Tapentadol 100mg is reliever used for moderate to severe pain, available in immediate-release (IR) for short-term needs (e.g., post-surgery) and extended-release (ER) for chronic pain, acting on the brain to change pain perception. It works by changing how the brain and nervous system respond to pain, with the 100mg dose often used in immediate-release for acute issues or as part of a titration schedule for ER, but it carries risks of addiction, respiratory depression, and drowsiness, requiring careful medical supervision.