Opioid medications are a powerful class of prescription drugs that can help control severe pain. These drugs can be injected or taken in pill form. Once in the body, opioids mimic naturally occurring chemicals in the body to help block pain signals. Some examples are oxycodone, hydrocodone, and codeine. So are morphine and fentanyl. Opioids can be helpful for some types of pain, but they require responsible use as they can become addictive-forming with long-term use.