ER veteran Gloria Reuben is just what the doctor ordered!

The former ER star – who made history by playing one of the first HIV-positive characters on TV during the NBC drama’s first six seasons – is returning for a badly needed ratings boost, The ENQUIRER has learned.

“If anyone can teach this younger cast how it’s done, it’s her,” a set insider told The ENQUIRER. As the Emmy-winning medical drama heads into its 14th season, producers fear it’s in danger of losing steam, said the source.

“They’re hoping Gloria’s return will draw back older viewers who have strayed from the young, hipper cast,” the source explained.

The 43-year-old actress played Jeanie Boulet, a physicians’ assistant who contracted HIV from her cheating husband.

Later in the series, Jeanie adopted an HIV-positive baby – and for her return to County General, producers have ordered up an emotional story line.

“Terrified that her son’s HIV has developed into full-blown AIDS, Gloria’s character takes her son to County General for testing. It’s gut-wrenching, especially for fans who grew to love her,” the insider added. As part of her story line, Gloria’s character also runs an HIV clinic, the source said.

After leaving ER with two Emmy nominations, Gloria starred in TV’s The Agency. She’s also had guest stints on Law & Order: SVU and Numb3rs – and she’s already making an impact on the ER set.

“The cast and crew love Gloria. She’s a real pro who acts like she’s one of the gang,” said the insider. “It’s not certain how long she’ll be back, but everyone on the show is hoping it’s for good.”