The tour was set to hit six more European cities but according to the Ozzfest people Zakk Wylde is suffering from "mental and physical exhaustion". Possibly the hardest working man on the tour Zakk has to play two sets a day, one with Ozzy and one with his own band Black Label Society and apparently it proved to be too much for the beer guzzling axeman. 

The North American Ozzfest is still set to go off as planned but European fans are out of luck. 

more on Ozzfest