What are opioids?

Opioids are a class of drugs that include both natural and synthetic substances that interact with the brain's opioid receptors. This definition encompasses a wide range of medications, including opiates, which are naturally occurring substances derived from the opium poppy, such as morphine and codeine, as well as synthetic options like fentanyl and oxycodone. The key aspect of opioids is their ability to bind to opioid receptors in the brain, which can help alleviate pain but also carries a risk of addiction and other side effects.

Other choices do not capture the full scope of what opioids are. For example, while opiates are indeed drugs derived from the opium poppy, this definition is too narrow and does not include synthetic opioids. Additionally, the mention of drugs causing hallucinations does not relate to opioids specifically, as many opioids do not produce such effects. Lastly, over-the-counter pain relievers are typically non-opioid medications, such as acetaminophen and ibuprofen, and do not fit within the opioid category. Therefore, the most comprehensive and accurate definition of opioids is found in the correct choice.