SIPTU has said it is engaging with management at Teva Pharmaceuticals over threatened redundancies at its plant in Waterford.
The union has said the move could impact up to 19 of its members at the pharmaceutical manufacturer.
Teva is one of the largest employers in the south east region with a workforce of around 700 people.
The company's website states that it provides "high-quality medicines that improve the health of people around the world, both prescription medications as well as over-the-counter treatments."
SIPTU Manufacturing Divisional Organiser, Neil McGowan has said: "The company has recently announced its intention to implement a number of redundancies at the plant.
"This is expected to impact the positions of up to 19 SIPTU members. Union representatives have begun the statutory period of consultation with management on this proposal.
"As always, SIPTU will aim to protect the jobs of our members and ensure they are adequately represented in this situation," Mr McGowan added.
Meanwhile, a spokesperson for the company said Teva can confirm that it has initiated a "consultation process" at its Waterford site "following changes in our business needs".
The spokesperson said: "We are engaging closely with employee representatives, and those potentially impacted, and are committed to conducting this process responsibly and transparently with our colleagues."
Teva Pharmaceuticals is headquartered in Tel Aviv, Israel and last year, the main Irish arm of the company paid out dividends of €617.9 million to its parent company.
The latest accounts for Norton (Waterford) Ltd also showed that it recorded a 31% increase in pretax profits to €13.30 million.
However, the increase came as revenues at the Waterford-based firm declined by 8% to €435.81 million.
