Frequently Asked Questions We have the answers you’re looking for What are the most potent opioids? + Carfentanil is approximately 10,000 times more potent than morphine and has no approved medical use in humans. Fentanyl is 50 to 100 times more potent than morphine and is the most commonly encountered ultra-potent opioid in the illicit … Continue reading List of Opioids Strongest to Weakest