Cormac Izuchukwu has been called up to replace Tom Ahern, while Robert Baloucoune will continue to be assessed over the coming days after being withdrawn at half-time in Ulster’s defeat away to Scarlets.
Jack Boyle sustained a leg injury during Leinster’s victory over Connacht and Connacht’s uncapped prop Billy Bohan will join the training camp in Portugal.
Ireland will kick off the opening round of the Six Nations away to France on Thursday, 5 February (Kick-off 8.10pm Irish time).