Several cylinders containing so-called laughing gas have been stolen from an ambulance station in Suffolk.
The East of England Ambulance Service is urging the public to keep an eye out for the cylinders of entonox taken from Stowmarket on Monday morning.
It said staff arrived at work to find they were missing from the store.
Medical director Pam Crispin said the cylinders hold a pain-killing anaesthetic gas, which has a variety of side-effects if used incorrectly.
These include feeling sick and a condition called tension pneumothorax, which can be very serious, she added.