The young man, wearing dark clothes and armed with the syringe, entered the Emily Roberts Amcal Pharmacy in Lowndes Street about 11am.

He walked up to the counter and demanded a specific type of medication, police said. A woman shop attendant handed it over and the man fled.

Three other staff were inside the pharmacy during the robbery.

The incident lasted no more than 40 seconds, police said.

Staff were shaken but not hurt.

Detective Sergeant Brendon Murphy from the crime investigation unit said the man did not say what the syringe contained.

He agreed it was possible that if he was desperate, the thief could target other local drug suppliers.

Detective Sergeant Murphy advised staff in pharmacies always to comply with demands if threatened.

”Just do what these people have done,” Detective Sergeant Murphy said.

Police say the man they are looking for is a Caucasian, aged in his mid-20s to early 30s.

He is about 173cm tall and is of thin to medium build.

The man was believed to be wearing a dark jacket and jeans during the robbery.

Officers door-knocked homes in the area yesterday, and are urging anyone with information about the man to contact police.

The Bendigo crime investigation unit can be contacted on 5448 1300.

Crime Stoppers can be reached on 1800 333 000, and callers can remain anonymous.