If you are in pain and want to buy Tapentadol 100mg online, you should first find out how and why it works as a pain reliever. Tapentadol is an opioid painkiller that is sold under the brand name Nucynta. It is used to treat moderate to severe pain. It is a new opioid that works in the brain and has a dual mechanism of action that includes both activation of mu-opioid receptors and blocking of noradrenaline reuptake. It’s only for adults because it’s a strong painkiller.