Collection device for collecting a breath sample from a user and containing target compounds to be characterized by an analysis device, including: o a mouthpiece for collecting the breath sample, configured to fully close the oral cavity of the user, and including: • a first face, referred to as the external face, intended to be located outside the oral cavity and at which an external orifice opens out: • a second face, referred to as the internal face, intended to be inserted into the oral cavity, opposite the external face along a longitudinal axis A L of the mouthpiece at which an internal orifice opens out which is connected to the external orifice by an internal duct; • a positioning base, including the internal face, and lower and upper contact surfaces (14a, 14b) which are intended to be in contact with users' teeth when they hold the mouthpiece in the oral cavity, the lower and upper surfaces being located on either side of the internal orifice along an axis referred to as the vertical axis; o characterized in that the mouthpiece includes a first tab, referred to as a retaining tab, which is configured to come into contact with the user's tongue and is formed by a thin plate oriented orthogonally to the vertical axis and extending from the internal face and from the side of the lower surface of the base along the longitudinal axis A L over a first predefined length L lc; o and in that the collection device includes a removable sampling tube, configured to be connected to the analysis device and able to be removed from the mouthpiece, passing through the internal duct, and extending along the longitudinal axis A L away from and opposite the retaining tab over a distance D that is less than or equal to the first length L lc, so that the retaining tab prevents any contact of the tongue with the sampling tube. o a mouthpiece for collecting the breath sample, configured to fully close the oral cavity of the user, and including: • a first face, referred to as the external face, intended to be located outside the oral cavity and at which an external orifice opens out: • a second face, referred to as the internal face, intended to be inserted into the oral cavity, opposite the external face along a longitudinal axis A L of the mouthpiece at which an internal orifice opens out which is connected to the external orifice by an internal duct; • a positioning base, including the internal face, and lower and upper contact surfaces (14a, 14b) which are intended to be in contact with users' teeth when they hold the mouthpiece in the oral cavity, the lower and upper surfaces being located on either side of the internal orifice along an axis referred to as the vertical axis; • a first face, referred to as the external face, intended to be located outside the oral cavity and at which an external orifice opens out: • a second face, referred to as the internal face, intended to be inserted into the oral cavity, opposite the external face along a longitudinal axis A L of the mouthpiece at which an internal orifice opens out which is connected to the external orifice by an internal duct; • a positioning base, including the internal face, and lower and upper contact surfaces (14a, 14b) which are intended to be in contact with users' teeth when they hold the mouthpiece in the oral cavity, the lower and upper surfaces being located on either side of the internal orifice along an axis referred to as the vertical axis; o characterized in that the mouthpiece includes a first tab, referred to as a retaining tab, which is configured to come into contact with the user's tongue and is formed by a thin plate oriented orthogonally to the vertical axis and extending from the internal face and from the side of the lower surface of the base along the longitudinal axis A L over a first predefined length L lc; o and in that the collection device includes a removable sampling tube, configured to be connected to the analysis device and able to be removed from the mouthpiece, passing through the internal duct, and extending along the longitudinal axis A L away from and opposite the retaining tab over a distance D that is less than or equal to the first length L lc, so that the retaining tab prevents any contact of the tongue with the sampling tube.