Non-steroidal anti-inflammatory drugs (NSAIDs) and acetaminophen are both types of pain relievers that can be sold over the counter. The most significant difference between NSAIDs and acetaminophen is that NSAIDS reduce inflammation, but acetaminophen does not. This difference is due to the way that each drug acts on chemicals called prostalgadins.
NSAIDs and acetaminophen both belong to a wider class of drugs called non-opioid analgesics. These drugs block the production of prostaglandins. Prostaglandins perform a number of functions, including increasing pain, fever and inflammation. Acetaminophen inhibits the production of postalgadins only in the central nervous system, which is made up of the brain and spinal cord. NSAIDS, on the other hand, decrease production of postalgadins in both the central nervous system and the peripheral nervous system, or nerves outside the brain and spinal cord.
Since NSAIDs reduce prostaglandin production at the site of the injury itself, they also reduce swelling, unlike acetaminophen. This makes NSAIDs the preferred treatment for most joint pain, muscle pain and arthritis, which are usually accompanied by inflammation. Acetaminophen is as effective as NSAIDs for headaches and fever reduction in most patients.
Which type of pain reliever is best, however, largely depends on the patient. Even within the NSAID class, each type of drug works in a slightly different manner, and some people may respond better to one than the other. Trial and error is generally the only way to determine what type of pain reliever a patient should use.
Both NSAIDs and acetaminophen carry some risk of side effects and complication from overdose. NSAIDs may cause problems in the stomach or intestines by reducing protective prostaglandins in the digestive tract, and may also increase blood pressure or damage the kidneys if used over a long period of time. Acetaminophen, on the other hand, has little to no effect on the digestive system, but it may decrease liver function. NSAIDs and acetaminophen are more likely to cause damage in people who consume three or more alcoholic beverages per day. A suspected overdose of either type of pain reliever requires immediate medical attention.
Common over-the-counter NSAIDs include aspirin, ibuprofen, also known as Advil®, and naproxin, also known as Aleve®. A few NSAIDs are only available by prescription, such as Celebrex® and Daypro. Acetaminophen is sold under the brand names Tylenol® in the United States and Paracetamol® in most other countries.