Naproxen sodium is a pain reliever and anti-inflammatory drug that works by blocking the enzymes responsible for producing prostaglandins, the chemicals your body makes in response to injury or illness that cause pain, swelling, and fever. It’s available over the counter (as Aleve) and in stronger prescription forms, and a single dose can provide relief lasting up to 12 hours.
How It Reduces Pain and Inflammation
Your body contains two enzymes called COX-1 and COX-2. When you’re injured or sick, these enzymes convert a fatty acid in your cells into prostaglandins, which trigger inflammation, amplify pain signals, and raise your body temperature. Naproxen sodium enters the active site of both enzymes and blocks this conversion, reducing the amount of prostaglandins your body produces.
What makes naproxen unusual compared to some other pain relievers in its class is the way it binds to these enzymes. Rather than locking on tightly and permanently, it acts as a slow, reversible inhibitor, particularly with COX-2. This “mixed” inhibition means it reduces enzyme activity without fully shutting it down, which contributes to its relatively long-lasting but moderate effect.
What People Use It For
Naproxen sodium treats a wide range of pain and inflammatory conditions. Over-the-counter versions are commonly used for headaches, muscle aches, menstrual cramps, toothaches, backaches, and minor arthritis pain. Prescription-strength naproxen is used for more persistent conditions like rheumatoid arthritis, osteoarthritis, ankylosing spondylitis (a type of spinal arthritis), gout attacks, bursitis, and tendinitis.
Because it reduces both pain and inflammation rather than just masking discomfort, it’s particularly effective for conditions where swelling drives the problem. Menstrual cramps are a good example: prostaglandins cause the uterus to contract, and blocking their production at the source often works better than a pain reliever that only dulls the sensation.
How Fast It Works and How Long It Lasts
The “sodium” in naproxen sodium matters here. The sodium salt form dissolves and absorbs faster than plain naproxen (sold as Naprosyn). Pain relief from naproxen sodium can begin within 30 minutes, while the base form of naproxen typically takes closer to an hour. Plasma levels peak within 1 to 2 hours after taking naproxen sodium.
One of naproxen’s biggest practical advantages is its duration. A single dose provides pain relief for up to 12 hours, which is why most people only need to take it twice a day. Extended-release prescription versions are designed to maintain steady blood levels over a full 24 hours, allowing once-daily dosing for chronic conditions.
How It Compares to Ibuprofen
Naproxen and ibuprofen belong to the same drug class, but they behave differently in your body. Ibuprofen is short-acting, with doses needed every four to six hours. It kicks in a bit faster and is often better for short bursts of acute pain. Naproxen is the longer-acting option, making it more practical for ongoing conditions like arthritis where you want steady relief without taking pills throughout the day.
The trade-off for that longer duration is a higher risk of gastrointestinal side effects. Because naproxen stays active in your system longer, it has more time to irritate the stomach lining. Research has shown naproxen is more likely than ibuprofen to cause stomach ulcers and stomach bleeding, especially with prolonged use.
OTC vs. Prescription Strength
Over-the-counter naproxen sodium (Aleve) comes in 220 mg tablets, typically taken every 8 to 12 hours. Prescription versions range from 250 mg to 500 mg tablets taken twice daily, with a usual maximum of 1,500 mg per day for conditions like rheumatoid arthritis. The higher prescription doses are intended for managing chronic inflammatory diseases under medical supervision, not occasional aches.
Side Effects and Risks
The most common side effects are digestive: nausea, heartburn, stomach pain, and diarrhea. These tend to be mild and are more likely when taking naproxen on an empty stomach or at higher doses.
The more serious risks involve the stomach and heart. Naproxen can cause ulcers, bleeding, or even holes in the stomach or intestinal lining. These problems can develop at any point during treatment, sometimes without warning symptoms. Signs to watch for include vomit that looks bloody or like coffee grounds, black or tarry stools, or severe stomach pain.
All NSAIDs in this class, naproxen included, carry an FDA boxed warning for increased risk of heart attack and stroke. This risk applies even with short-term use and can begin within the first few weeks of regular use. Higher doses taken for longer periods raise the risk further. People with existing heart disease face the greatest danger, but even those without heart disease are not immune.
Kidney problems are another concern, particularly for older adults or anyone who is dehydrated. Signs of kidney trouble include decreased urination, cloudy or bloody urine, painful urination, or unexplained back pain.
Medications That Interact With Naproxen
Naproxen has a synergistic effect on bleeding when combined with blood thinners like warfarin, meaning the two together significantly increase the chance of serious bleeding compared to either drug alone.
If you take blood pressure medication, naproxen can reduce its effectiveness. This applies to ACE inhibitors, ARBs, and beta-blockers. For people who are older, dehydrated, or already have reduced kidney function, combining naproxen with ACE inhibitors or ARBs can worsen kidney function, sometimes severely. Naproxen also blunts the effect of common diuretics (water pills), which can be a problem for people relying on those medications to manage fluid retention or blood pressure.