A single-use container for fluid products, comprising: - a containment body for a fluid product, provided with a neck ending in a dispensing mouth , and with a shoulder arranged below the neck and having a greater diameter than said neck ; - a closing means which in an initial configuration is joined to said containment body along a predetermined breaking line to close the dispensing mouth and in an opening configuration, obtained by tearing said predetermined breaking line , is separated from said containment body to open said dispensing mouth ; - an opening key which in the initial configuration is slidingly fitted onto the closing means and is rotationally disconnected therefrom and in a working configuration is prismatically rotationally engaged with said closing means to put pressure thereon and remove the closing means from said containment body to obtain the opening configuration; said opening key comprising a gripping portion and a connection portion having an end edge , wherein in the initial configuration the connection portion extends up to the beginning of the shoulder , and wherein , when the end edge meets the shoulder of the containment body , due to an axial compression force acting on the opening key , it deforms elastically, thus generating an upward thrust force in the direction of the prismatic decoupling between the opening key and the closing means ; - at least one axial counterthrust means for the prismatic decoupling between the opening key and the closing means , activated by an axial compression force acting on the opening key , wherein the end edge is the axial counterthrust means; characterized in that the end edge of the connection portion is cylindrical, uniform and free from interruptions. - a containment body for a fluid product, provided with a neck ending in a dispensing mouth , and with a shoulder arranged below the neck and having a greater diameter than said neck ; - a closing means which in an initial configuration is joined to said containment body along a predetermined breaking line to close the dispensing mouth and in an opening configuration, obtained by tearing said predetermined breaking line , is separated from said containment body to open said dispensing mouth ; - an opening key which in the initial configuration is slidingly fitted onto the closing means and is rotationally disconnected therefrom and in a working configuration is prismatically rotationally engaged with said closing means to put pressure thereon and remove the closing means from said containment body to obtain the opening configuration; said opening key comprising a gripping portion and a connection portion having an end edge , wherein in the initial configuration the connection portion extends up to the beginning of the shoulder , and wherein , when the end edge meets the shoulder of the containment body , due to an axial compression force acting on the opening key , it deforms elastically, thus generating an upward thrust force in the direction of the prismatic decoupling between the opening key and the closing means ; - at least one axial counterthrust means for the prismatic decoupling between the opening key and the closing means , activated by an axial compression force acting on the opening key , wherein the end edge is the axial counterthrust means; characterized in that the end edge of the connection portion is cylindrical, uniform and free from interruptions. <EOS>