A hand-held compressor nebulizer suitable for vaporizing liquid medication, comprising a casing (2) and a motor-driven air pump (5). The nebulizer includes a liquid medication supply unit and a vaporizing unit. The vaporizing unit comprises upper and lower vaporizing chamber (9 and 6), said lower chamber (6) including a reservoir (12) for liquid medication from the liquid medication supply unit. The vaporizing unit includes a hollow conical member located within lower chamber (6) and defining an internal conical passage (11) having a relatively smaller upper end and a relatively larger lower end, said lower end being in communication with the air pump (5) for receiving an upward airflow produced by the air pump (5). The airflow increases in speed in the upward direction and creates a negative pressure upon exit from the upper end of the conical passage (11). The vaporizing unit further includes a vaporizing jacket (7) having a tapered interior and disposed around the conical member to form a narrow gap with the conical member. The gap has an upper end in the vicinity of the upper end of the conical passage (11) and a lower end in communication with the reservoir (12), such that said negative pressure can cause, by way of suction, liquid medication in the reservoir (12) to move upwards along the gap and subsequently be vaporized by the airflow upon exit from the upper end of the gap.