Montelukast

Breathing

Also known as Singulair

Montelukast blocks leukotrienes — chemicals your body releases that tighten airways and drive allergy symptoms. It's a preventer, taken every day to stop trouble before it starts. It will not help during an asthma attack; that's what your rescue inhaler is for. One important thing to know: it carries an FDA boxed warning about mood and behavior changes, so keep an eye on how you feel.

How to take it

When

Once a day, in the evening for asthma. For allergies alone, any consistent time works.

Food

With or without food.

Not for

Sudden breathing trouble. Always keep your rescue inhaler with you — montelukast can't stop an attack that's already started.

Watch your mood

Rarely, it can cause agitation, bad dreams, anxiety, or depression — in adults and children. If your mood shifts after starting it, tell your doctor. This is the medicine's most important warning.

Missed a dose?

Skip it and take the next dose at the usual time. Don't take two in one day.

Common side effects

Headache
Stomach ache
Generally one of the better-tolerated asthma medicines day to day

Call a doctor if

Any new agitation, aggression, depression, sleep disturbance, or thoughts of self-harm — in you or your child — stop and call the doctor
Breathing that's getting worse despite taking it daily
Signs of allergic reaction: rash, swelling, trouble breathing

Educational only. This summary is drawn from public FDA labeling and MedlinePlus and simplified for readability. Your prescription label and your pharmacist always come first — doses and instructions vary from person to person.