Pete Davidson In Rehab, Struggling With Mental Health

Pete Davidson has entered rehab  ... and we're told his mental health has everything to do with it.

TMZ has confirmed, Pete's now in rehab due to his recent struggles with his mental health, according to sources familiar.

We're told he suffers from borderline personality disorder and PTSD. Page Six was the first to report the news.

A close friend of Pete's tells us his girlfriend, Chase Sui Wonders, and his other friends are rallying behind him and are by his side ... telling us Pete periodically checks himself in to work on these issues and better himself.

Pete's been a bit of an open book when it comes to his battle with his mental health ... often laying it all out there during his 'Weekend Update' segments on the long-running variety series.

He also got candid during a 2021 "Actors on Actors" Variety interview -- telling Glenn Close he felt like the weight of the world was lifted off his shoulders when he was diagnosed with BPD.

TMZ broke the story, PETA recently came after Pete for buying a dog from a pet store instead of getting it from a shelter ... and he fired back with an extremely rough, emotional voice mail, listing off the reasons why he had to get the pup through that route.