Do not use montelukast to treat an asthma attack that has already begun. It will not work fast enough to reverse your symptoms. Use only a fast-acting inhalation medication to treat an asthma attack. Talk with your doctor if any of your asthma medications do not seem to work as well in treating or preventing asthma attacks.
It may take up to several weeks of using this medicine before your symptoms improve. For best results, keep using the medication as directed. Talk with your doctor if your symptoms do not improve after several weeks of treatment.
Call your doctor right away if you feel that this medicine is not working as well as usual, or if it makes your condition worse. If it seems like you need to use more of any of your medications in a 24-hour period, talk with your doctor.
If you already take this medication to prevent asthma or allergy symptoms, do not use it for exercise-induced bronchoconstriction.
Call your doctor at once if you have any mood or behavior changes, anxiety, depression, or thoughts about suicide or hurting yourself.