Heath Ledger’s sister issued him tragic warning day before his death

Warning: This article contains discussion of drug use which some readers may find distressing.

Next month will mark 18 years since we lost Heath Ledger and sadly not even a warning from his sister could save the beloved actor from his tragic death.

Ledger was just 28 when he died but he had already won over viewers with his performances in Brokeback Mountain, 10 Things I Hate About You and A Knight's Tale.

However, he will always be renowned for his role as the Joker in the Dark Knight trilogy, with many fans of the DC films regarding him as the best to ever play Batman's infamous nemesis.

Of course, the Australian actor would become one of the few people to win a posthumous Oscar, as he won the award for Best Supporting Actor after portraying the Joker in The Dark Knight.

Heath Ledger produced some legendary performances before his death in 2008 (Jemal Countess/WireImage)

Ledger well and truly threw himself into the role, even locking himself inside a hotel room with nothing but DC comics and a journal which he kept in character.

He tragically passed away from an overdose in January 2008, just months after completing filming.

A coroner later confirmed that the star's overdose was very much accidental, as he was found to have died due to 'acute intoxication' following the consumption of a mixture of prescribed medications.

Sadly, this came just a day after his sister Kate had sent him a warning about the number of medications he was on, with their father Kim recalling the message she had sent him.

Kim told news.com.au: "The last conversation Kate had with him was this discussion about his medications and she warned him, 'You can’t mix drugs that you don’t know anything about'."

Despite him responding that he would 'be fine', Ledger was discovered by his massage therapist the next day and he was pronounced dead in the afternoon after attempts to resuscitate him sadly failed.

Ledger's family accepted his Oscar on his behalf in 2009 (GABRIEL BOUYS/AFP via Getty Images)

"It just put his whole system to sleep I guess," Kim explained after the coroner made his conclusions back in 2008.

He added: "It was a one-off thing. That's what killed us, because he was warned by his sister the night before: 'You shouldn't mix what you're taking for pneumonia with your Ambien'.

"He was a young guy that traveled all the time for work. Even as a two-year-old, he hardly ever slept. He was trying to work and travel and do everything in a short space of time."

Kim concluded: "Heath mixed a couple of drugs together with sleeping tablets and he's gone forever."

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