Kim was right by Kanye's side as they showed up at West Hills Hospital in the San Fernando Valley. We're told Kanye had the flu and it got worse and worse, so he needed some Rx to make him feel better.

They were only there a short time ... and returned home where Kanye could rest.

Kanye's recently been tweeting about his sinus issues, but we're told it's unclear if they're related. He's been traveling nonstop lately.