Sienna Miller says Los Angeles is "the most medicated place" she's ever been to.
The actress has previously spent time in the American city but has decided it isn't where she wants to settle. Although she enjoys making movies she thinks her future lies in theatre, and doubts she will be jetting to the west coast of the US too often.
"I think I'm clearer about what I want to do," she told the British edition of Vogue magazine. "Everyone's on something [in Los Angeles]. It's the most medicated place, there's a whole massive market for really addictive drugs. I've been prescribed [painkiller] Vicodin when I didn't really need it. It's dangerous. I mean, it's prescription heroin really."
Sienna is currently expecting her first child with her partner Tom Sturridge. She has decided not to discuss her pregnancy too much as she prefers to keep some things quiet, but admits it has had a profound effect on her.
"I woke up feeling completely out of it. I feel a little bit like I don't know my own name literally, I don't know what is going on with my head," she laughed.
Sienna is reluctant to discuss her private life because she was one of the stars whose phone was hacked by the now defunct UK newspaper News of the World.
The actress gave evidence at the London based Leveson Inquiry, which is investigating allegations that some British publications routinely accessed people's voicemails.
Sienna discovered her emails had also been looked at and found the whole thing deeply disturbing. She accused loved ones of leaking information about her as she couldn't understand how certain things had become public.
The 30-year-old has discussed how upsetting that period in her life was.
"That level of scrutiny had a massive effect on me personally, on my career and my relationships, all of it. It was just a fishbowl," she said.
"It definitely impacted on all sorts of relationships trying to have a relationship while being watched and pursued is difficult for anyone I was freaked out constantly.
"Having a reputation as a tabloid person was not something I ever sought out. I had never given quotes. I'd always belligerently resisted that kind of attention. But to live with that level of paranoia which is what it felt like I think I was a nightmare to be around."