Montelukast sodium is a medication used to treat asthma, allergic rhinitis, and exercise-induced bronchoconstriction. It works by blocking leukotriene receptors, which are involved in the inflammatory response that causes asthma and allergies. This drug is usually taken orally in tablet or granule form. It is important to note that montelukast is not a rescue medication for acute asthma attacks, and it should not be used to treat an asthma attack that has already started. It is intended for regular use as a preventative treatment to reduce the frequency and severity of asthma symptoms. Montelukast sodium is available under various brand names, including Singulair, Montair, and Montecip.