McGraw collapsed after he finished singing one of his biggest hits, "Humble and kind". At some point, according to a video filmed by an audience member, Hill returned to the stage, reports washingtonpost.com.
"We have all been a little bit dehydrated travelling so much, and he's been super dehydrated," said McGraw's wife Faith Hill, also a singer.
"And I apologise, but I made the decision that he cannot come back out on stage."
The crowd started cheering "Get well, Tim! Get well, Tim!" as Hill urged everyone to "drink water".
His publicist released a statement that read: "Tim McGraw was suffering from dehydration in Dublin this evening at the C2C show. He was attended to by local medical staff on-site and will be fine. He and Faith thank everyone for their love and support and look forward to seeing their Irish fans again soon."
Before leaving, Hill promised to be back.
Dublin is listed as the husband-wife team's last tour stop for a while. They are scheduled to resume their tour on May 31.
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