Montelukast, sold under the brand name Singulair among others, is a medication used in the maintenance treatment of asthma. It is generally less preferred for this use than inhaled corticosteroids. It is not useful for acute asthma attacks. Other uses include allergic rhinitis and hives of long duration. For allergic rhinitis it is a second-line treatment. Montelukast was approved for medical use in the United States in 1998. It is available as a generic medication. In 2020, it was the fourteenth most commonly prescribed medication in the United States, with more than 31 million prescriptions.