Marcia Gay Harden once described winning an Oscar as a double-edged sword: Although it is a wonderful honor, it does have its pitfalls.

“It’s disastrous on a professional level,” the actress said in 2003, a few years after winning a supporting actress Oscar for her portrayal of artist Lee Krasner, the wife of troubled painter Jackson Pollock, in Ed Harris’ “Pollock.” “Suddenly the parts you’re offered and the money become smaller. There’s no logic to it.”

Those drawbacks seem to have had minimal impact on Harden during the last few years, as she’s ridden a steady flow of featured roles in several high-profile projects. She has injected her blend of warmth and toughness to recent films (“Grandma”) and vehicles such as HBO’s “The Newsroom,” ABC’s “How to Get Away With Murder” and NBC’s “Law & Order: Special Victims Unit.” She scored a Tony Award in 2009 for lead actress in a play for “God of Carnage” and last year played Christian Grey’s mother in the hit film version of “Fifty Shades of Grey.”

For all her accomplishments, Harden, who costarred in ABC’s short-lived “Trophy Wife” in 2013-2014, has rarely found herself in the leading role. It’s a pattern that almost repeated itself when she was cast in CBS’ new medical drama, “Code Black,” premiering Sept. 30.

But when producers realized that the original lead of the show, Maggie Grace, was not working out, they made a change, and Harden is now heading the “Code Black” ensemble, taking on the role of Dr. Leanne Rorish, the residency director of a hospital emergency room in Los Angeles.

Though she has done only a handful of episodes, Harden, 56, is already calling “Code Black” a career highlight. “This is some of the hardest and most interesting work I’ve ever done. The cast is fantastic, and the writing is sublime.”

The series was inspired by an award-winning documentary from physician Ryan McGarry exploring the chaos of the country’s busiest emergency department at Los Angeles County-USC Medical Center. The term “code black” refers to the moment when the influx of patients is so great that it overwhelms hospital staff and not everyone can be treated properly.

McGarry is an executive producer of “Code Black,” working with show runner and executive producer Michael Seitzman.

Seitzman and McGarry said “Code Black” will be distinct from other medical dramas because of its realism and attention to detail. Actual trauma nurses work alongside the actors on and off camera and often give instructions during the frantic treatment scenes. The series has bloody and graphic moments — one life procedure in the pilot may be tough for some viewers to watch.

“It’s authenticity with specific intent, to show the humanity behind the chaos,” said McGarry.

Harden said she felt a connection to her role as Dr. Rorish: “She is a teacher. She wants the younger generation to be the best equipped and do the best job they can. She has suffered loss. She is compassionate.”

The role has had its share of challenges. Harden, along with the rest of the cast, had to attend medical “boot camp,” held in early March at Los Angeles County-USC Medical Center. Eight stations manned by trauma nurses and supervised by McGarry were set up and the main cast, as well as 70 extras, were instructed in emergency room procedures, using equipment that would be seen in the series.

“There’s so much jargon, and we have to look natural while doing it,” Harden said. “Putting on gloves and making it look smooth. We have to make it look natural to the audience without being frantic.”