Naproxen 500mg is a prescription-strength anti-inflammatory painkiller used to treat conditions like arthritis, tendinitis, bursitis, menstrual cramps, and general pain. It belongs to a class of drugs called NSAIDs (nonsteroidal anti-inflammatory drugs), the same family as ibuprofen, but naproxen lasts significantly longer in your body, providing up to 12 hours of pain relief from a single dose.
How Naproxen Works
Your body produces substances called prostaglandins whenever tissue is damaged or inflamed. These prostaglandins trigger pain, swelling, and heat at the site of injury. Naproxen works by blocking the enzymes (COX-1 and COX-2) that produce prostaglandins, physically preventing the raw materials from reaching the enzyme’s active site. With fewer prostaglandins circulating, inflammation drops and pain eases.
This same mechanism explains why naproxen can irritate the stomach. Prostaglandins also help maintain the protective lining of your digestive tract, so blocking them reduces that protection as a side effect.
How It Compares to Ibuprofen
The most practical difference between naproxen and ibuprofen is how long each one works. In a clinical trial comparing the two after oral surgery, naproxen provided meaningful pain relief for 8 to 12 hours, while ibuprofen’s effect dropped off sooner. The median time before patients needed additional pain medication was 7 hours with naproxen versus 6 hours with ibuprofen. From hours 8 through 12, naproxen was statistically better at controlling pain.
This is why ibuprofen is typically taken every 4 to 6 hours, while naproxen is taken every 12 hours. If you find yourself constantly re-dosing ibuprofen, naproxen’s longer duration can be a real advantage, especially overnight.
Prescription vs. Over-the-Counter
You can buy naproxen over the counter under the brand name Aleve, but those tablets contain 220mg of naproxen sodium, which is equivalent to about 200mg of naproxen. The 500mg prescription strength is roughly 2.5 times the OTC dose. Other prescription brand names include Naprosyn, Anaprox-DS, EC-Naprosyn, and Naprelan.
The 500mg tablet is the most commonly prescribed strength for moderate to severe pain, arthritis, and inflammatory conditions. For pain management, the typical starting dose is 1,000mg (two 500mg tablets) on the first day, then 500mg every 12 hours. The maximum daily dose varies by condition but generally should not exceed 1,000 to 1,500mg per day.
How Quickly It Works
The standard naproxen 500mg tablet reaches peak levels in your bloodstream within about 2 to 4 hours. Delayed-release versions take longer, reaching peak levels in 4 to 6 hours (sometimes up to 12). Naproxen has a notably long half-life of 12 to 17 hours, meaning it stays active in your system much longer than most other over-the-counter painkillers. This is what allows twice-daily dosing instead of the every-few-hours schedule that ibuprofen requires.
Common Side Effects
Most people tolerate naproxen well at standard doses, but digestive complaints are the most frequent issue. These include gas, constipation, and general stomach discomfort. Taking it with food or a full glass of water can help reduce irritation.
Other common side effects include headache, dizziness, drowsiness, excessive thirst, difficulty sleeping, and ringing in the ears. These tend to be mild and often improve as your body adjusts.
Serious Risks to Know About
All NSAIDs, including naproxen, carry two important warnings. The first involves your cardiovascular system: long-term or high-dose use may increase the risk of heart attack or stroke. This risk exists even in people with no prior heart problems, though it’s higher with longer use and larger doses.
The second involves your digestive tract. NSAIDs can cause ulcers, bleeding, or perforations anywhere from the esophagus to the intestines. These complications can develop without warning symptoms. The risk increases with age, higher doses, longer duration of use, smoking, and heavy alcohol consumption.
For older adults, both of these risks deserve extra attention. Elderly patients are more sensitive to naproxen’s effects on the kidneys and stomach, and lower doses are generally recommended.
Who Should Avoid Naproxen
Pregnant women should not take naproxen at 20 weeks of pregnancy or later. The FDA issued this warning because NSAIDs used after 20 weeks can impair fetal kidney function and reduce amniotic fluid levels. After 30 weeks, there’s an additional risk of a critical blood vessel in the baby’s heart closing prematurely.
People with significant kidney or liver disease need adjusted doses or may need to avoid naproxen entirely, since the drug is processed through both organs. If you take blood thinners like warfarin, blood pressure medications, or diuretics (water pills), naproxen can interact with all of these. It can amplify the blood-thinning effect of anticoagulants, raise blood pressure, and reduce the effectiveness of diuretics.
Tips for Taking It Safely
Take naproxen with food or a full glass of water to protect your stomach lining. Don’t lie down for at least 10 minutes after swallowing the tablet. If you’re using it for a short-term issue like a sprain or menstrual cramps, keep the dose as low as possible for the shortest time that works. For chronic conditions like arthritis, your prescriber will weigh the benefits of ongoing use against the cumulative risks.
Avoid combining naproxen with other NSAIDs, including OTC ibuprofen or aspirin taken for pain relief. Stacking these drugs doesn’t improve results but does multiply the risk of stomach bleeding and kidney problems. If you drink alcohol regularly, that further raises the chance of GI complications.