Pharmacists across Australia are bracing for angry customers later this week when they’re told they can’t buy medicines with codeine over the counter.

From Thursday, products including Nurofen Plus, Panadeine and Mersyndol will be banned for sale without prescription.

Pharmacy Guild of Australia spokesperson Greg Turnbull told Nine.com.au there was some trepidation among pharmacists about how customers would react to the news, despite the change in classification of the medicines being well publicised.

“Pharmacists are the most accessible health professionals we have. So lots of people go to a pharmacy for their needs as their first port of call and many people are used to being able to buy these medicines over the counter,” Mr Turnbull said.

“They may well express not only disappointment but anger if they are denied access to this medicine.”

There have also been reports of customers stockpiling the medication in the lead up to the ban.

Mr Turnbull said pharmacists had a responsibility to limit how many packets of codeine a customer could buy.

However, he had heard anecdotally of an increase in small amounts of packets of codeine-based medicines being purchased.

The Therapeutic Goods Administration said the decision to require prescriptions is based purely on safety, with accidental drug overdoses now more likely to be caused by pharmaceutical drugs than illegal drugs.

All codeine-based painkillers will require a prescription from Thursday. (9NEWS)

It is believed codeine is responsible for about 100 deaths a year - approximately two deaths every week.

Australian Medical Association vice president, Dr Tony Bartone, has commended the TGA’s decision to reclassify codeine.

“These medications are serious medications,” Dr Bartone told 9NEWS.

“Opioid dependency is a worldwide problem. It is an area that needs urgent attention.”

The changes are expected to affect millions of Australians living with chronic pain.

Anyone who routinely uses codeine is encouraged to seek medical advice from their doctor before the changes kick in.

Mr Turnbull said the Pharmacy Guild of Australia was now calling on the introduction of real-time recording for doctors’ prescriptions to prevent patients who are addicted to codeine from “doctor shopping”.

“At the moment there is nothing to help a doctor understand if a patient has had a script for a medication the day before from another doctor,” he said.