HCPCS Code J2315: Injection, Naltrexone, Depot Form, 1 mg

As with any injected medication, there will be pain and discomfort in the injection site. There could also be mild to moderate allergic reactions. Adverse reactions, though rare, include severe allergic reactions (this needs immediate attention), injection site infections (can be prevented by using antiseptics before administering the injection), and liver damage.

Oral naltrexone, buprenorphine/methadone (for opioid dependence), or behavioral therapy/counseling/support groups.

Around 15 minutes, including preparation. It may take longer if you count the monitoring period after injection.