Naproxen belongs to a class of drugs called nonsteroidal anti-inflammatory drugs (NSAIDs). Other members of this class include ibuprofen (Motrin), indomethacin (Indocin), nabumetone (Relafen) and several others. These drugs are used for the management of mild to moderate pain, fever, and inflammation. They work by reducing the levels of prostaglandins, chemicals that are responsible for pain, fever, and inflammation. Naproxen blocks the enzyme that makes prostaglandins (cyclooxygenase), resulting in lower concentrations of prostaglandins. As a consequence, inflammation, pain and fever are reduced. Naproxen was approved by the FDA in December 1991.

Naproxen is used for the treatment of mild to moderate pain, inflammation, and fever.

The most common side effects from naproxen are:

• rash,
• ringing in the ears,
• headaches,
• dizziness,
• drowsiness, abdominal pain, nausea,
• diarrhea,
• constipation,
• heartburn,
• fluid retention, and
• shortness of breath.

Other important side effects include:

• fluid retention,
• blood clots,
• heart attacks,
• hypertension, and
• heart failure.

The usual adult dose for pain is 250 every 6 to 8 hours or 500 mg twice daily using regular naproxen tablets. The usual dose for Naprelan controlled release tablets is 750 to 1000 mg given once daily. For EC-Naprosyn, the usual dose is 375-500 mg twice daily.

Naproxen should be given with food to reduce upset stomach. The dose for rheumatoid arthritis, osteoarthritis, or ankylosing spondylitis is 500 to 1000 mg every 12 hours. Dysmenorrhea is treated with 250 mg every 6 to 8 hours after an initial dose of 500 mg.

Naproxen is associated with several suspected or probable interactions that affect the action of other drugs. The following examples are the most common suspected interactions.

• Naproxen may increase the blood levels of lithium (Eskalith, Lithobid) by reducing the excretion of lithium by the kidneys. Increased levels of lithium may lead to lithium toxicity.
• Naproxen may reduce the blood pressure lowering effects of blood pressure medications. This may occur because prostaglandins play a role in the regulation of blood pressure.
• When naproxen is used in combination with methotrexate (Rheumatrex, Trexall) or aminoglycosides (for example, gentamicin) the blood levels of the methotrexate or aminoglycoside may increase, presumably because the elimination from the body of these drugs is reduced. This may lead to more methotrexate or aminoglycoside-related side effects.
• Individuals taking anticoagulants, for example, warfarin, (Coumadin), should avoid naproxen because naproxen also thins the blood, and excessive blood thinning may lead to bleeding.
• Naproxen increases the negative effect of cyclosporine on kidney function and reduces the effect of furosemide (Lasix) and thiazide diuretics because of prostaglandin inhibition.
• Naproxen should be avoided by patients with a history of asthma attacks, hives or other allergic reactions to aspirin or other NSAIDs. If aspirin is taken with naproxen there may be an increased risk for developing an ulcer.
• Persons who have more than 3 alcoholic beverages per day may be at increased risk of developing stomach ulcers when taking naproxen or other NSAIDs.

NSAIDs may cause a fetal birth defect called ductus arteriosus (early closure of two major blood vessels of the heart and lung) in the third trimester of pregnancy. Therefore, NSAIDs should be avoided during this last part of pregnancy.

A small amount of naproxen is excreted in breast milk. Because the concentration in breast milk is low, breastfeeding while taking naproxen probably is not harmful to the infant.

Preparations

• Anaprox (tablets): 275 and 550 mg
• Naprosyn (tablets): 250, 375 and 500 mg
• Naprosyn suspension: 125 mg/5ml
• EC-Naprosyn: 375 mg
• Aleve: 220 mg
• Naprelan (controlled-release tablets): 375 and 500 mg.

Storage

Naproxen should be stored at room temperature: 15 C to 30 C (59 F to 86 F).

Brand names

Anaprox, Naprelan, Naprosyn, Aleve, Mediproxen are the brand names available for naproxen in the US.

Prescription or nonprescription

Aleve is available over-the-counter (OTC, without a prescription), but the other brand names require a prescription from a doctor or other healthcare professional.