By Mattea BubaloBBC News
Getty ImagesPerry was a fan favourite as Chandler Bing in FriendsActor Matthew Perry's death was an accident caused by the "acute effects of ketamine", medical officials in Los Angeles have confirmed.
The star was found unresponsive in the pool of his LA home in October, but a post-mortem examination was inconclusive at the time.
Drowning was listed as a contributing factor in his death.
He was best known for playing the wise-cracking Chandler Bing in the sitcom Friends.
The show followed six young friends living in New York City and aired from 1994 until 2004. Its finale was watched by 52.5 million in the US, making it the most watched TV episode of the 2000s.
At the height of his fame, Perry was battling with addiction to painkillers and alcohol, and attended rehabilitation clinics on multiple occasions.
In 2016, he told BBC Radio 2 that he could not remember three years of filming during Friends, because of drink and drugs.
After attempts at treatment, he wrote in his memoir that he had been mostly sober since 2001 - "save for about 60 or 70 mishaps".
Other contributing causes of the 54-year-old's death were given as coronary artery disease and the effects of buprenorphine, which is used to treat opioid use disorder, the LA County medical examiner said in a statement.
"At the high levels of ketamine found in his post-mortem blood specimens, the main lethal effects would be from both cardiovascular overstimulation and respiratory depression," senior deputy medical examiner Raffi Djabourian wrote, according to the Press Association.
"Drowning contributes due to the likelihood of submersion into the pool as he lapsed into unconsciousness; coronary artery disease contributes due to exacerbation of ketamine induced myocardial effects on the heart."
He was found unresponsive at his home on 28 October, and paramedics pronounced his death when they were called to the scene.
A day later, the medical examiner's office updated its file to say his case had been deferred, which usually means that the post-mortem is complete but more detail is needed.
His fellow Friends actors paid tribute to Perry in the weeks following his death, with actress Jennifer Anniston - who played Rachel in the sitcom - writing that "having to say goodbye to our Matty has been an insane wave of emotions that I've never experienced before".
David Schwimmer, who played Ross, thanked Perry "for 10 incredible years of laughter and creativity".
He was laid to rest at an LA cemetery following a private funeral, US media reported in November.
Films he starred in included crime caper The Whole Nine Yards and sequel The Whole Ten Yards with his friend Bruce Willis. He played the lead in romantic comedy Fools Rush In with Salma Hayek, and he played the older Zac Efron in 17 Again.
In 2016, he also wrote a play called The End of Longing - which the Times noted "explores his characters' search for love and commitment and the damage that can be wrought when those things continue to be absent from life".
Watch: Matthew Perry appeared on Newsnight in 2013 to debate addictionBBC in other languagesInnovationncG1vNJzZmivp6x7o67CZ5qopV%2Bjsri%2FjrCmq6SUYsK0ecKapZqckWKDeIOSbWpybw%3D%3D