A man in his 40s is in a serious condition in hospital after taking drugs stolen from a veterinary practice, police believe.
Thieves burgled the Basingstoke vet clinic on Monday night, taking various prescription medications for animals, which police warn may now be circulating in the community.
These included Isoflurane, an anaesthetic drug under the brand name Iso-Flo, which can cause a life-threatening reaction if inhaled, swallowed or injected.
Hampshire Police issued an urgent warning on Tuesday night, after a man was taken to hospital earlier that evening from a property in Basingstoke town centre.
"Anyone who has taken animal medicines or who knows someone who may have taken them, should seek medical help immediately," the force said.
A 36-year-old man has been arrested and remains in custody, police said.
"If you are offered anything suspicious please inform the police IMMEDIATELY," GP Vets wrote on Facebook on Tuesday morning.
"We cannot stress how dangerous some of these medications can be to both humans and animals."
Anyone who is offered the drugs or has information of their whereabouts is asked to call 101 and quote 44200238349.
The public are advised not to touch any suspicious discarded drug packaging, bottles or canisters, but to instead call 101 and allow officers to pick them up safely.
Additional reporting by PA