A switchable adapter for a suction tube has a manifold, a switching base rotatably connected to a pivot portion of the manifold, an air-tight component mounted between the pivot portion of the manifold and the switching base, and a cover mounted on an end of the pivot portion. The switching base has two connecting tubes. When the switching base pivots relative to the pivot portion of the manifold, the connecting tubes alternatively communicate with the manifold by rotation of the switching base. Thus, the switchable adapter is switched to allow the suction tube to suck sputa out of a trachea of a patient.
