Montelukast is also used before exercise to prevent breathing problems during exercise (bronchospasm). This medication can help decrease the number of times you need to use your rescue inhaler. Montelukast crosses the placenta into the fetus following oral administration to animals, but there have been no adequate studies in pregnant women to determine the effects on the fetus. MONTELUKAST is used to prevent and treat the symptoms of asthma. It is also used to treat allergies. Do not use for an acute asthma attack. The lowest GoodRx price for the most common version of montelukast is around $3.30, 96% off the average retail price of $109.07. SINGULAIR® (montelukast sodium) Tablets and Oral Granules. DESCRIPTION. Montelukast sodium, the active ingredient in SINGULAIR, is a selective and orally active leukotriene receptor antagonist that inhibits the cysteinyl leukotriene CysLT 1 receptor. MONTELUKAST is used to prevent and treat the symptoms of asthma. It is also used to treat allergies. Do not use for an acute asthma attack. The lowest GoodRx price for the most common version of generic Singulair is around $2.97, 97% off the average retail price of $109.07. How to use Singulair. Read the Patient Information Leaflet if available from your pharmacist before you start taking montelukast and each time you get a refill. Montelukast is not expected to be harmful to an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant during treatment. It is not known whether montelukast passes into breast milk or if it could harm a nursing baby. Montelukast sodium Images. What does Montelukast sodium look like? Note: Multiple pictures are displayed for those medicines available in different strengths, marketed under different brand names and for medicines manufactured by different pharmaceutical companies. What other drugs will affect montelukast (Singulair)? Other drugs may interact with montelukast, including prescription and over-the-counter medicines, vitamins, and herbal products. Tell each of your health care providers about all medicines you use now and any medicine you start or stop using. View images of Singulair and identify pills by imprint code, shape and color with the Drugs.com Pill Identifier.