Acting chief pharmacist Bruce Battye said there were concerns about the increased use of the painkiller, dubbed ''hillbilly heroin'', over the past few years.

Oxycodone is a morphine-based medication prescribed to people suffering from cancer or other debilitating conditions.

Mr Battye said some patients were manipulating and pressuring doctors into prescribing the drug, which could cost as little as $5 for 20 tablets under the Pharmaceutical Benefits Scheme.

Each tablet then had a street value of up to $50.

''Unfortunately, some doctors who are targeted by these patients, before they know it they have a lot of these patients on their hands,'' Mr Battye said.

''When they have those 20 tablets in their hands they suddenly have 20 times $40 or $50.''

Mr Battye said addicts commonly crushed up and injected some of the tablets and sold the rest.

He said the ability to profiteer on oxycodone was so great there were instances where people were willing to pay $700 for 240 tablets without the PBS subsidy to sell the drugs on.

But in the hands of the wrong person oxycodone could cause nausea, drowsiness and even death, he said.

Any concerns at NSW Health about the quantity of oxycodone being prescribed are first dealt with through a one-on-one educational session with doctors, who are warned about the consequences. If the high level of prescriptions continues, the doctor is investigated.

Mr Battye said up to 20 doctors had been investigated for wrongly prescribing the painkiller this year.

''We probably referred maybe a dozen doctors, maybe up to 20 doctors, to the Health Care Complaints Commission or the Medical Board for inappropriate prescribing,'' he said.

Six doctors in one unnamed regional area of NSW were counselled, after which four of them altered their prescribing practices. AAP