More than 50,000 smokers in Ireland are estimated to have switched to electronic cigarettes, with usage soaring in the last year.
But regulators and advertisers are still grappling with how to regulate the dramatic expansion of the new products, which are touted as a healthier alternative to conventional cigarettes.
E-cigarettes are battery-operated cartridges which heat up a special liquid to create a vapour that delivers a nicotine hit to users without the tar and carcinogens contained in normal cigarettes.
The Department of Health has just announced plans to regulate the sector, including a ban on sales to under-18s.
Health Minister James Reilly "is currently reviewing the evidence on the potential harm and the potential benefits of e-cigarettes before deciding the best approach to their wider regulation", a Department of Health spokesperson said.
But meanwhile, e-cigarette sales are soaring nationwide and e-cigarette company Rossport Pharmaceutical is to create 138 jobs at a new factory in Connemara, with backing from Udaras na Gaeltachta.
Its production director Tony Geraghty said that the Co Galway plant would allow it to export quality-guaranteed e-cigarettes all over Europe, which would allay consumer concerns about the contents of these products, which are currently mainly produced in China.
He estimated that 6-7pc of Irish smokers have already switched to e-cigarettes, amounting to over 50,000 people in total in the Republic but he said it was increasing rapidly.
Alex Pescar, of Ovale E-cigarettes, which has a store in Dublin's Gardiner Street and also supplies other retailers and online customers, said he also plans to begin manufacturing the liquid for e-cigarettes at a plant in Limerick shortly.
"There has been a huge increase in people using them," he said.
However, the Irish Cancer Society said that it could not recommend them to consumers until they were regulated.
"We're getting many queries about them but until we know exactly what's in the products, and what the long-term effects are, we cannot recommend them," said ICS Health promotion manager Kevin O'Hagan.
The Advertising Standards Authority of Ireland said it had asked the Department of Health for guidance on how e-cigarettes may be marketed, given a surge of queries from advertisers.