Derived mostly from poppy seeds, opioids are drugs with powerful effects. They fall into two broad categories: illegal street drugs such as heroin, and prescription pain medication such as morphine and Percocet.
Opioid addiction happens when one becomes physically or psychologically dependent on the drug. Individuals can become dependent even through supervised legal use of their medication. For example, patients with chronic illnesses sometimes experience withdrawal when they stop using the drugs, even though they do not have a psychological dependence.
Opioid addiction can be extremely dangerous: non-medical users take higher than recommended doses, and they have a tendency to use the drugs in conjunction with other substances, like alcohol or other drugs. It is easy to accidentally overdose on opioids, and overdoses can be fatal.
Street drugs like heroin are very harmful as well: they are often mixed with other substances that can poison the human body. Fatal overdoses can happen even when the drug is taken in small amounts.