This is a prescription medicine. Only take it if it has been prescribed for you after a medical assessment, and follow your doctor’s and pharmacist’s instructions.
Montelukast (Singulair) is a once-daily tablet that blocks leukotrienes, chemicals that narrow airways and trigger allergy symptoms. It’s used to prevent asthma symptoms and exercise-induced bronchospasm, and sometimes for allergies.
Not a rescue medicine
Montelukast won’t relieve a sudden asthma attack. Always carry your rescue inhaler.
Side effects
- Headache
- Stomach upset
- Upper respiratory infections
FDA boxed warning: mood and behavior
Montelukast can cause serious neuropsychiatric effects in some people, including agitation, nightmares, sleep problems, depression and suicidal thoughts. Because of this, it isn’t a first-choice treatment for mild allergies. Stop and contact your doctor right away if you or your child notice these changes. Seek emergency help if there is an immediate risk of harm.
Frequently asked questions
When should montelukast be taken?
Usually in the evening for asthma; for exercise-induced symptoms, at least 2 hours before exercise if not already taking it daily.
General information only. It isn’t a substitute for advice from your doctor or pharmacist.
Source and further reading
MedlinePlus patient medicine information. This overview does not list every warning or interaction; read the leaflet supplied with your medicine.
