NSAIDs: Uses, Mechanism of Action, Side Effects, Interactions and Warnings

Nonsteroidal anti-inflammatory drugs are drugs that help reduce inflammation.

NSAIDs tend to work quickly and generally have fewer side effects than corticosteroids, which also help with inflammation.

However, before using an NSAID, you should know the possible side effects and interactions with other drugs. Read on for this information, plus tips to help you use them safely and effectively.

Mechanism of action

Prostaglandins are a family of chemicals produced by cells in the body and have several essential functions.

They promote inflammation necessary for healing and cause pain and fever; support the blood clotting function of platelets, and protect the stomach lining from the damaging effects of acid.

Prostaglandins are produced within the body’s cells by the enzyme cyclooxygenase (COX). There are two COX enzymes, COX-1 and COX-2. Both enzymes produce prostaglandins that promote inflammation, pain, and fever.

However, only COX-1 produces prostaglandins that support platelets and protect the stomach. NSAIDs block COX enzymes and reduce prostaglandins throughout the body. As a consequence, inflammation, pain, and ongoing fever are reduced.


NSAIDs can help reduce many types of discomfort, including:

  • Headache.
  • Back pain.
  • Muscle pains.
  • Swelling and stiffness are caused by arthritis and other inflammatory conditions.
  • Period pains.
  • Pain after minor surgery.
  • Sprains or other injuries

Side effects

Just because you can buy NSAIDs without a prescription does not mean they are perfectly safe. There are some possible side effects and risks.

Since the prostaglandins that protect the stomach and support platelets and blood clotting are also reduced, NSAIDs can cause stomach ulcers and promote bleeding.

Some of the more common side effects include:

  • Diarrhea.
  • Stomach ache.
  • Gases.

These side effects can be lessened by taking your medicine with food, milk, or antacids. NSAIDs can cause lightheadedness, dizziness, or a mild headache; however, it is rare.

Serious side effects that require immediate medical attention include:

  • Blurry vision.
  • Rash, hives, and itching.
  • Fluid retention.
  • Blood in your urine or stool.
  • Vomiting
  • Severe stomach pain
  • Chest pain.
  • Fast heartbeat
  • Jaundice.

NSAIDs are intended for occasional and short-term use. The risk of side effects is proportional to the amount of medicine you take and the time you take them.


NSAIDs can interact with other medications. Sometimes this interaction can make your drugs less effective. Two examples are blood pressure medications and low-dose aspirin when used as a blood thinner.

Other combinations can also cause serious side effects. These include the use of an NSAID with:

Warfarin: NSAIDs can enhance the impact of warfarin (Coumadin), a drug used to prevent or treat blood clots. That combination can lead to excessive bleeding.

Cyclosporin the cyclosporin is used to treat arthritis or ulcerative colitis. It is also prescribed for people who have had an organ transplant. Taking it with an NSAID can cause kidney damage.

Lithium – Combining NSAIDs with the mood-stabilizing drug lithium can lead to a dangerous build-up of lithium in your body.

Aspirin:  Taking NSAIDs with low doses of aspirin can increase the risk of developing stomach ulcers.

SSRIs: Bleeding within the digestive system can also be a problem if you take NSAIDs with selective serotonin reuptake inhibitors.

Diuretics: It is generally not a problem to take NSAIDs if you also take diuretics. However, your doctor must monitor your high blood pressure and kidney damage.


Elderly patients are at increased risk for these adverse events. NSAIDs (except low-dose aspirin) can increase the risk of life-threatening heart attacks, strokes, and related conditions.

This risk may increase with the duration of use and in patients with underlying risk factors for heart and blood vessel disease. Therefore, NSAIDs should not be used to treat pain resulting from coronary artery bypass graft surgery.

 Nonsteroidal anti-inflammatory drugs in children

Children under 18 years of age who may have chickenpox or the flu should avoid aspirin and aspirin products (a type of NSAIDs).

Giving aspirin to children can increase the risk of Reye’s syndrome, which can lead to liver and brain damage. Reye’s syndrome is potentially fatal.

Tips for using NSAIDs without a prescription

Assess your needs

Some over-the-counter medications, such as acetaminophen (Tylenol), are suitable for relieving pain, but they don’t help with inflammation. NSAIDs are probably the best option for arthritis and other inflammatory conditions if you can tolerate them.

Read the labels

Some over-the-counter products combine acetaminophen and anti-inflammatory drugs.

Nonsteroidal anti-inflammatory drugs can be found in some cold and flu medications. Be sure to read the ingredient list for all over-the-counter medicines to determine how much of each medication you are taking.

Taking too much of an active ingredient in combination products increases your risk of side effects.

Store properly

Over-the-counter medications can lose effectiveness before the expiration date if stored in a warm and humid place, such as your bathroom medicine cabinet. To make them last, keep them in a cool, dry place.

Take the correct dose.

When taking an over-the-counter nonsteroidal anti-inflammatory drug, read and follow the directions. Products vary in intensity, so make sure you take the correct amount each time.

Ask your doctor

NSAIDs are not a good idea for everyone. Before taking these medications, check with your doctor if you have:

  • An allergic reaction to aspirin or another pain reliever.
  • A disease of the blood.
  • Stomach bleeding, stomach ulcers (peptic ulcers), or intestinal problems.
  • High blood pressure or heart disease.
  • Liver or kidney disease

You should also talk to your doctor about the safety of using an NSAID if you consume three or more alcoholic drinks per day or if you take blood-thinning medications.