Lehmann, 45, reported a swollen left calf to team medical staff before the fifth one-day international against India in Sydney on Saturday and was sent for a scan.
He was admitted to hospital for observation overnight during the India innings and will receive treatment for the condition.
“Darren is stable but he has been advised not to fly in the short term and will therefore require a layoff before he can return to coaching,” CA's chief medical officer John Orchard said in a statement.
Lehmann’s wife Andrea was told of the situation and the Australia players were informed after Saturday’s match which India won by six wickets to claim a consolation victory in a series they lost 4-1.
News that makes sense
Your trusted source for staying up-to-date with the world around you. Get free daily news updates and analysis, straight to your inbox.
Batting coach Michael Di Venuto will take charge of the side for the three-match Twenty20 series against India starting on Tuesday in Adelaide.
“Our first thoughts and concerns are obviously with Darren and his family -- health is more important than any cricket match," said Pat Howard, CA's executive general manager of team performance.
“We will assess the situation on the basis of medical advice and with Darren’s best interests in mind over the coming days.”
(Reporting by Ed Osmond in London; Editing by Ken Ferris)
