A nebulizer turns liquid medicine into a mist to help treat your asthma. They come in electric or battery-run versions. They come in both a portable size you can carry with you and a larger size that’s meant to sit on a table and plug into a wall. Both are made up of a base that holds an air compressor, a small container for liquid medicine, and a tube that connects the air compressor to the medicine container. Above the medicine container is a mouthpiece or mask you use to inhale the mist.