Tell your doctor right away if you have signs of blood vessel inflammation: flu-like symptoms, severe sinus pain, a skin rash, numbness or a "pins and needles" feeling in your arms or legs.
Stop taking  montelukast and call your doctor right away if you have any unusual changes in mood or behavior (such as agitation, confusion, depression, sleep problems, compulsive behaviors, hallucinations, or suicidal thoughts or actions).
Before taking this medicine
You should not use montelukast if you are allergic to it.
Tell your doctor if you have ever had:
mental illness or psychosis; or
asthma, or a history of severe allergic reaction (sneezing, runny or stuffy nose, wheezing, shortness of breath) after taking aspirin or another NSAID.
The chewable tablet may contain phenylalanine and could be harmful if you have phenylketonuria (PKU).
Tell your doctor if you are pregnant or breastfeeding.
Do not give this medicine to a child without a doctor's advice.
