In the US, moderate-to-severe pain is treated with the prescription drug tramadol. It functions as a synthetic opioid by changing the way the brain interprets pain. Although many people find Tramadol to be useful, there is a risk of addiction and overdose, which is why the FDA has classified it as a Schedule IV prohibited medication. Due to possible adverse effects such nausea, dizziness, and respiratory depression, patients should only use it under close medical supervision.