Methods, systems, and devices are described for sealing a nebulizers liquid reservoir. A nebulizer liquid reservoir may be provided that is in fluid communication with an aerosol generator. The nebulizer liquid reservoir may have an open end and a headspace. A cap may be placed on the open end of the nebulizer liquid reservoir, wherein the cap partially fills the headspace of the nebulizer liquid reservoir. The cap can include a plunger that passes through the cap and allows for air to escape from the headspace of the nebulizer liquid reservoir through the cap. The cap can seal the nebulizer liquid reservoir by actuating the plunger to a locked position. The plunger may create an airtight seal with the cap when in the locked position. An ambient pressure may be maintained in the sealed nebulizer liquid reservoir until a portion of the liquid is dispensed.
