Final answer:
A substance with pain relieving properties is called an analgesic, with opioids being powerful prescriptions and OTC options like acetaminophen and NSAIDs used for milder pain.
Step-by-step explanation:
A substance or mechanism that has pain relieving properties is called an analgesic. Analgesics such as aspirin and acetaminophen work by reducing the sensation of pain. Some analgesics, like opioids, include drugs such as morphine, methadone, hydrocodone, and oxycodone, which are very powerful and can lead to abuse and addiction. These substances act by mimicking the body's own pain relief mechanisms by binding to opioid receptors in the brain. On the other hand, there are also over-the-counter (OTC) options like acetaminophen and NSAIDs, which include aspirin, ibuprofen, and naproxen. It's essential to understand the differences amongst these pain relievers, as opioids have a high potential for misuse and should be used under careful supervision, whereas OTC pain relievers are more suitable for minor aches and pains.