Two groups of healthcare workers announced strike action today in separate protests against the HSE.
Section 39 workers are set to strike next month after pay talks at the Workplace Relations Commision collapsed.
The voluntary groups provide social services and healthcare on behalf of the HSE.
SIPTU says an agreement that pays restoration would begin by the end of 2018 has not happened, and staff will be striking on September 18.
"After months of intense campaigning, our @siptuhealth members in Section 39 organisations feel that what is being offered is too little, too late and will be striking on Tuesday 18th September." #S39 @irishcongress https://t.co/zTSEzwTBki— SIPTU (@SIPTU) July 25, 2018
SIPTU Health Division Organiser, Paul Bell, said: “Our members deferred strike action in February in good faith following an agreement between the parties that pay restoration would begin by the end of 2018. This has not happened and our members' patience has worn thin.”
"After months of intense campaigning our members feel that what is being offered is too little, too late and will be striking on Tuesday 18th September.
"Our members will do everything possible to protect service users throughout the periods of strike," he said.
Labour Health spokesperson Alan Kelly TD repeated his call for the pay of Section 39 workers to be restored and said the Government had failed them by not reaching agreement on starting pay restoration by the end of 2018.
"I cannot understand why the Government, which has said it wants to resolve this issue, has allowed it to reach this point," Mr Kelly said.
"In the context of the overall health budget of nearly €15 billion I find this failure to reach agreement over €1.5 million bizarre.
"The people who rely on these services cannot be let down by the Government who seem intent on washing their hands of the problem," he said.
Meanwhile, The Psychiatric Nurses Association is to ballot their ambulance personnel members for industrial action.
The PNA is protesting at the HSE's refusal to negotiate with them when representing the National Ambulance Service Representative Association (NASRA).
They're calling for the HSE to recognise that the PNA also represents ambulance staff.