Carlos Santana is on the mend after suffering a medical emergency and being rushed to a hospital … but he’s going to have to scrap another show.

A rep for the legendary musician tells TMZ … Carlos has been discharged from the hospital and is resting in a hotel, but his show Wednesday night in Sugar Land, Texas has been canceled out of an abundance of caution.

We’re told dehydration was determined to be the main reason Santana collapsed Tuesday during a sound check at a venue in San Antonio.

TMZ broke the story … Santana was taken to a hospital after suffering a medical emergency, and his Tuesday show at the Majestic Theatre was postponed.

Carlos was scheduled to perform Wednesday at Smart Financial Centre in Sugar Land … but now that’s not happening.

He also has shows scheduled for Friday and Saturday in Oklahoma as part of his “Oneness” tour.

Carlos’ rep says he’s expected to be fine, though it’s unclear when he will be back onstage.