- There are three basic types of inhaler devices that deliver medications. The most common is the metered dose inhaler (MDI). This uses a chemical propellant called hydrofluoralkane (HFA) to push the medication out of the inhaler. Nebulizers deliver fine liquid mists of medication through a tube or a "mask" that fits over the nose and mouth, using air or oxygen under pressure. Dry powder inhalers (DPIs) deliver medication without using chemical propellants, but they require a strong and fast inhalation.
With inhaled medications, the medicine is delivered directly to your bronchial tubes, helping to open your airways. Also, these medicines have fewer side effects compared to others that are taken by mouth or by injection.