In the final minutes of the Serie A victory on Wednesday evening, Calabria had a nasty collision with Massimo Gobbi and came off far worse.
He was on the ground for some time before being stretchered off with his head and neck immobilised.
A statement from Milan confirmed Calabria was taken to hospital for tests, which showed head and facial trauma.
He will remain under observation at the clinic in Verona, but is conscious.
“There was blood coming from his nose, but he did speak and waved at us,” explained teammate Alessio Romagnoli on Sky Sport Italia.