Final answer:
Methadone is the opioid most commonly used to treat shivering upon emergence.
Step-by-step explanation:
The opioid most commonly used to treat shivering upon emergence is methadone. Methadone is a synthetic opioid that is less euphorigenic than heroin and similar drugs. It is often given to individuals experiencing opioid withdrawal to make the process less difficult. Methadone clinics help people manage withdrawal symptoms through the use of methadone.