Healthcare giant GlaxoSmithKline (GSK) is to cut its workforce by 130 as it moves some manufacturing to Spain.
The company's operations in Dungarvan, Co Waterford, are being scaled back but GSK insisted it is committed to the south-east.
The Unite trade union, which represents more than 500 of the 700 workers at two plants, said its representatives were told 48 jobs will go as manufacturing of some Panadol products moves to Spain and another 82 will be lost in a cost-cutting drive.
Tony Kelly, Unite regional officer, said further talks with GSK management are planned to try to prevent compulsory redundancies.
"This is a very difficult day for workers who have contributed without fail to the continued profitability of the company," he said.
"We will work hard to soften what is a terrible blow to those affected and to Dungarvan."
GSK said it will reorganise manufacturing operations in Dungarvan to ensure long-term success and pledged to keep producing three of the key growth brands - Panadol, Poligrip denture paste and NiQuitin Replacement Therapy patches.
Mike Willison, vice-president and site director, said the aim was to secure the plant's future for the long term.
"Although the site remains strategic within our network we must continue to further control our cost base and be more flexible and responsive to the global market needs," he said.
GSK took the decision on redundancies after a six-month examination of operations in Dungarvan, one of the company's largest sites supplying healthcare products to 64 markets worldwide.