Actress Emmy Rossum plays Fiona Gallagher, the oldest sibling who takes on the role of mom, while her dad, Frank -- played by William H. Macy -- is a drunk. "Shameless," now in its fourth season, is adapted from a long-running, award-winning British television drama of the same name.
For much of the show's run, Fiona led the dysfunctional, low-income family of five and even became a legal guardian to her siblings. Yet, now the character finds herself in serious trouble.
On "CBS This Morning," Rossum, said that she used to get "a lot of love" from fans of the show, but since her character has been in "such a downward spiral" it's been different.
"I was at Carnegie Deli and a guy came up to me and was like, 'Coke whore!' And kept walking, so it's definitely intense," she said.
In an episode that aired earlier this year, Fiona snorts cocaine left by her ex-boyfriend's brother. Her two-year-old brother Liam consumes the remainder of the drug and is found unconscious. While he's being treated in the hospital Fiona is arrested and ends up in jail.
"She's been kind of the core of this lower-income family from Chicago for a long time. Parents are M.I.A," she said. "She's kind of trying to raise all of her siblings by herself and this year she's kind of struggling with some substance abuse problems that ... she's kind of genetically predisposed to having."
While the drug scenes on "Shameless" might look realistic, Rossum said she's "never done one" in her actual life and used milk powder to practice snorting.
"(The milk powder is) going somewhere into your brain cavity. It's not good. I told them they could have two takes per nostril and that was it," she said. "I was putting a limit on it."
Rossum also discussed the show's success, saying "it's dark, but there's a lot of humor to it."
"I think we deal with things in a kind of very brazen way. There's nothing we're scared of. We kind of push the limits," she said. "At the core it's really about a family and loyalty. And that's why people actually care about the characters and invest in them the way they do."
A few months ago on "CBS This Morning" Macy called Rossum, "the spiritual center of the show." When asked about his comments, Rossum pushed the compliments back on him.
"He's a wonderful actor. It's really fun to work with him," she said.
"Shameless" is being picked up for a fifth season on Showtime, a division of CBS.
To see Emmy Rossum's full interview, watch the video in the player above.