Tramadol is an opioid agonist that may be used to treat moderate to moderately severe chronic pain in adults, when other pain treatments such as non-opioid pain medicines do not treat your pain well enough, or you cannot tolerate them. Tramadol ER is used to treat chronic pain that can't be managed with other pain relievers. Learn about its side effects, cost, dosage, and interactions. Learn about the side effects of tramadol, from common to rare, for consumers and healthcare professionals. What is tramadol, and what is it used for? Tramadol is a synthetic (man-made) pain reliever (analgesic). Researchers and doctors do not know the exact mechanism of action of tramadol, but it is similar to morphine. To control medium to severe pain, there is no better option than taking tramadol. Being an opioid agonist, it works on the opioid receptors in the brain & body. When other painkillers do not relieve, tramadol dosage works well. To control pain, it works on the central nervous system. Learn about tramadol usage and dosing. Read the latest news and reviews about the drug as well as potential side effects and popular alternatives. Tramadol: learn about side effects, dosage, special precautions, and more on MedlinePlus Find patient medical information for Tramadol (Ultram, Conzip, Qdolo) on WebMD including its uses, side effects and safety, interactions, pictures, warnings, and user ratings Effects of tramadol and O-demethyl-tramadol on human 5-HT reuptake carriers and human 5-HT3A receptors: a possible mechanism for tramadol-induced early emesis. Tramadol belongs to the group of medicines called opioid analgesics. It acts in the central nervous system (CNS) to relieve pain. When tramadol is used for a long time, it may become habit-forming, causing mental or physical dependence.