Sexton underwent return-to-play protocols after the incident in the loss but has not been cleared to play.
The news comes after Sexton hit out at a French doctor who claimed the five-eighth had suffered approximately 30 concussions in his career, with neurologist Dr Jean-Francois Chermann subsequently apologising.
Billy Burns will start instead for Andy Farrell's side, which lost 21-16 in Cardiff, with Jamison Gibson-Park also in the XV as scrum-half Conor Murray sits it out with a hamstring injury.
The captain's armband goes to Iain Henderson for the first time, with the suspended Peter O'Mahony replaced by Rhys Ruddock following his red card in the Welsh capital.
James Ryan also sustained a blow to the head in that game and, like Sexton, will be absent this weekend.