Aleve (naproxen sodium, 220 mg per tablet) is one of the most widely used over-the-counter pain relievers, but it carries a real set of side effects worth knowing about. The most common are digestive issues like stomach pain, heartburn, and nausea. More serious risks involve the stomach lining, kidneys, and cardiovascular system, especially with higher doses or long-term use. The maximum OTC dose is three tablets in 24 hours.
How Aleve Works (and Why It Causes Side Effects)
Aleve belongs to the NSAID class of drugs. It reduces pain, fever, and inflammation by blocking enzymes your body uses to produce prostaglandins, chemical messengers that trigger swelling and pain at injury sites. The problem is that these same prostaglandins also protect your stomach lining, support blood flow to your kidneys, and help regulate blood clotting. Aleve is a nonselective NSAID, meaning it blocks both the inflammation-related enzyme and the protective one with roughly equal strength. That’s why its side effects tend to cluster around the gut, kidneys, and cardiovascular system.
Common, Mild Side Effects
Most people who take Aleve occasionally at recommended doses tolerate it well. But even short-term use can produce noticeable effects. The most frequently reported include:
- Stomach discomfort: heartburn, nausea, gas, or constipation
- Headache or dizziness
- Drowsiness or trouble sleeping
- Excessive thirst
- Ringing in the ears
- Tingling or burning sensations in the arms or legs
These side effects are typically mild and go away once you stop taking the drug. Taking Aleve with food or a full glass of water can reduce stomach irritation for many people.
Stomach Ulcers and GI Bleeding
The most well-known serious risk of any NSAID, including Aleve, is damage to the gastrointestinal tract. By suppressing the prostaglandins that maintain your stomach’s protective mucus layer, naproxen leaves the lining vulnerable to acid. Over time, or at higher doses, this can lead to ulcers or bleeding in the stomach or intestines.
What makes GI bleeding particularly dangerous is that it can happen without obvious warning signs. Sometimes the first clue is a black, tarry stool, which indicates blood that’s been digested as it passed through the intestinal tract. Severe abdominal pain or visible blood in your stool are clear signals to stop the medication immediately and contact a doctor.
Certain groups face higher risk. Older adults are more vulnerable to GI complications from NSAIDs. People with a prior history of peptic ulcers or GI bleeding are at significantly greater risk as well. Taking Aleve alongside aspirin further increases the chance of developing an ulcer, because both drugs suppress the same protective stomach mechanisms through slightly different pathways.
Kidney Effects
Your kidneys rely on prostaglandins to maintain healthy blood flow, especially when you’re dehydrated, under physical stress, or already have reduced kidney function. By blocking prostaglandin production, Aleve can reduce blood flow to the kidneys and impair their ability to filter waste. Even in people with healthy kidneys, taking high doses for extended periods can cause kidney damage.
The risk is more immediate for people who already have reduced kidney function, heart disease, or high blood pressure. For these groups, the National Kidney Foundation recommends avoiding NSAIDs unless a doctor has specifically approved their use. Signs of kidney trouble from Aleve include swelling in the ankles or feet, unusual fatigue, or a noticeable decrease in how often you urinate.
Cardiovascular Risks
All NSAIDs carry some degree of cardiovascular risk. Long-term use or high doses can increase the likelihood of heart attack and stroke. This risk exists even in people without prior heart problems, though it’s higher in those who already have cardiovascular disease. The risk tends to increase the longer you take the medication and the higher the dose.
Naproxen has generally been considered to carry a somewhat lower cardiovascular risk compared to some other NSAIDs, but “lower” does not mean zero. If you’re taking Aleve regularly for a chronic condition, the cardiovascular trade-off is worth discussing with a healthcare provider.
Allergic and Severe Reactions
True allergic reactions to naproxen are uncommon but can be serious. Symptoms range from hives and skin rash to a full anaphylactic reaction involving low blood pressure, weakness, difficulty breathing, and swelling of the face or throat. These reactions typically develop quickly after taking the drug.
People with asthma face a specific concern. A subset of asthma patients are sensitive to NSAIDs, and naproxen can trigger bronchospasm, worsening breathing problems. If you have asthma and have never taken Aleve before, it’s worth being cautious with the first dose and aware of any respiratory changes.
Drug Interactions That Raise Risk
Aleve can amplify the effects, or the dangers, of several common medications. The most important interactions involve bleeding risk. If you take a blood thinner like warfarin, adding Aleve on top increases your chance of serious bleeding events, including upper GI tract bleeding and, in rare cases, intracranial hemorrhage.
Certain antidepressants (SSRIs and similar drugs) also carry their own mild blood-thinning effect by reducing platelet activity. Combining these with Aleve creates a compounding bleeding risk that many people don’t realize. If you’re on an antidepressant in this class, check with your pharmacist before using Aleve regularly.
Aleve can also interfere with blood pressure medications by promoting fluid retention, which works against the drugs designed to lower your pressure. And combining it with aspirin, as noted above, raises GI bleeding risk while potentially reducing aspirin’s protective cardiovascular benefits.
Who Should Be Extra Cautious
Several groups need to be particularly careful with Aleve. Older adults face higher risks across the board: more GI complications, more cardiovascular events, and more kidney sensitivity. People with a history of stomach ulcers, kidney disease, heart failure, or high blood pressure should treat Aleve as a medication to use sparingly, if at all. Anyone taking blood thinners or SSRIs should be aware of the compounding bleeding risk.
For occasional use at OTC doses (no more than three 220 mg tablets per day), Aleve is well-tolerated by most healthy adults. The risks climb with higher doses, longer duration, and the presence of other health conditions or interacting medications. The difference between an occasional Aleve for a headache and daily Aleve for chronic back pain represents a meaningful jump in risk profile.