Naproxen 500 mg is a prescription-strength anti-inflammatory tablet used to treat pain, swelling, and stiffness from conditions like arthritis, gout, tendinitis, and menstrual cramps. It belongs to a class of drugs called NSAIDs (nonsteroidal anti-inflammatory drugs), the same family as ibuprofen. The 500 mg dose is one of the higher strengths available, typically taken twice a day, and it provides up to 12 hours of pain relief per dose.
How Naproxen Works
Your body produces enzymes called COX-1 and COX-2 that help create chemicals involved in inflammation, pain, and fever. Naproxen blocks both of these enzymes, which reduces swelling and lowers pain signals. It does this by physically blocking the spot where the inflammation-triggering process begins, preventing the chain reaction that leads to redness, heat, and soreness at an injury or disease site.
Naproxen is considered a nonselective NSAID, meaning it blocks both COX enzymes rather than targeting just one. This broad action makes it effective for a wide range of pain types but also explains some of its side effects, particularly on the stomach, since COX-1 plays a role in protecting the stomach lining.
What It’s Prescribed For
The FDA has approved naproxen for a specific list of conditions:
- Rheumatoid arthritis and osteoarthritis: ongoing joint inflammation and pain
- Ankylosing spondylitis: inflammatory arthritis of the spine
- Tendinitis and bursitis: inflammation of tendons or the fluid-filled sacs near joints
- Acute gout: sudden, severe joint inflammation from uric acid crystals
- Menstrual cramps
- Mild to moderate pain: headaches, dental pain, muscle aches, and similar
For chronic conditions like arthritis, naproxen is often taken daily on a schedule. For acute problems like a gout flare or menstrual cramps, it’s typically used for a shorter period until the pain resolves.
How Long It Takes to Work
Pain relief from naproxen tablets begins within about 1 hour. The sodium form (naproxen sodium, sold as Aleve over the counter) absorbs slightly faster and can start working within 30 minutes. Either way, the effect lasts up to 12 hours, which is why naproxen is usually taken just twice daily rather than every 4 to 6 hours like ibuprofen. That longer duration is one of the main practical advantages of naproxen over shorter-acting NSAIDs.
Dosing and Daily Limits
A typical prescription dose for arthritis is one 500 mg tablet twice a day, for a total of 1,000 mg. For more severe arthritis symptoms, a prescriber may increase the total to 1,500 mg per day, which is generally the maximum. For shorter-term issues like tendinitis, bursitis, or menstrual cramps, the daily ceiling is usually lower, around 1,000 mg per day.
Taking naproxen with food or a full glass of water can help reduce stomach irritation. If you’re using a controlled-release or delayed-release version, the tablet should be swallowed whole rather than crushed or chewed, since the coating controls how the drug is absorbed.
Common Side Effects
The most frequent side effects are gastrointestinal: nausea, heartburn, stomach pain, constipation, diarrhea, and gas. These are common across all NSAIDs because blocking COX-1 reduces the protective mucus layer in your stomach. Most people tolerate naproxen fine at standard doses for short periods, but the risk of stomach problems increases with higher doses and longer use.
More serious GI complications, including stomach ulcers, bleeding, or perforation, can develop at any point during treatment and 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.
Some people also notice swelling in the ankles, feet, or legs. Naproxen can cause the body to retain fluid and may affect kidney function, particularly in people who are already dehydrated or have existing kidney issues. Decreased urination, cloudy urine, or unusual thirst can signal kidney-related effects.
Cardiovascular Risk
All NSAIDs other than aspirin carry a warning about increased risk of heart attack and stroke. However, naproxen appears to have a somewhat more favorable cardiovascular profile compared to other common NSAIDs. A large Danish study covering over 7.6 million NSAID users found that people starting ibuprofen had an 18% higher rate of major vascular events (heart attack or stroke) compared to those starting naproxen. The difference was most pronounced for ischemic stroke, where ibuprofen users had a 28% higher rate.
This doesn’t mean naproxen is free of cardiovascular risk, but it is one reason prescribers sometimes prefer it for patients who need long-term NSAID therapy, particularly those with some cardiovascular concern.
Who Should Not Take Naproxen
Naproxen is not safe for everyone. You should avoid it entirely if you:
- Have had an allergic reaction to aspirin or any NSAID, especially one involving hives, facial swelling, asthma attacks, or difficulty breathing
- Are about to have or recently had coronary artery bypass surgery (CABG)
- Have experienced a serious skin reaction to an NSAID in the past
- Have aspirin-sensitive asthma, particularly if you also have nasal polyps
People with a history of stomach ulcers, kidney disease, or liver problems need careful evaluation before using naproxen, since the drug can worsen all three conditions.
Drug Interactions to Know About
Naproxen interacts with several commonly used medications. Blood thinners are the most important: taking naproxen alongside an anticoagulant significantly raises the risk of bleeding, especially in the stomach and intestines. Naproxen can also increase blood levels of lithium, a medication used for bipolar disorder, potentially pushing it into a toxic range. And if you take blood pressure medication, naproxen may reduce its effectiveness by causing your body to retain sodium and fluid, which works against what those drugs are trying to do.
Combining naproxen with other NSAIDs, including over-the-counter ibuprofen or aspirin, increases the chance of stomach bleeding without adding much extra pain relief. If you’re already taking prescription naproxen, avoid stacking additional NSAIDs on top of it.