Taoiseach Leo Varadkar has refused to interfere with a decision by Revenue to add 23% VAT to food supplements, an increase Opposition TDs claim is a "stealth tax" which will impact on those in need of vitamins.
Labour and Solidarity/PBP TDs joined people outside Leinster House protesting at plans to hike up the costs of food supplements on Friday. The increase was decided last year.
Over 60,000 people have now signed a petition to stop the VAT being put on vitamins and mineral supplements on March 1.
Labour leader Brendan Howlin called the move a "stealth tax”.
Mr Howlin said consumers, patients and ordinary people would not be able to continue with their health routines.
He said Finance Minister Paschal Donohoe should reverse the proposal.
The Labour leader also questioned how the change was being implemented without Dáil approval.
“This is very scandalous and needs to be addressed,” Mr Howlin said.
Health Stores Ireland, the association for health food stores, as well as the Irish Pharmacy Union have all come out against the VAT increase.
It is understood that Fine Gael TDs have also questioned the tax hike on supplements.
And while there are some exceptions to the new pricing regime, parties reject claims some of the products facing the extra 23% VAT charge are so-called 'snake oil' products.
Independent TD Catherine Connolly also told the Dáil the VAT move should be deferred.
“For God's sake, do the right thing and make a practical decision,” she said.
Another Independent TD Noel Grealish, who the government relies on for votes, also wants the tax hike reversed.
“This is causing concern to thousands of people,” he said, adding that one company linked with supplements here was warning of dozens of job losses if the tax move proceeds.
Responding, Mr Varadkar said he had discussed the matter with Finance Minister Paschal Donohoe, who had said that Revenue was independent.
"It is matter for Revenue, not for Government," he added.