According to bassist Adam Duce, "After considering the seriousness of Phil's health condition, we all feel that skipping these last two shows is the best thing to do... getting Phil back to the States to get checked out is the most important thing right now."
He added: "Phil is very sorry about it, but we all feel that his health and safety is most important at this time."
It is the second time in four months Demmel has collapsed on stage - on 17th August he complained of feeling light-headed moments before passing out onstage in Virginia.
At the time it was blamed on dehydration - but Demmel said afterwards it was caused by a condition called Cardiogenic Syncope, in which the heart heart fails to pump enough blood causing him to faint.
Machine Head plan to resume touring this week in Los Angeles for the first of two Metallica shows at The Forum.