Analgetics (one "analgetic") (or analgesics) is a word for some drugs that are used to stop pain. These are also known as painkillers. There are several kinds of painkillers. All act on the nervous system. Some painkillers (such as opioids) can make people addicted if they are taken for a long time. Some painkillers have side effects that can harm people when they take too much (e.g., too much paracetamol can be dangerous for the liver)