends that you not take it while nursing 2. Taking more naproxen than prescribed or for longer than prescribed increases the risk of serious cardiovascular problems such as heart attack or stroke 2. Symptoms associated with the heart and circulation include difficulties with vision or balance, breathing problems, weakness, chest pain and slurred speech.