An ambulance was called to the 35-year-old rapper's Calabasas home on Thursday when Montana started suffering from "stomach pains, nausea and an elevated heart rate", TMZ reports.
L.A. County Sheriff's deputies had actually been called to the house at 1.30pm over reports of a suspected robbery - which turned out to be a false alarm - but they were so concerned by French's condition that they summoned an ambulance to take him to hospital.
He was quickly transported to a San Fernando Valley hospital, where he was treated with IV fluids.
This is the latest upset for Montana, who was sued in August over a "vicious" dog attack.
The rapper became the subject of a new lawsuit after Daniel Banuelos, who installed a security-camera system at French's Calabasas home, alleged that his German Shepherd Zane "violently attacked and viciously" bit him.