Mr Redmond’s support team leader, Noel Browne, said: “Steve will take a few days to rest and recover and won’t make any decisions until then.
“But you know Steve. He may try again, but this one is a real challenge.”
Mr Redmond, 48, set off from Carne Pier in Co Wexford at around 10pm on Wednesday, bidding to become the first person to swim from Ireland to Wales.
The epic swim was estimated to take 35 hours. Mr Redmond’s support team called the swim off at around 2.30am yesterday when he began to show signs of hypothermia.
Mr Browne said the temperature of the water was much colder than expected.
He added that Mr Redmond suffered several jellyfish stings and an upset stomach.
These all affected his ability to cope with the strong currents of the Irish Sea.
When it became clear that Mr Redmond’s physical condition was so poor so early in a marathon swim, and that the currents were pushing him in a south-westerly direction, the attempt was abandoned after four hours.
“Steve is disappointed but he’s fine,” said Mr Browne.
John Kearney, who was also travelling in the support boat, said the team made the right decision to end the attempt.
“Our main focus and concern was always Steve’s health and when he started displaying worrying signs of hypothermia we felt that with such a long swim ahead of him, it was not worth the risk,” he said.
“Steve has swum some of the most gruelling oceans and he knows that everything has to be right and you don’t take chances.
“It would have been an amazing accomplishment to add his incredible collection of endurance swims.”
Mr Redmond made history last year when he became the first person to complete the gruelling Seven Oceans Challenge.
He completed the final Oceans Seven swim — the treacherous Tsugaru Straight in Japan — on his fourth attempt.
He was undertaking the Ireland Wales swim to raise funds for the RNLI following the drowning of the three Bolger brothers off Waterford in June.
He has promised that the Ireland-Wales swim will be his last epic challenge.