Opioids are a class of drugs known colloquially as "painkillers" and include a vast array of similar chemical compounds. The CDC defines opioids as natural, synthetic, or semi-synthetic chemicals that interact with opioid receptors on nerve cells in the body and brain and reduce the intensity of pain signals and feelings of pain. This class of drugs includes heroin, synthetic opioids such as Fentanyl, and pain medications available legally by prescription, such as oxycodone, hydrocodone, codeine, morphine, and many others.
There can be some confusion when the term "opiate" is also used since it is not always interchangeable with "opioid." Opiates are only those opioids that are natural, such as Morphine or codeine.
This has also been loosely extended to heroin and other opioids that are not entirely synthetic and derived from natural opiates. But the term "opioids" is more inclusive and refers to ALL drugs of the above definition, including natural opiates.
Opioids work by activating opioid receptors on nerve cells that exist throughout the body. These receptors serve to diminish the signals of pain by blocking them. They also are responsible for some sensations of pleasure and enjoyment. While the term "opioid receptor" is a bit of a misnomer, it is commonly accepted and used to describe this system. As with much of science, opioid receptors were discovered after opioids, and so their naming occurred in reverse order. This is similar to the discovery of the endorphin, or the native particle which opioids mimic. Yet despite this relationship, the word endorphin is a coined term that derives from the morphing of the words "endogenous" and "morphine," quite literally meaning "the morphine within."
The History of Opioids
As is the case with virtually every drug, the story of opioids begins with a natural life form, plants. In this case, the poppy is the plant, a rather delicate and beautiful flower that grows wild around the world.