How do analgesics work on pain? Answered by Craig C. Freudenrich and Discovery Fit & Health Contributor Craig C. Freudenrich When you're injured or have a headache, you reach for the bottle of pain relievers. All that matters at that point is that the pills or capsules work -- and quickly. To understand how analgesics relieve pain, it helps to first understand how your brain perceives pain. Pain perception, or nociception, is the process by which a painful stimulus is relayedfrom the site where you're injured to the central nervous system (brain, spinal cord). There are several steps in this process: 1.Injury-- Mechanical injuries, such as pressure, punctures and cuts or chemical (burn) stimuli injure tissues. The injured tissues release chemicals (potassium, prostaglandins, histamines, bradykinin and substance P). 2.Reception-- A specialized nerve cell called anociceptor senses the stimulus and the chemicals released from injured tissues.