Fans were quick to sympathise with the star, who is known to put her all into every show she does.
'Get well soon,' one wrote, with another adding, 'You are only human and amazing, but everybody has limits on how much you can push yourself with this tour!!'
Another echoed, 'We all understand. Get better soon!'
The US songstress arrived in Aus last month with her husband Carey Hart, and two children - Willow Sage, 7, and Jameson Moon, 18-months.
We're wishing the star a speedy recoery!