GSK is to close its manufacturing plant in Sligo by 2021,with the loss of 165 positions.
Staff have been informed that the skincare manufacturing plant in Sligo is to be phased out over the next three years, and will close by the end of 2021.
Just over two years ago, the company created 50 jobs at the Sligo plant, but says demand for products made at this facility has not grown in line with previous expectations, due to the highly-competitive market.
GSK has been in Sligo for the past 43 years, and its plant is a dedicated supply site for the company's Stiefel skincare products.
In a statement to Midwest News, GSK said a number of alternatives for the Sligo plant had been evaluated but, none of them were considered feasible without significant further investment.
The statement says the company's immediate priority is to support their employees through this difficult period.
GSK's other operations in Ireland (manufacturing sites in Cork and Dungarvan, and commercial operations in Dublin) are not affected by this proposal.