Straight from TMZ, 'Kat Graham got way too high and ended up in the hospital ... TMZ has learned.

"The Vampire Diaries" actress and singer was visiting Two Bunch Palms Resort & Spa near Palm Springs last month when she allegedly started throwing up and passed out on a lawn. It wasn't food or booze that put her there though -- sources at the resort tell us she'd downed a cannabis brownie earlier in the day.

We're told Kat ran out of the resort's restaurant saying she didn't feel well and needed to go to the hospital. She puked, passed out, woke up and then hopped an ambulance to a hospital.'