Single-dose bottle for a fluid and a measuring cap for introducing a different soluble substance in said bottle, said substance being stored in a sterile manner in a breakable capsule housed inside said measuring cap at the mouthpiece portion of said bottle said measuring cap comprising a lower sleeve portion bottle for coupling with the neck of said bottle and an upper portion extending above said mouthpiece of said container and configured to make a seat for housing said capsule, said upper portion in turn comprising lateral walls for the at least partial lateral containment of said capsule and an upper roof portion for the upper containment of said capsule, said upper roof portion being movable by manual action of a user between a raised resting position, wherein it is in contact without compression against said capsule, and a lowered operating position wherein it compresses said capsule in a collapsed configuration.
