Nonsteroidal anti-inflammatory drugs (NSAIDs) are a group of medications used to reduce inflammation, pain, and fever. They’re among the most widely prescribed drugs in the world. You’re probably familiar with the NSAIDs aspirin and ibuprofen.

NSAIDs are available over the counter (OTC) and by prescription. Prescription NSAIDs are stronger in dose than the OTC versions.

First, let’s look at how two types of NSAIDs work to know the kinds of side effects they can have.

NSAIDs work by blocking your body’s production of the chemicals associated with pain and inflammation. NSAIDs block enzymes called cyclooxygenases (COX). There are two forms of COX:

  • COX-1 protects the stomach lining and aids kidney function.
  • COX-2 is produced when joints are injured or inflamed.

Some NSAIDs work to block both forms of COX. These are called nonselective NSAIDs. They include aspirin, ibuprofen, and naproxen. Because they block both forms of COX, they may have the side effect of stomach irritation.

Other, newer NSAIDs only block COX-2. These are called selective NSAIDs. They include celecoxib (Celebrex). They’re thought to be less likely to cause stomach problems.

NSAIDs, like other drugs, have the risk of side effects. Older people and those with some chronic illnesses may have increased risk for side effects from NSAIDs.

Most people tolerate NSAIDs well. Mild side effects may be countered by lowering the NSAID dose, or taking an additional drug to counter the side effect.

Here are some of the possible side effects:

Stomach problems

Stomach problems are the most common side effect of NSAIDs. These include:

  • irritation or pain
  • heartburn
  • gas
  • diarrhea or constipation
  • bleeding and ulcers
  • nausea
  • vomiting

You can lessen stomach side effects by taking NSAIDs with food, milk, or a drug that blocks acid production (antacid).

Drinking alcohol when taking NSAIDs can increase your risk for internal bleeding.

NSAIDs that release nitric oxide are under development. They’re thought to be able to reduce stomach problems.

Heart attack and stroke

Except for aspirin, NSAIDs can increase your risk for high blood pressure, stroke, or heart attack.

In July 2015, the Food and Drug Administration (FDA) strengthened its warning for all NSAIDs except aspirin about the increased risk of heart attack and stroke.

The warning on all NSAID labels notes that the increased risk can occur in the first weeks of NSAID use. The risk may increase if you use NSAIDs longer. There’s also more likely risk at higher doses.

The FDA warning also says this risk occurs whether or not you have other risk factors for heart disease and stroke.

Increased blood pressure

All NSAIDS can increase your blood pressure whether or not you already have high blood pressure (hypertension).

NSAIDs may also reduce the effect of some blood pressure medications.

On average, NSAIDs can increase blood pressure by 5 millimeters of mercury (mmHg).

Kidney problems

The most common NSAID kidney problem is fluid retention, like swollen ankles and feet. Other kidney problems are less common.

A large 2019 study of U.S. Army soldiers using NSAIDs found small but significant increases in the risk of kidney problems. The effects on the kidneys were found to be dependent on dose.

According to the National Kidney Foundation, NSAIDs may cause an increased risk of sudden kidney failure or kidney damage.

The foundation advises that if you already have decreased kidney function, you should avoid NSAIDs.

Allergic reactions

Allergic reactions to NSAIDs are rare.

If you have symptoms of a generalized allergic reaction, seek emergency medical care.

Symptoms include:

  • swollen lips, tongue, or eyes
  • shortness of breath, wheezing
  • difficulty swallowing
  • rash or hives

Bruising or bleeding

NSAIDs can reduce your blood’s ability to clot. This may cause you to bruise more easily. Small cuts may take longer to stop bleeding.

The effect can be serious if you also take blood thinners like warfarin (Coumadin).

Other side effects

Some people may experience:

  • dizziness
  • balance problems
  • trouble concentrating

Fast facts about NSAIDs

Healthline

Consult your doctor if you have any new symptoms when taking NSAIDs. You may need to adjust the dose or switch to another medication.

Red flag symptoms include:

  • allergic reaction, such as itching, rash, or swelling
  • unexplained weight gain
  • black stools
  • blurry vision
  • fatigue
  • sensitivity to light
  • trouble urinating
  • bad headache or other pain
  • pain in the middle of your back

If you have more severe symptoms, get emergency help.

Get urgent help for:
  • trouble breathing
  • chest pain
  • weakness on one part of your body
  • swelling of your face or throat
  • slurred speech

The Cleveland Clinic advises that you not use an OTC NSAID for more than three days for fever and 10 days for pain. When taking an NSAID for a longer time, your doctor should monitor you.

Many medical professional societies recommend using NSAIDs with caution at the lowest effective dose for the shortest possible time.

Long-term use of NSAIDs has greater risk of potential side effects, especially for older people. Studies of older adults show that those with long-term chronic NSAID use increase their risk of:

  • peptic ulcers
  • renal failure
  • stroke and heart disease

Chronic NSAID use also worsens many diseases, including heart disease and high blood pressure.

NSAID drugs purchased OTC and prescription NSAIDs have recommended dose levels and durations printed on the label. But a 2015 European study found that 97 percent of people with chronic pain took NSAIDs for more than 21 days.

A 2016 review of many NSAID studies found that stomach ulcers, bleeding, or perforation occurred in about 1 percent of people taking NSAIDs for three to six months. The percentages increased to between 2 and 4 percent for people taking NSAIDs for a year.

The same study noted that long-term NSAID use resulted in kidney damage and eye damage. As a precaution, this study advised that people using NSAIDs long term should have periodic blood tests to monitor changes.

If you have to take NSAIDs every day for chronic pain, there may be other drugs you can take to lessen the side effects of NSAIDs. Discuss this with your doctor.

Reactions to NSAIDs vary by individual. The way NSAIDs work also varies. You may have to try different types of NSAIDs to find one that works well for you.

Children and teens who have viral infections shouldn’t take aspirin or drugs containing aspirin, because there’s a risk of the potentially fatal Reye’s syndrome.

If you have a health condition that affects your heart, liver, or kidneys. discuss alternatives to NSAIDs with a doctor.

If you’re pregnant, discuss the possible effects of NSAIDs on the fetus after 30 weeks.

Be aware that alcohol may exacerbate the side effects of NSAIDs, especially stomach bleeding.

NSAIDs are one of the common causes of adverse drug interactions.

NSAIDs shouldn’t be mixed with other NSAIDs. The exception to this is combining a low-dose aspirin with another NSAID for heart attack and stroke prevention. Discuss this with your doctor.

NSAIDs aregrouped by their chemical characteristics, selectivity, and half-life. The NSAIDs in use today are formulated from either:

  • acetic acid
  • anthranilic acid
  • enolic acid
  • propionic acid

Here are some commonly used NSAIDs:

OTC NSAIDs

  • aspirin compounds, including:
    • Anacin
    • Ascriptin
    • Bayer
    • Bufferin
    • Excedrin
  • ibuprofen, including:
    • Motrin
    • Advil
    • Midol
  • naproxen sodium, including:
    • Aleve
    • Naprosyn

Prescription

  • celecoxib (Celebrex)
  • diclofenac (Voltaren)
  • diflunisal
  • etodolac
  • fenoprofen (Nalfon)
  • flurbiprofen
  • ibuprofen
  • indomethacin (Indocin)
  • ketoprofen
  • ketorolac tromethamine
  • meclofenamate sodium
  • mefenamic acid (Ponstel)
  • meloxicam (Mobic)
  • nabumetone
  • naproxen sodium (Anaprox, Naprosyn)
  • oxaprozin (Daypro)
  • piroxicam (Feldene)
  • sulindac
  • tolmetin
  • salicylate
  • salsalate (Disalcid)

Some NSAIDs work quickly, within a few hours. Others take longer, sometimes one or two weeks, to build up to an effective blood level of the drug.

Some NSAIDs are available in slow-release form or as a patch or gel. Other drug-delivery systems are being researched.

It’s important to take the full dose every day. Otherwise, you won’t know if the particular drug is helping you.

It’s equally important that you don’t take more than the dose your doctor prescribes. Doing so may increase your risk for side effects without any added benefit.

NSAIDs can bring relief, especially if you have chronic pain. But like all drugs, the benefits come with some risks. With NSAIDs, stomach problems are the most common side effect.

If your side effects are mild, you may be able to take another drug to lessen the effects. If NSAIDs aren’t appropriate for you, there are likely to be other treatment options.

People with heart, kidney, or digestive conditions, and older people in general, are more likely to have a risk for side effects.

In general, discuss any diseases and all your medications and supplements with your doctor to rule out any possible adverse reactions with NSAIDs.

NSAIDs are very commonly used and well researched, so it’s likely that there’ll be new drug and treatment options in the future.