The Irish Coastal and Marine Research Centre has said while there have been reports of the Portuguese man-o-war in Wexford and Waterford, it cannot confirm any official sightings.
Marine Biologist Dr Tom Doyle has urged anyone who believes they have seen a Portuguese man-o-war to report it straight away.
He said the most common jellyfish on Irish shores is the barrel jellyfish and while its looks big and frightening, Dr Doyle said it is "quite harmless".
He added that the lion's mane jellyfish has also been spotted off Dublin and Louth. This jellyfish can inflict serious injury on swimmers and people should be vigilant, he added.
