A Hepatitis C positive drug addict who robbed a northside chemist with a blood-filled syringe will spend one-year behind bars.

Aaron Khan pleaded guilty in the ACT Supreme Court and was on Monday convicted of aggravated robbery at Capital Chemist in O'Connor.

Khan admitted at a sentencing hearing last week that he used a syringe as a weapon because he knew it would scare the pharmacy employee into handing over drugs.

On September 2, the 28-year-old entered the Sargood Street store about 10.30pm and threatened staff with a blood-filled syringe, demanding morphine sulfate.

Staff members handed over five-packets of the narcotic and he left the shop.

The court heard he knew he was infected with blood-borne disease Hepatitis C at the time.

Khan said he carried out the robbery because he was being stood over for $190.

The defence tendered records of text messages sent to the defendant in the days leading up to the robbery.

One text said: "Don't make me call the boys."

Khan said he thought he would be kidnapped and harmed if he did not obey.

"I was reluctant to do it ... [but] I was scared," he said.

"I wasn't thinking about the consequences."

The court heard Khan demanded prescription drugs because it had "high appeal on the street".

But he denied the prescription medication was for personal use.

"I'm an amphetamine addict, not a morphine addict.

"If it were for me I would've taken amphetamine or methamphetamine."

Chief Justice Terence Higgins said Khan's early guilty plea and minor criminal history entitled him to leniency.

"[But] the offence is a serious one and one which attracts a period of imprisonment," Chief Justice Higgins said.

"The question is how much of that sentence should be served."

Chief Justice Higgins noted Khan had an "unfortunate background", including being a victim of domestic violence as a child, drug and alcohol abuse and mental illness.

The judge accepted the defendant felt genuine remorse and showed good prospects of rehabilitation.

He jailed Khan for three-years, backdated to take into account 96-days already spent in custody, with a non-parole period of 12-months.

Chief Justice Higgins said Khan should spend his time behind bars in the Solaris Program – a therapeutic course for the treatment of substance misuse.