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. 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. 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. Tramadol: learn about side effects, dosage, special precautions, and more on MedlinePlus Overview: Tramadol is an opioid pain medicine used to treat severe pain. It works by changing how your brain feels and reacts to pain. People take it by mouth as a tablet, capsule, or liquid. 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 is approved for the treatment of pain in adults that is severe enough to require an opioid analgesic and for which other treatments do not work or are not tolerated. Opioids should be used only when alternatives are inadequate. Tramadol can put you at risk for overdose and death. Tramadol is an opioid medication that may be used to treat moderate to moderately severe chronic pain in adults, including pain after surgery. 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.