Fine Gael's Joe Carey has resigned as a public representative, becoming the 16th party TD to announce their Dáil departure.
The Clare TD has been on sick leave since March 2023 and said his decision was based on medical advice.
The 49-year-old becomes the 16th Fine Gael TD elected in the 2020 General Election to announce they are not seeking re-election.
He said in a statement: "In the past year, I suffered a life-altering medical situation that I will be dealing with for the rest of my time on earth.
"While I would dearly wish to continue, my decision to step away is based on medical advice."
Mr Carey's sister Leonora will seek the party's nomination to replace her brother at the Clare constituency Fine Gael general election selection convention on 6 September.
Mr Carey entered politics in 1999 and was elected to Clare County Council at the age of 23.
He was first elected to the Dáíl in 2007 at the age of 31 and retained his seat in the 2011, 2016 and 2020 elections.
He said: "I have had the absolute privilege to serve for the past 25 years as a public representative, eight as a county councillor and 17 as a TD.
"I want to express my sincere thanks to my constituents who elected me to represent them on Clare County Council and in Dáil Éireann on six separate occasions."
In a letter to Fine Gael party members, Mr Carey also said he wanted to express his gratitude to them for campaigning with him throughout his political career.
"It is hard to believe but 25 years have passed since I was first elected to Clare County Council. It has been the greatest honour and privilege to be elected as a Fine Gael TD for County Clare at four successive general elections.
"My electoral success would not have been possible without your unwavering support."
Joe Carey is an outstanding champion for the people of Clare.
— Simon Harris TD (@SimonHarrisTD) August 26, 2024
Joe is putting his health first and he has all of our support in Fine Gael on that journey.
He leaves the Clare constituency ready for the future and is moving to his next chapter with all of our support. pic.twitter.com/SyqlnPNNaW
Fine Gael leader Simon Harris said Mr Carey was an "outstanding champion for the people of Clare".
The Taoiseach said on X: "Joe is putting his health first and he has all of our support in Fine Gael on that journey.
"He leaves the Clare constituency ready for the future and is moving to his next chapter with all of our support."
Mr Carey's decision to step down means 16 of the 35 TDs elected for Fine Gael in 2020 have now either already left politics or have confirmed they will not seek re-election to the Dáil.
The other 15 TDs who will not seek re-election are: Leo Varadkar, Simon Coveney, John Paul Phelan, David Stanton, Joe McHugh, Richard Bruton, Eoghan Murphy, Josepha Madigan, Ciarán Cannon, Brendan Griffin, Charlie Flanagan, Fergus O'Dowd, Paul Kehoe, Michael Creed and Michael Ring.
Across the board, 27 of the 160 TDs elected in 2020 have either already left or are not seeking re-election.
Additional reporting Fiachra Ó Cionnaith
