Angus Cloud died from an accidental overdose of a lethal combination of drugs in July.

The 25-year-old was found unresponsive at his family home in Oakland.

Sweeney, who is currently starring in the comedy Anyone But You, said the Europhia cast "were constantly on the phone with each other crying" when they found out about Cloud's death, in an interview with Glamour.

HBO show Euphoria follows a group of school students in the US and often covers headline-grabbing storylines, including addiction and sexual assault.

Cloud played drug dealer Fezco in the show.

"I don't think it'll truly feel real or hit me until we're filming and I won't see Angus on set," Sweeney said.

"[At least] when we are filming, all of our eyes are on each other and we're there for each other, just in a different way than we're able to when we're all in very separate places in the world.

"It's really interesting when someone passes away in our industry, because they're still alive in so many forms."

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After he passed away, Sweeney left a tribute to Cloud on Instagram, writing: "You will be missed more than you know, but I'm so blessed to have known you in this lifetime, and I'm sure everyone who has ever met you feels the same.

"This heartache is real and I wish we could've had one more hug and 711 run. All my love is with you."

Euphoria, which also stars Zendaya, is due to start filming again next year.