A liquid reservoir (100) of a nebulizer has a funnel portion (102) with ribs (103, 104) extending downwardly along a side wall towards a reservoir outlet (105). The ribs (103, 104) prevent the formation of air bubbles between the aperture plate and medication as any trapped air will be expelled along the geometry formed by the rib or groove and reservoir wall. Bubble formation is therefore prevented with only modification of the wall internal surface configuration of the reservoir.
