The Irish Medical Organisation has described the prescription charge for medical card patients as a "regressive" policy and is calling for its abolition.
At the union's annual conference in Co Kildare, IMO President Dr Matthew Sadlier said some patients cannot afford to pay the €2.50 charge, especially if it applies to a large number of items.
Dr Sadlier said he was aware of cases where patients delay or do not get prescriptions filled as a result of the charge.
He was aware of cases where patients on ten medicines asked which five were the most important, as they only had money for those.
The charge applied to the most vulnerable and disadvantaged, he said.
The conference has debated a motion condemning the 500% increase in the charge in recent years.
The IMO said the medical evidence does not support prescription charges.
Delegates agree review of McNeice retirement package
Delegates have voted to ballot members on whether to hold an independent review into how the organisation's former chief executive was entitled to a pension of over €20 million.
George McNeice's retirement package was discussed in a private session this evening.
The issue of an independent review of Mr McNeice's retirement package was discussed at an EGM last year.
The union's members have also voted in favour of an overhaul of its constitution and rules.
The IMO said this will "ensure greater transparency and more oversight” of its financial affairs.
Dr Sadlier said: "These changes are a key part of our efforts to modernise and reform the IMO to ensure that it is fit for purpose and to ensure that members have much greater control and transparency over how it is managed."
Focus on GP care plans
Meanwhile, a row over Government plans for free GP care for children under-six is expected to dominate the conference.
GPs do not believe that proper funding is in place for free GP care and are opposed to the minister setting their fees and being able to cut them at any time.
Minister of State for Primary Care Alex White will try to encourage doctors to enter talks about talks, when he addresses the AGM tomorrow.
He has rejected claims that GPs will be swamped with extra patients.
The union has also called on Minister for Health James Reilly and the Health Service Executive to provide the public with clarity on the proposed site for the new National Children's Hospital at St James's Hospital.
The union passed a motion calling for an assurance that taxpayers' money is not being spent developing a proposal in relation to a site that will ultimately not be delivered on.
Dr John Donnellan, chairman of the Non-Consultant Hospital Doctors' Group, told the conference there was a lot of uncertainty and the planning application is delayed until 2015.
There are over 100 motions for debate at the two-day conference.