The incident took place at Monklands Hospital in North Lanarkshire on Wednesday between 22:25 and 23:20.
Police have warned the public of the "potentially serious or fatal" consequences of taking the drugs if they are offered them.
The stolen items included vials of adrenaline, glyceryl trinitrate sprays and hydrocortisone sodium phosphate.
Police have urged anyone who comes across any discarded drugs to hand them in to their local police station.
Anyone with information about the theft is also asked to contact officers.
Prescription drugs were stolen from an ambulance while it was parked outside a hospital's accident and emergency unit.