However, Tony McGahan and the Munster management are hopeful that the influential flanker will be ready in time for the resumption of the province's Pool 1 campaign.
But there is bad news concerning fellow back rower Denis Leamy who will need an operation to repair damage to a hip that has been bothering him for some time.
The Cashel man faces up to four months on the sidelines - ruling him out of Ireland's plans for the fast-approaching RBS 6 Nations.
Leamy joins another Tipperary native on Munster's injury list. Young flanker Tommy O'Donnell is nursing a knee injury which will keep him out of action for up to six weeks.