The government is pushing out positive news about health services but it isn't stemming a tide of criticism over increased prescription charges.

Health Minister Tony Ryall says disability services will get an extra $143.7 million in next week's budget, and that's on top of the $101 million he announced on Monday for cancer treatment.

But Labour is focused on the downside of health spending - prescription charges going up from $3 to $5 in January next year to save $40 million a year.

Labour leader David Shearer says the "sudden decision" to force people to pay more for health services is proof the government has mismanaged the economy.

"Increased charges for health care puts the burden on those who can least afford it," he said on Tuesday.

"The result is likely to be more people choosing not to pick up their medication and more spending down the track on treatment when they become seriously ill."

And Labour's disability spokeswoman, Clare Curran, wants to know where the $143.7 million is going to come from.

"If the government is making cuts in other areas it should be transparent rather than simply dressing it up as `new money'," she said.

Mana Party leader Hone Harawira, who represents the poorest electorate in the country, is warning children could die if parents can't afford medicines.

"I can't believe the government could be so callous," he said.

Mr Ryall says opposition parties never agree with anything the government does.

"This is a modest increase and if people can't afford things they can go to Work and Income, there's a support infrastructure in place," he said.

The price hike, the first in 20 years, will affect the first 20 prescriptions per person or family a year, after that medicine will continue to be free.