Durham Police are warning young people against a "dangerous new trend" that involves vaping the cannabis derivatives CBD and THC.
It comes after a boy from Barnard Castle was left "debilitated" after taking the "harmful concoction" which can cause "nasty" side-effects, Durham Police said.
The dull yellow liquid had been sold in sports drink bottles and distributed in small, unlabelled bottles - a large quantity has been seized by police.
A force spokesperson said: "Thankfully the teenager was at home at the time and was able to get help when he became unwell.
"But officers particularly want to warn any young people who may be offered or use the liquid, especially in remote areas around Barnard Castle and Teesdale."
THC is the main psychoactive compound in cannabis that produces the high sensation, while CBD is a now legal compound of the drug which is available to buy in many shops.