A hand-held nebulizer converts liquid medication into a mist that can be inhaled. This method of treatment is useful for quickly loosening the muscles in the airway, freeing the lungs to do their work. Nebulizers are helpful in administering medication to infants and children who are not capable of using an inhaler themselves, especially for asthma treatment, according to the University of Virginia Health System (UVHS). UVHS also points out that administering medication this way can lead to more rapid improvement of symptoms. Follow your prescribing doctor's instructions for administering the medication. An overdose is possible using a nebulizer treatment.