Naproxen 500 mg is a prescription-strength anti-inflammatory medication used to treat pain, swelling, and stiffness from conditions like arthritis, gout flare-ups, tendinitis, bursitis, and menstrual cramps. It belongs to the class of drugs called NSAIDs (nonsteroidal anti-inflammatory drugs) and is stronger than the over-the-counter version you’d find as Aleve, which contains 220 mg of naproxen sodium per tablet.
What Naproxen 500 mg Treats
The 500 mg strength is typically prescribed for conditions that cause ongoing or intense inflammation. Osteoarthritis and rheumatoid arthritis are among the most common reasons people take it long-term, since it reduces the joint swelling and stiffness that make daily movement difficult. It’s also prescribed for ankylosing spondylitis, a type of arthritis that primarily affects the spine.
For short-term use, naproxen 500 mg is effective against acute gout attacks, where a joint (often the big toe) becomes intensely swollen and painful within hours. It’s also commonly prescribed for menstrual cramps, tendinitis, bursitis, and general musculoskeletal pain like back strains or post-surgical discomfort. The prescription strength delivers roughly twice the active ingredient of an OTC dose, which is why it’s reserved for pain that lower doses can’t adequately control.
How It Works in Your Body
When tissue is injured or inflamed, your body produces chemicals called prostaglandins that amplify pain signals and trigger swelling. Naproxen blocks the enzymes responsible for making those prostaglandins. By reducing prostaglandin levels at the site of inflammation, it lowers pain, swelling, and heat in the affected area. It’s a nonselective blocker, meaning it affects both major forms of the enzyme involved, which is why it’s effective across such a wide range of inflammatory conditions but also why it can irritate the stomach lining.
How Quickly It Works
You can expect to feel some pain relief within about an hour of taking a dose. That said, if you’re taking naproxen on a regular schedule (typically twice a day for a chronic condition), it can take up to three days of consistent use before you feel its full effect. This is because the drug needs time to build up in your system and steadily suppress inflammation rather than just masking a single episode of pain.
A single dose lasts roughly 8 to 12 hours, which is noticeably longer than ibuprofen. That longer duration is one of the main reasons prescribers choose naproxen for conditions requiring all-day coverage with fewer pills.
Prescription 500 mg vs. OTC Naproxen
Over-the-counter naproxen sodium (sold as Aleve) comes in 220 mg tablets, and the recommended OTC dose caps out at two tablets in a 12-hour period. Prescription naproxen 500 mg delivers a significantly higher dose per tablet, which is why it requires a prescription. The chemical forms differ slightly too: the OTC version uses naproxen sodium, which dissolves and absorbs a bit faster, while the prescription tablet is naproxen base. In practice, both deliver the same active compound once absorbed. The real difference is potency per dose and the medical oversight that comes with the higher strength.
Cardiovascular Safety Compared to Other NSAIDs
All NSAIDs carry some cardiovascular risk, but naproxen stands out as the safest option in this category. A large meta-analysis of 138 randomized trials found that high-dose ibuprofen and several other NSAIDs were associated with a roughly 40 to 60 percent increased risk of heart attacks and other vascular events. High-dose naproxen showed no such increase. The American College of Cardiology has noted that naproxen appears to have the least harmful cardiovascular risk profile, including in people with a history of heart attack or heart failure. If you have heart disease or risk factors for it, this distinction matters.
Common Side Effects
The most frequent side effects are digestive: stomach pain, heartburn, nausea, constipation, gas, and bloating. These happen because the same prostaglandins naproxen suppresses also help protect the stomach lining. Other common effects include headache, dizziness, drowsiness, and occasionally difficulty sleeping. Some people notice ringing in the ears or excessive thirst. These side effects are generally mild and often improve as your body adjusts to the medication.
Stomach and Kidney Risks
The most serious concern with naproxen, especially at the 500 mg strength, is gastrointestinal damage. NSAIDs can cause ulcers, bleeding, or even perforations in the stomach or intestinal wall. These problems can develop at any point during treatment and sometimes appear without warning symptoms. The risk is higher if you’re over 60, have a history of stomach ulcers, smoke, drink alcohol regularly, or take blood thinners or steroid medications at the same time.
Warning signs of GI bleeding include stomach pain, heartburn that doesn’t go away, vomit that looks bloody or like coffee grounds, and black or tarry stools. Any of these warrant immediate medical attention.
Naproxen can also affect the kidneys. Signs of kidney trouble include a noticeable decrease in how much or how often you urinate, swelling in the feet, ankles, or face, unexplained weight gain, cloudy or bloody urine, and lower back pain. The kidneys rely on prostaglandins to regulate blood flow, so blocking those chemicals can reduce kidney function, particularly in people who are already dehydrated, elderly, or taking blood pressure medications.
Who Should Be Cautious
Certain people face higher risks with naproxen 500 mg. If you’ve ever had a stomach ulcer or GI bleeding, this medication can reactivate those problems. People taking blood thinners face a compounded bleeding risk because naproxen itself has mild blood-thinning properties. Combining it with steroid medications also increases the chance of stomach damage significantly.
If you take medication for high blood pressure, be aware that naproxen can reduce the effectiveness of those drugs and cause your body to retain fluid. This can lead to swelling in the legs, ankles, or abdomen and may worsen blood pressure control. People with existing kidney disease should use naproxen cautiously, as it can further strain kidney function and lead to dangerously high potassium levels in the blood.
Taking naproxen with alcohol is a particularly risky combination. Alcohol irritates the stomach lining on its own, and pairing it with an NSAID multiplies the chance of developing an ulcer or bleeding episode.