@ldan Hello, Montelukast is used to prevent the symptoms of asthma. It's usually prescribed when asthma is mild and can stop it from getting worse. It can also help people with asthma who have breathing difficulties when they exercise (exercise-induced asthma) and seasonal allergies, such as sneezing, itchiness, and a blocked or runny nose. You should avoid taking medicine for this long. Talk to your doctor or get medical care right away. Thanks!