Hello. Thank you for asking at HCM. Montelukast is useful in both allergic rhinitis and asthma and Levocetirizine is useful in allergic rhinitis (nose symptoms) mainly. As your son has no complaints and has improved a lot, I would suggest you to drop levocetirizine first and continue montelukast only for 14 days. Decision regarding tapering montelukast depends upon how severe your son s bronchitis or asthma is. If he has only occasional episodes of bronchitis, he can stop montelukast and restart again when he develops symptoms of nose allergy or bronchitis and continue till the symptoms subside. If he has seasonal problems, I would suggest him to start montelukast 2 weeks prior to expected bad season and continue throughout the season. However, if he has frequent bronchitis all throughout the year, I would suggest him to continue montelukast daily at least for a year to prevent attacks of allergic bronchitis. I would also suggest you to consult an Allergist-Immunologist who will advise him allergy testing. This will help him to identify the substances he should avoid. An Allergist may advise him allergen immunotherapy which modifies his immunesystem to reduce allergy symptoms. I would suggest your son regular breathing exercises, a healthy nutritious diet & avoidance of dusts-smoke-air pollution as much as possible which will help him in a long run. Hope this will be helpful to you. Wish your son the best of the health. Regards.