Acetaminophen is the active ingredient found in non-NSAID, nonprescription pain relievers, according to WebMD. Opioids, also known as narcotics, are another non-NSAID class of pain relievers available by prescription only, explains Practical Pain Management.
Over-the-counter pain relievers fall into two classes: NSAID and non-NSAID, explains WebMD. NSAID stands for nonsteroidal anti-inflammatory drugs, and active ingredients in NSAID medications include ibuprofen, aspirin and naproxen.
Non-NSAID pain relievers such as Tylenol and some generic brands include the active ingredient acetaminophen. Acetaminophen belongs to a class of drugs called analgesics, according to MedicineNet.com. These medications relieve pain by reducing the production of prostaglandins in the brain. Prostaglandins are known to contribute to pain and swelling. Taking acetaminophen essentially increases the pain threshold, meaning that pain has to build to a higher level before patients taking acetaminophen can feel it.
Opioid pain relievers are a class of medications only available by prescription in the United States, and they are prescribed for the management of extreme pain, explains Practical Pain Management. Opioids are used only when other medications, including NSAIDs, have not been successful in alleviating pain. They carry a high risk of addiction and work by changing the brain's perception of pain. Common opioids include tramadol and oxycodone.