Three vials of painkiller gas have been stolen from paramedics treating a suspected snakebite victim at Albany Creek, in Brisbane's north.
Paramedics were attending to a man thought to have been bitten by a snake in Cuthbert Park about 10.45pm when the vials of Penthrane, a mild analgesic, were stolen.
As it was, the snakebite report turned out to be a false alarm.
A bag, which originally contained the vials, was returned to police about 2am on Saturday, but the Penthrane was missing.
Police said Penthrane, if taken in a large enough dose, could be fatal.
It is banned in the United States and there are concerns for Australian paramedics administering the drug because of its potential for a build up of gasses which can cause severe vomiting.
Police said a 16-year-old youth was assisting them with their inquiries.