Aleve (naproxen sodium) carries real risks that go beyond what most people expect from an over-the-counter painkiller. It can damage your stomach lining, raise your blood pressure, strain your kidneys, and slightly increase your chance of a heart attack, even at recommended doses. The FDA requires a boxed warning on all NSAIDs, including Aleve, for serious cardiovascular and gastrointestinal events. None of this means you can never take it, but understanding the risks helps you use it more carefully.
How Aleve Damages Your Stomach
Aleve belongs to a class of drugs called NSAIDs (nonsteroidal anti-inflammatory drugs), and the same mechanism that reduces pain and inflammation also strips away your stomach’s built-in protection. Your stomach lining constantly produces a layer of mucus and bicarbonate to shield itself from its own acid. That production depends on compounds called prostaglandins. Aleve blocks the enzyme responsible for making those prostaglandins, so your stomach produces more acid while simultaneously losing its protective barrier.
The damage happens through two routes. First, naproxen is a weak acid itself. When it enters your stomach, it can slip directly into the cells lining your stomach wall, disrupting their membranes and triggering cell death. Second, the body-wide suppression of prostaglandins reduces blood flow to the stomach lining and slows the repair of any damage that occurs. Together, these effects can lead to erosions, ulcers, and bleeding. The FDA warning states plainly that these gastrointestinal events “can occur at any time during use and without warning symptoms.” Older adults and anyone with a history of stomach ulcers face the highest risk.
The Effect on Your Kidneys
Your kidneys rely on prostaglandins to keep blood flowing through them, especially when your body is under stress from dehydration, illness, or certain medications. Under normal conditions, this prostaglandin support is a backup system you barely need. But when your kidney blood flow is already compromised, those prostaglandins become essential. Aleve shuts down their production, which can cause a noticeable drop in kidney function.
In one study of healthy older adults, naproxen lowered the kidney filtration rate after just a single dose. For people already at risk, the consequences can be more serious, including sudden kidney failure. You’re most vulnerable if you’re over 65 (when kidney function naturally declines), if you take diuretics (water pills), or if you have heart failure, liver cirrhosis, or chronic kidney disease. Even in otherwise healthy people, long-term daily use puts extra strain on the kidneys that adds up over time.
Heart Attack and Stroke Risk
Aleve has long been considered one of the safer NSAIDs for the heart, but “safer” is relative. A large meta-analysis published in The BMJ found that taking naproxen for just one to seven days raised the odds of a heart attack by about 53% compared to not taking any NSAID. Ibuprofen carried a similar increase of about 48%. These are relative increases on top of a small baseline risk, so the absolute danger for a healthy person is still low, but it’s not zero.
The risk can begin early in treatment and grows with longer use. The FDA’s required boxed warning for all NSAIDs states they “cause an increased risk of serious cardiovascular thrombotic events, including myocardial infarction and stroke, which can be fatal.” People with existing heart disease or risk factors like high blood pressure, high cholesterol, or diabetes carry a higher baseline risk, making even a modest percentage increase more meaningful.
Blood Pressure Effects
Aleve raises blood pressure. Studies show naproxen increases mean arterial pressure by roughly 3.7 mm Hg. That might sound small, but for someone already managing hypertension, it can be enough to push readings out of a controlled range. Worse, Aleve can blunt the effectiveness of common blood pressure medications, including ACE inhibitors, ARBs, beta-blockers, and diuretics. If you take one of these drugs and add Aleve for a sore back or headache, your blood pressure medication may quietly stop working as well as it should.
Dangerous Drug Combinations
Aleve interacts with several widely prescribed medications in ways that compound its risks:
- Blood thinners (warfarin and similar drugs): Aleve increases the risk of bleeding on its own. Combined with anticoagulants, that risk multiplies significantly.
- Blood pressure medications: As noted above, Aleve can reduce the effectiveness of ACE inhibitors, ARBs, beta-blockers, and diuretics. In elderly or dehydrated patients already on these drugs, the combination can also accelerate kidney damage.
- SSRIs and SNRIs (common antidepressants): These medications also affect clotting, and pairing them with Aleve increases bleeding risk.
- Other NSAIDs or aspirin: Stacking Aleve with ibuprofen or aspirin doesn’t double the benefit but does multiply the stomach and bleeding risks.
Breathing Problems in Some People
A condition called aspirin-exacerbated respiratory disease (AERD) affects people who react to aspirin and other NSAIDs, including naproxen. It’s not a true allergy but rather an abnormal chemical response that produces high levels of compounds called leukotrienes, which tighten the airways. Symptoms can come on suddenly and include wheezing, severe nasal congestion, coughing, and difficulty breathing that mimics a serious asthma attack. If you’ve ever had a breathing reaction to aspirin or ibuprofen, Aleve poses the same danger.
Who Faces the Most Risk
Aleve is not equally risky for everyone. The people most likely to experience serious side effects include those over 65, anyone with a history of stomach ulcers or GI bleeding, people with heart failure or cardiovascular disease, those with impaired kidney function, and anyone taking blood thinners or blood pressure medications. The NHS lists severe heart failure as a condition that makes naproxen unsuitable entirely.
Age alone is a significant factor because it affects nearly every system Aleve can harm. Older adults have thinner stomach linings, reduced kidney filtration, higher baseline cardiovascular risk, and are more likely to be on interacting medications. What feels like a harmless pain reliever at 30 carries meaningfully different stakes at 70.
OTC Dosing Limits and Why They Matter
The FDA-approved over-the-counter label for Aleve caps use at three caplets (660 mg of naproxen sodium) in 24 hours, and the label advises stopping after 10 days for pain or 3 days for fever unless a doctor says otherwise. These limits exist because the risks described above are dose-dependent and duration-dependent. Higher doses and longer use increase the likelihood of stomach damage, kidney problems, and cardiovascular events.
Many people exceed these limits without realizing it, either by taking extra pills when pain persists or by using Aleve daily for weeks or months for chronic conditions like arthritis. Prescription-strength naproxen goes higher than the OTC dose, but it comes with medical monitoring. Using OTC Aleve at higher doses or for longer durations means absorbing prescription-level risk without any of the oversight.