A de-agglomerator is provided for use with a breath-actuated dry powder inhaler for breaking up aggregates and micronizing particles of dry powder prior to inhalation of the powder by a patient using the inhaler. The de-agglomeratol includes an inner wall defining a swirl chamber extending along an axis from a first end to a second end, a dry powder supply port, an inlet port, and an outlet port. The supply port is in the first end of the swirl chamber for providing fluid communication between a dry powder delivery passageway of an inhaler and the first end of the swirl chamber. The inlet port is in the inner wall of the swirl chamber adjacent to the first end of the swirl chamber and provides fluid communication between a region exterior to the de-agglomerator and the swirl chamber. The outlet port provides fluid communication between the second end of the swirl chamber and a region exterior to the de-agglomerator, whereby a breath induced low pressure at the outlet port causes air flows into the swirl chamber through the dry powder supply port and the inlet port. The air flows collide with each other and with the wall of the swirl chamber prior to exiting through the outlet port, such that any powder entrained in the air flows is broken down and micronized.
