An inhalation device, assembly or system can include a kit and a pharmaceutical composition. The device can be adapted for administering therapeutic aerosols to pediatric patients, including neonates, infants or toddlers. The device can further include a vibrating mesh aerosol generator that can be insertable into a flow channel of the inhalation device through a lateral opening, and a valved face mask. The device can be connectable to a gas source through which a gas, such as oxygen, can be received into the flow channel at a low flow rate.