Both illicit fentanyl and carfentanil are really dangerous opioids which could bring about A fast overdose and Dying when abused, but carfentanil is much more potent than fentanyl. Multiple doses of the anti-overdose drug naloxone (Narcan) will not be effective to reverse an overdose. Proceed reading throughFentanyl OD or W/D!!! Not sure, need to h