Singulair (montelukast) pediatric side effects?

Usually none: The list of possible side effects for singulair (montelukast) is long, but most are the same symptoms kids get all the time from common illnesses, meaning kids got sick while testing the medication: headache, flu-like symptoms, stomach ache, cough, dizziness, fatigue, decreased appetite, rash, fever, itching, hives, ear infections, colds, anxiety, restlessness, tremor, sleep issues. Rarely, serious ones happen.

Behavioral problems: Have seen some patients having severe behavioral disorders, sometimes aggression, hyperactivity.

Almost none: It is a pretty safe drug. There was some unproven concern about depression in adolescents.