A switchable adapter for a suction tube has a manifold (1), a switching base (30) rotatably connected to a pivot portion (10) of the manifold (1), an air-tight component (2) mounted between the pivot portion (10) of the manifold (1) and the switching base (30), and a cover (4) mounted on an end of the pivot portion (10). The switching base (30) has two connecting tubes (311, 312) alternatively communicating with the manifold (1) by rotation of the switching base (30). Thus, the switchable adapter is switched to allow the suction tube to suck sputa out of a trachea of a patient.
