Systems, methods (150), and devices are described for heating nebulizer adapters (100, 700). In certain embodiments, a nebulizer adapter includes a cup (102) having an interior wall (104) defining a gas mixing chamber (106, 706), an exterior wall (108), and a fluid cavity (110, 710) disposed between the interior wall and the exterior wall. The nebulizer adapter also includes an inlet port (112) having a fluid lumen (114) in fluid communication with the fluid cavity and a breathing gas inlet lumen (116) in fluid communication with the mixing chamber. The nebulizer adapter further includes an outlet (118, 718) having a breathing gas outlet lumen (730), and a drain port (119) in fluid communication with the mixing chamber and having a drain lumen that passes from the interior wall to the exterior wall of the cup.