Although the exact substance that poisoned Navalny is not yet known, it is believed to be a nerve inhibitor, Charité’s statement said. The hospital added that Navalny remains in an artificially induced coma but that “there is no acute danger to his life.”

He is being treated with Atropine, and “longer-term effects, especially to the nervous system, could happen at any point,” the statement said.

Navalny was stricken Thursday during a flight en route to Moscow from Siberia. His spokeswoman and others quickly claimed that the 44-year-old was the latest victim of a poisoning ordered by the state, a method used before in attacks linked to Russian agents.