Does Xylazine have a taste? What is xylazine? Xylazine is a veterinary sedative (used on large animals). It is not an opioid. In humans it causes: 1. Extreme sedation. 2. Slowed breathing and heart rate. 3. Dangerous drops in blood pressure. 4. Severe skin ulcers / tissue death (even away from injection sites). Narcan does not reverse xylazine, because it isn’t an opioid. So when fentanyl is mixed with xylazine, you can revive the opioid part… but the person can still stop breathing from the xyl