The fee for a prescription from the pharmacy goes up on 1 January from $3 to $5. But prescriptions remain free for children under the age of six.
Labour says people are already struggling and this will come as a nasty shock to those who need prescriptions over the summer holidays.
Health Minister Tony Ryall said efforts have been made to publicise the changes through the media and pharmacies.
And he said if people can't afford their prescription, they should talk to their doctor about how to get the fee waived, or go to Work & Income.
Mr Ryall also said the increase is only for the first 20 items. Any more afterwards this year are free.