Opioid
Opioids are substances that, when reaching opioid receptors, have effects similar to those of morphine. Medically they are primarily used for pain relief, including anesthesia. Other medical uses include suppression of diarrhea, replacement therapy for opioid use disorder, reversing opioid overdose, suppressing cough. Extremely potent opioids such as carfentanil are approved only for veterinary use.