In the first robbery, Nikolai Burroughs drove his mother's BMW to Pharmacy 257 and after masking his face with a hoodie and bandanna, he used a small knife to rob the female pharmacist of the lethal painkiller oxycontin.
Oxycontin is a highly addictive painkiller containing morphine and is dubbed "hillbilly heroin" or "OC" in America and linked to hundreds of US deaths involving non-medical use.
Medical experts say the drug is more potent and addictive than heroin.
The second robbery occurred about 2.20pm on October 10, 2011, after mother and son, who are both addicted to oxycontin, devised a plan to rob another pharmacy.
After Burroughs-Mather drove her son to Maungatapu Pharmacy, he entered the pharmacy armed with a knife and wearing a mask like the one that featured in the movie Scream and demanded drugs from staff inside the store.
Once he was given some of the drugs he fled.
When police searched his mother's Ranch Rd home the next day they found some of the stolen drugs and pieces of the mask.
The pair were sentenced on Tuesday.
Burroughs-Mather was sentenced to 12 months home detention, which the Bay of Plenty Times understands will be served at a Housing New Zealand rental property recently allocated to her.
But Judge Thomas Ingram warned her that any breach of her sentence conditions, particularly the ban on possessing or consuming alcohol and non-prescription drugs, would mean jail.
Lawyers for both mother and son urged the judge to show some leniency given the background to the robberies and their client's addictions.
Judge Ingram refused a Bay of Plenty Times request to take an in-court photograph of mother and son mainly because of their addictions.