Jessica Szohr spent six seasons wearing the trendiest fashions on “Gossip Girl,” that soapy CW drama that profiled the scheming and bed-hopping of a group of privileged teens on the Upper East Side.

Now as a street-smart ER nurse on new USA Network drama “Complications,” the 30-year-old actress’ wardrobe is mostly hospital scrubs.

“It couldn’t be more different,” Szohr says of “Complications,” whose fourth episode premieres Thursday at 9 p.m. “ ‘Gossip Girl’ was this pop culture, fashion show that New York was a part of, and we were all young. Now everyone [on this show is] married with kids and in Atlanta and it’s … a much more mature role, which I love.”

On “Complications” — which averaged 2.8 million viewers for its June 18 premiere — Szohr’s character, Gretchen Polk, gets pulled into Atlanta’s gang underworld after her colleague, Dr. John Ellison (Jason O’Mara, “Vegas”), saves the life of a young boy during a drive-by shooting.

“I don’t feel like it’s a medical show. It’s a crime thriller and we happen to be a nurse and a doctor [who are] put into this crazy gang world,” she says. “As the series goes on I’m actually outside of the hospital more than I’m in.”

When John’s connection to the boy complicates his personal and professional life, he enlists the help of Gretchen — the kind of nurse who sneaks cigarettes while on the clock, fiercely defends a patient with an abusive boyfriend and isn’t above bribing a hospital attendant with prescription drugs to tamper with medical records.

“With Gretchen and John, I say they’re like Batman and Robin [because] they both need each other even though they don’t see eye to eye on a lot of things,” Szohr says. “They’re both trying to do the right thing, but they don’t always go about it the right way at all. He’s very structured … and she’s in the moment.”

Although there won’t be any romantic drama between the two main characters (Gretchen is gay), Szohr promises plenty of crazy complications to come during the eight-episode season — its initial premise was actually inspired by creator Matt Nix’s (“Burn Notice”) own experience of having a gang member break into his LA home 10 years ago, then having to go to court and testify against him.

“That’s what makes the series for me as an actor even better,” Szohr says. “This was not just drawn from imagination; this was actually something that went on and then [Nix] used his imagination to make it brilliant.”