Montelukast
"My son has been on this medication since he was four.  He is now 8.  He has been a tough child and I have had some suspicion that something is awry.  After reading some of the responses, I had an ah haw moment.  He has been irritable and having tantrums lately.  It is rare that he is happy.  He nags and whines.  He has no asthma symptoms but I'm not sure if this is due to this medication or he has outgrown it.  I am taking him off this medication and see if I see a change in his disposition."