April 28, 2022
5 min. read

From Aspirin to Ibuprofen: Here’s How NSAIDs Work in the Body


If you’ve ever taken aspirin or ibuprofen, then you’ve taken an NSAID. Nonsteroidal anti-inflammatory drugs, or NSAIDs, are common medications that relieve or reduce pain and fever. These drugs are non-opioid analgesics that are typically used to treat less-severe pain than opioid pain relievers. 

This class of drugs includes some of the most common pain relief drugs, such as aspirin and ibuprofen, and are used by about 30 million people around the world. To find out how NSAIDs work in the body and how to use them, read our latest article below. 

What are non-steroidal anti-inflammatory drugs (NSAIDs)? 

When you have an infection or injury, the immune system responds with inflammation, which causes heat, skin discoloration, swelling, and pain in the body. Anti-inflammatory drugs like NSAIDs reduce inflammation, which treats the subsequent pain and swelling. 

You can find non-prescription over-the-counter NSAIDs in either your local drug store or supermarket. 

The most commonly used NSAIDs include: 

  • Aspirin 
  • Ibuprofen
  • Naproxen sodium 

Acetaminophen, or Tylenol, however, is not an NSAID. While it can help treat pain and fever, it does not have the anti-inflammatory properties of NSAIDs. 

What are NSAIDs used for? 

NSAIDs are commonly used to treat a number of conditions: 

They can also be used to treat fevers and aches and pains associated with the common cold. 

How do NSAIDs work? 

While the chemical structures of each NSAID is different, they have several effects in common: 

  • reducing high temperature and fever
  • decreasing inflammation
  • relieving pain

NSAIDs work by slowing the formation of prostaglandins, hormones that play an important role in the body’s inflammatory response. When an injury occurs, the body produces prostaglandins at the site of injury, where they cause inflammation. By reducing the number of prostaglandins at the site of the damaged tissue, it’s possible to lower the inflammation. 

NSAIDs also block an enzyme called cyclooxygenase (COX), which supports the reactions that produce prostaglandins. By blocking COX, NSAIDs also interfere with the body’s production of platelets—cells in the blood that play a crucial role in blood clotting—which gives these drugs additional anti-clotting properties. 

How long should I use an NSAID? 

Unless advised otherwise by your doctor, the general recommendation is not to use an over-the-counter NSAID continuously for more than three days for fever, and 10 days for pain. While these medications work well for pain relief, they are only meant for short-term use. 

If your doctor advises you to use an NSAID for a longer period of time, it’s important that you and your healthcare team are aware of the potential side effects and can change your treatment if they appear. 

How long do NSAIDs take to work? 

The time it takes for NSAIDs to work will depend on both which NSAID you are using, and the type of pain you are treating. Generally, for acute pain, NSAIDs will need to be taken every four to six hours because of their short action time. However, for conditions that require more long-term treatment, like osteoarthritis and rheumatoid arthritis, it is generally recommended to take NSAIDs once or twice a day—though taking NSAIDs this way will require waiting longer for these drugs to take effect. 

What are common side effects of NSAIDs? 

Side effects usually only occur if you are taking large doses of NSAIDs, or if you are taking them for a long period of time. Some side effects will be mild and go away with time, while others can be more serious and require medical attention. Unless otherwise specified by your doctor, it’s best not to take more than one NSAID at a time, as this can increase your risk of adverse side effects. 

The most frequently reported side effects of NSAIDs are gastrointestinal symptoms, such as:

  • Gas
  • Feeling bloated
  • Heartburn
  • Stomach pain
  • Nausea
  • Vomiting
  • Diarrhea and/or constipation

Other side effects of NSAIDs include:

  • Dizziness
  • Feeling lightheaded
  • Problems with balance
  • Difficulty concentrating
  • Mild headaches

Can I take NSAIDs if I have high blood pressure? 

If you are being treated for high blood pressure, it’s important to know that NSAIDs have been known to cause hypertension in some people. Even if you’re taking your blood pressure medications and following your diet, you may have to stop taking NSAIDs if they increase your blood pressure. 

What precautions should I consider before taking NSAIDs? 

You should limit or avoid using alcohol while taking an NSAID, as this combination of drugs can irritate the gut and increase the risk of internal stomach bleeding. 

Additionally, you should tell your doctor before combining an NSAID with any other medicine in order to avoid adverse side effects. 

You may need to avoid these drugs or take them with medical guidance if you: 

  • have an allergy to NSAIDs
  • have asthma, as NSAIDs can worsen the symptoms of this condition in some cases
  • are pregnant or breastfeeding
  • have heart disease

OTC NSAIDs are a great option for relieving short-term pain and fever. If necessary, there are also prescription NSAIDs that you can ask your doctor about to see if they are right for you. For mild conditions, such as headaches, fever from cold or flu, and period cramps, many people take NSAIDs on an as-needed basis to help manage their pain. However, if you do choose to take NSAIDs, be aware of certain precautions and keep an eye out for various side effects. If you’re not getting relief from these medications alone, talk to your doctor about your other options to find a treatment plan that’s right for you. 


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