How do painkillers work? Most of us have taken painkillers from time to time, but what do they actually do? Words: Peter Stannett T here are a number of different analgesics (painkillers) available, and these are usually divided into two groups: opioids and non-opioids. The word opioid describes a substance that produces effects that resemble the physiological and/or addictive effects of opium. Non-opioid (non-narcotic) painkillers These include the most commonly used over-the-counter painkillers, such as paracetamol. This group of analgesics also has antipyretic (fever-reducing) and anti-inflammatory properties. Non-steroidal anti-inflammatory drugs (NSAIDs) such as naproxen or ibuprofen are in this group. They work by interfering with the function of an enzyme called cyclooxygenase (COX). Enzymes are proteins that control chemical reactions in the body. Two sub-types of this enzyme COX-1 and COX-2 are involved inthe control of inflammation. Theseenzymes prevent the release of prostaglandins, which enhance inflammation and cause pain. Prostaglandins are lipids (fats), which are produced at the site of injury, infection, or joints with arthritis. Hence, non-opioid anti-inflammatory drugs prevent the action of enzymes, which inhibits the release of prostaglandins which in turn dampens down the inflammation and pain. opioid or narcotic painkillers Many people cant tolerate NSAIDs because of side effects, or shouldnt have them because they may aggravate problems such as angina or raised blood pressure. So opioids, such as codeine, are often used as painkillers. They have common sideeffects such as drowsiness, nausea and constipation and, uncommonly, may lead to dependency and addiction. These painkillers bind to our natural opioid receptors (proteins that act like switches), which are involved in transmission of pain. In binding, they block pain signals to the brain from pain receptors. When activated byopioids, the brain cells also send signals to the spinal cord stopping thepain signals so there is a twopronged attack on pain, which increases the overall analgesic effect. peter stannett is information officer at arthritis Care; visit here. Opioids bind to natural receptors involved in the transmission of pain "