Former New York City Mayor Rudy Giuliani is reinserting as an informal advisor President Donald Trump — this time offering medical advice for combatting the novel coronavirus.

Giuliani has been using his podcast to promote alternative treatments including, “a stem cell therapy that involves what he called “placenta ‘killer cells.’”

He has also emerged as a strong supporter of hydroxychloroquine, the anti-malarial drug that has shown some promise of treating COVID-19 but has yet to be tested in a large-scale, controlled clinical trial.

A Washington Post report labels Giuliani as a “personal science adviser to a president” and notes that the former mayor has been promoting the anti-malarial drug to Trump in one-on-one phone calls.

“He said he now spends his days on the phone with doctors, coronavirus patients and hospital executives promoting the treatment, which Trump has also publicly lauded,” the report reads.

Giuliani has since promoted his medical advice on Fox News, despite not having a medical background.

Dan Pfeiffer, formerly a senior adviser in the Obama administration, criticized Fox News for giving Giuliani a platform to promote unproven medical theories. Fox host Laura Ingraham, pictured interviewing Giuliani above, has also received criticism for spreading misinformation about the drug.

“It’s wild that the cable networks are broadcasting live as the President passes along unproven medical advice that he got from Rudy Giuliani,” Pfieffer tweeted. “They are facilitating a dangerous level of misinformation.”