You are PROTECTED from criminal and civil prosecution when giving naloxone in good faith. Don’t delay or be afraid to call for help.
There are laws that help protect you when giving someone naloxone and calling for help in an overdose situation. What’s important is that if you act in good faith and with reasonable care in responding to an overdose, the law will protect you.
The Good Samaritan Law says the overdosing drug user, or someone who is using with them, cannot be arrested (from possession charges and illicit use of controlled substances) when seeking treatment for him/herself or calling for medical assistance for someone else (you can read the actual law in Section 333.7403 below).
However, this law does not protect someone if they have a felony warrant for their arrest, or if they are on parole, and if the number of drugs they possessed was more than for personal use. Despite this, in many places, the police officers are not there to arrest people, but to save live and help people seek recovery. They know an overdose is a medical emergency, not a criminal investigation.
For a list of overdose prevention laws in the different States, check out the Prescription Drug Abuse Policy System (PDAPS) resource.