Hello. Thank you for asking at HCM. I went through your history and would like to make suggestions for you as follows: 1. First of all, to address your main query, in my opinion, montelukast (myteka) is usually considered safe for long term use, even for years together. Common side effects are headache, nausea, stomach upset, etc. If you are not experiencing it, you can continue taking it. 2. Were I treating you, I would suggest you allergy testing which will help you identify the substances causing allergies to you and also to know the measures to avoid them. As you get more symptoms at night, I would think of allergy to house dust mites and indoor molds first. Based on allergy testing report, an Allergist-Immunologist may prescribe you allergen specific immunotherapy which works on immune system to improve allergy symptoms gradually over a long period. 3. I would also suggest you regular breathing exercises and a healthy diet which will improve your lung capacity and immunity respectively. 4. In general, I would suggest you to avoid exposure to dusts, smokes and air pollution as much as possible. Hope above suggestions will be helpful to you. Should you have any further query, please feel free to ask at HCM. Wish you the best of the health. Thank you & Regards.