Bloomington police responded to five overdoses over the weekend, continuing a spike the department first reported last week.
Police say most are the result of synthetic marijuana known as spice being laced with unknown substances.
"I've seen things that have had stuff like rat poison sprayed on leaves and then people are smoking it and then they're calling that spice," says Capt. Steve Kellams.
Kellams says the overdose antidote Naloxone can only reverse the effects of opioids, so it won't help revive those who've overdosed on spice unless it's laced with an opiate.
The department did make a spice dealing arrest over the weekend.
"At this point in time we can't verify that has anything to do with overdoses," Kellams says.
Police are still awaiting toxicology reports from a suspected overdose death the department responded to last week.