My 2 year old is diagnosed with asthma, he is currently on montelukast 4 mg , is asthama curable? and what is the cause of astham in so young children?

Some thoughts: I am reluctant to use the asthma label for any kid under 5 because there are so many things that can cause recurrent wheezing in toddlers that disappears by school age. True asthma has genetic and lifelong implications & can vary in intensity from year to year & within an affected family. If he does have family with asthma it may be true. Many viral illnesses trigger asthma like wheezing.