Robert Cosby Jr. was administered Narcan before police reached him … this according to dispatch audio.

The son of ‘Real Housewives of Salt Lake City’ star Mary Cosby was not conscious and not breathing Monday, according to the dispatcher … who then says Robert had been given the opioid overdose countermeasure Naloxone — brand name Narcan — already.

Three units were en route to Cosby … however, we know that once they arrived there was nothing they could do. Page Six was first to report on the dispatch audio.

We broke the story … emergency medical services received a call about someone experiencing a “full arrest / medical emergency.” EMS pronounced Robert dead at the scene.

Robert had a stressful few months prior to his death … including an arrest for assault in September and his wife filing for divorce a few months later. He was also arrested for DUI in 2022, a charge to which he later pled guilty.

Mary and Robert had one memorable moment on the show … an emotional conversation that took place after Robert got married without telling his mom.

Robert was 23.