Legislation signed by Gov. Mike Pence in March allows trained police, firefighters and other first responders to deliver Naloxone or similar drugs to treat overdoses.
Police will now be able to carry the medications to use if they find someone overdosing.
The new policy comes amid rising reports of heroin abuse in Indiana.
Heroin use reported by addicts getting treatment rose from 2.6 percent in 2001 to 6.6 percent in 2010, the most recent year for which statistics were available.