NSAID Risks and Boxed Warnings: Ibuprofen, Naproxen, Diclofenac and More

Short answer: NSAIDs such as ibuprofen, naproxen, diclofenac and celecoxib are effective medicines for pain, inflammation and fever, but they are not harmless. Important risks include gastrointestinal bleeding and ulcers, kidney injury, fluid retention, higher blood pressure and cardiovascular events. The safest principle is generally to use the lowest effective dose for the shortest necessary duration, while taking individual risk factors into account.

The older version of this article made NSAIDs sound as if they simply “mute” a useful warning signal and disable the body’s ability to respond to injury. That is not how their benefit-risk balance should be understood. Pain relief can be medically useful; the question is whether the expected benefit outweighs the drug’s known risks for a particular person.

What is an NSAID?

NSAID stands for nonsteroidal anti-inflammatory drug. Common examples include ibuprofen, naproxen, diclofenac, celecoxib and aspirin.

Acetaminophen (paracetamol, Tylenol) is a pain reliever and fever reducer, but it is not an NSAID. It has a different risk profile, including a major concern about liver injury when too much is taken or when multiple acetaminophen-containing products are combined.

NSAIDs inhibit cyclooxygenase enzymes involved in prostaglandin production. Prostaglandins participate in pain and inflammation, but also help regulate gastric protection, kidney blood flow, platelets and vascular function. That helps explain both why NSAIDs work and why side effects occur.

What does the FDA boxed warning actually mean?

Prescription non-aspirin NSAIDs carry prominent warnings about serious cardiovascular and gastrointestinal risks. FDA labeling warns that NSAIDs can increase the risk of heart attack and stroke, and can cause gastrointestinal bleeding, ulceration and perforation, sometimes without warning and sometimes fatally.

Risk can begin early in treatment and tends to increase with higher doses and longer use. A person’s absolute risk is also influenced by age, previous ulcer or bleeding, cardiovascular disease, kidney disease, other medicines and other health conditions.

Over-the-counter NSAIDs also carry safety warnings, although the packaging and regulatory format are not identical to the boxed warnings used for prescription products.

NSAIDs and heart attack or stroke

FDA strengthened cardiovascular warnings for non-aspirin NSAIDs after reviewing randomized and observational evidence. The increased cardiovascular risk is not limited to people who already have heart disease, although people with cardiovascular disease or risk factors have a higher absolute risk because their baseline risk is higher.

There is no good basis for calling diclofenac simply “the strongest NSAID.” Different NSAIDs differ in potency, duration, COX selectivity, formulation and safety profile. The clinically relevant question is not which one is strongest, but which drug, dose and duration best match the condition and the patient’s risk.

NSAIDs are generally avoided around coronary artery bypass graft surgery, and use after a recent myocardial infarction requires particular caution and medical guidance.

NSAIDs and stomach bleeding

Prostaglandins help protect the gastrointestinal lining. Reducing prostaglandin synthesis can increase susceptibility to ulcers and bleeding.

The risk is not a fixed percentage that applies to everyone. It varies substantially with age, dose, duration, previous ulcer or GI bleeding, alcohol use and concurrent medicines such as anticoagulants, antiplatelet drugs, corticosteroids and some antidepressants.

Warning signs that require prompt medical assessment include black or tarry stool, vomiting blood or material resembling coffee grounds, fainting, or severe persistent abdominal pain.

NSAIDs and the kidneys

NSAIDs can reduce prostaglandin-mediated blood flow within the kidneys. For many healthy people using a short course this does not cause clinically important kidney injury, but risk rises in people who are dehydrated, older, have chronic kidney disease, heart failure or liver disease, or take certain combinations of blood-pressure medicines and diuretics.

NSAIDs can also promote sodium and fluid retention and may raise blood pressure or worsen edema and heart failure in susceptible people.

Are NSAIDs bad because they block pain?

No. Pain is not always a signal that should simply be left untreated so the body can “respond correctly.” Severe or persistent pain can impair movement, sleep, rehabilitation and quality of life.

The real concern is different: pain relief can sometimes make it easier to continue an activity that is aggravating an injury, or can temporarily mask symptoms that deserve diagnosis. That is a reason to identify the cause of persistent or unexplained pain, not a reason to conclude that pain relief itself is physiologically harmful.

Can you combine different NSAIDs?

Taking two systemic NSAIDs together, for example ibuprofen plus naproxen, usually increases toxicity without providing a proportional additional benefit and should generally be avoided unless specifically directed by a clinician.

Many cold, flu, headache and sleep products contain an NSAID, so accidental duplication is possible. Reading the active-ingredient section of the label matters more than the brand name.

What about aspirin?

Aspirin is an NSAID, but low-dose aspirin used for cardiovascular prevention is a special case because its irreversible antiplatelet effect is often the reason it is prescribed.

Other NSAIDs can sometimes interfere with aspirin’s antiplatelet action, and combining aspirin with another NSAID can raise bleeding risk. A person taking prescribed low-dose aspirin should not casually add or stop NSAIDs without checking the combination.

NSAIDs during pregnancy

Pregnancy deserves a separate warning.

FDA advises avoiding NSAIDs at about 20 weeks of pregnancy or later unless specifically recommended by a healthcare professional because they can cause fetal kidney dysfunction and low amniotic fluid. From around 30 weeks, NSAIDs can also cause premature closure of the fetal ductus arteriosus.

An important exception is low-dose 81 mg aspirin when it is specifically prescribed for certain pregnancy-related indications.

FDA: NSAIDs in pregnancy at 20 weeks or later.

NSAIDs vs acetaminophen

Acetaminophen can relieve pain and fever but has little anti-inflammatory effect at usual doses. It avoids some NSAID-related gastrointestinal, platelet and kidney effects, but it has its own major hazard: excessive dosing can cause severe liver injury.

FDA lists a maximum recommended adult total of 4,000 mg of acetaminophen per day from all medicines combined, but individual products and clinicians may recommend lower limits depending on the person and situation.

FDA: Don’t Overuse Acetaminophen.

Who should be especially cautious with NSAIDs?

Extra caution is warranted in people with a history of stomach ulcer or GI bleeding, cardiovascular disease, heart failure, chronic kidney disease, uncontrolled hypertension, dehydration, anticoagulant or antiplatelet treatment, and during pregnancy. Age and other medications also change risk.

This does not mean every person in these groups can never receive an NSAID. It means the benefit-risk calculation and sometimes the choice of alternative treatment deserve more attention.

How to reduce risk

The broad FDA principle is sensible: use the lowest effective dose for the shortest duration necessary.

Also avoid accidental duplication, check drug interactions, stay within the product label unless a clinician directs otherwise, and do not use an NSAID to repeatedly suppress unexplained pain without investigating the cause.

Bottom line

NSAIDs are neither harmless everyday pills nor drugs that should be feared simply because they suppress pain and inflammation.

They are useful medicines with well-characterized dose- and patient-dependent risks.

Established major risks include: cardiovascular events, gastrointestinal bleeding and ulcers, kidney injury and fluid retention.

Acetaminophen is not an NSAID. It has a different risk profile, especially liver toxicity with excessive total dosing.

Risk is not identical for every NSAID or every person. Drug choice, dose, duration, age, medical history and concurrent medications all matter.

Sources

1. U.S. Food and Drug Administration. Safe Use of Over-the-Counter Pain Relievers and Fever Reducers.

2. FDA. Avoid Use of NSAIDs in Pregnancy at 20 Weeks or Later.

3. FDA. Don’t Overuse Acetaminophen.