Actor Jim Carrey has said he is "shocked and deeply saddened" by the death of his Irish ex-girlfriend Cathriona White who was found dead in her home on Monday night, days after a second breakup from the actor.

The young make-up artist, 28, was discovered in her Los Angeles home by two friends who came to check in on her Monday evening and is said to have died from an apparent suicide.

"Ms White was found at 8.40pm local time on Monday, September 28, at her home in Sherman Oaks," said Los Angeles Assistant Chief Coroner Ed Winter.

"The final cause of death has not been confirmed, pending an autopsy."

TMZ report that White, originally from Cappawhite in Co. Tipperary, left a suicide note outlining her breakup with Carrey, 53, on September 24, on the same day that she posted a message to Twitter to say that she was “signing off”.

“Signing off Twitter, I hope I have been a light to my nearest and dearest,” she wrote.

It is believed she died from a drug overdose.

In a statement following her death, Carrey said, "I am shocked and deeply saddened by the passing of my sweet Cathriona.

"She was a truly kind and delicate Irish flower, too sensitive for this soil, to whom loving and being loved was all that sparkled. My heart goes out to her family and friends and to everyone who loved and cared about her. We have all been hit with a lightning bolt."

White and Carrey first met on a film set in late 2012 and dated for several months before breaking up in March 2013.

In May of this year, however, the couple reconnected and were seen together around New York before their recent split, with Carrey even pictured in White's home county jersey, Co. Tipperary. 

The actor was married twice before dating Cathriona. He was married to waitress Melissa Womer from 1987 to 1995 and to his "Dumb and Dumber" co-star Lauren Holly from 1996 to 1997.

He split from long-term girlfriend Jenny McCarthy in 2010. 

Jim Carey’s Irish ex-girlfriend Cathriona White was found dead in her home on Monday night, days after a second breakup from the actor.Instagram