Folds labeled "Instagram" were found in all four cases, authorities say.
An especially dangerous batch of heroin may be making its way around Phillipsburg, police warn.
Four people overdosed on heroin between Friday and Saturday, town police said in a news release. All were saved when police used an antidote, according to Lt. Michael Swick.
In all four cases, a blue "Instagram" stamp was found on wax folds of suspected heroin, authoritites said.
"This (announcement) is intended for the safety and welfare of individuals suffering from addiction," the news release said.
Police in New Jersey and the Lehigh Valley are increasingly being trained to administer opiate overdose antidotes like naxalone, sold under the brand name Narcan. Experts say that surviving a near-death experience could be a wake-up call for addicts.
Is overdose antidote worth it?
"Most overdoses occur in people who have a pretty high tolerance, as in you've built up your usage so you're using much higher quantities than one would use if you never used before," William Matthews, from the New York City office of the Harm Reduction Coalition, told lehighvalleylive.com earlier this month.
"The person who overdoses wakes up and as they are waking up they are waking up in withdrawal," he said. "It varies from being really uncomfortable to being really horrible. This is a safety net that no one wants to fall into."
The medicine was used about 50 times last year in Warren County, and about 15 times as of mid-May, Prosecutor Richard Burke previously said.
Steve Novak may be reached at snovak@lehighvalleylive.com. Follow him on Twitter @type2supernovak. Find lehighvalleylive.com on Facebook.