Opioid-Free Anesthesia: Yes, it is possible. Opioids are effective in multiple pathways for treatment of pain (transmission, modulation, and perception). Adverse effects of opioids include nausea, vomiting, constipation, respiratory depression, hyperalgesia, etc. Opioid-free anesthesia (OFA) may be a realistic method of delivering safe and effective anesthetics. Like all anesthetics, planning and preparing type of anesthetic should be individualized to patient and procedure