The head of a printing company based in Londonderry has said raw material costs have gone up by as much as 15% in the last three months following the vote to leave the EU.
Nuprint Technologies, run by Gavin Killeen, is just 5km from the border with Co Donegal.
But Mr Killeen, the firm's managing director, said the dramatic weakening of sterling in the last year was part of running a business in a border region.
He also raised worries about possible future tariffs and custom controls on the border.
On currency, he said: "It affects me in that the vast majority of my raw material is manufactured in Europe somewhere.
"So whether I buy that in sterling or buy that in euro, that price has gone up, and it's gone up by about 10% or 15% in the last three months, which is a significant impact in that raw materials makes up a huge percentage of our business."
Nuprint provides packaging labels for the food and drink industry in Northern Ireland and the Republic. It started out supplying names for brands like Guinness, Magners and Harp.
But Mr Killeen said the firm had started seeking deals in the Republic to protect against currency changes. So, while taking a hit on importing raw materials, he's had some reprieve on sales into the Republic.
"That's an engineered place we've tried to get to, so that the business doesn't get exposed to fluctuations in currency like that. We forward buy, we hold and we'll watch what the markets are doing. Living in a border region, we just have to do that," he said.
And Mr Killeen, the president of Londonderry's Chamber of Commerce, said retailers in the city had also been coping with the changes in currency.
"Every single trader will have two tills - one with euro and one with sterling," he said.
He said that car parks of businesses in the city reflected how prevalent cross-border movements are.
"The cars are completely mixed and the owners of those cars come from both sides of the border," he said. "The people who are employed in the north, who live in the Republic, have had a 20% cut in their wages since this happened. That's a serious impact on some of those families. The people coming the other way have had a 20% increase."
He also said he was concerned about the potential for tariffs and customs controls on the border, and the potential for smaller border roads to be shut off.
"Some of my staff live in the Republic of Ireland," he said.
"They travel across that border and we hope that their route to work wouldn't be impeded in any way."