Pulmicort is a brand-name prescription drug that contains the active drug budesonide, which belongs to a class of drugs called corticosteroids. It is used to prevent difficulty breathing, chest tightness, wheezing, and coughing caused by asthma. Pulmicort is a maintenance treatment, which means that it is taken every day to help manage asthma symptoms. It works by reducing inflammation in the lungs, which controls asthma and prevents asthma attacks. Pulmicort comes in two forms: Pulmicort Flexhaler, which is a dry powder that’s taken as puffs using an inhaler called the Flexhaler, and Pulmicort Respules, which is a liquid that comes inside small plastic containers called respules and is taken using a nebulizer. Pulmicort must be used regularly to be effective and does not work right away. It should not be used to relieve sudden asthma attacks. If an asthma attack occurs, use your quick-relief inhaler as prescribed.