http://www.medications.com/effect/view/7766 my 10 year old daughter was put on singulair by an infectious disease doctor that had seen some improvements in kids taking this who have chronic sinus infections and swelling of sinus tissues...my daughter showed an improvement in sinus problems but notice Thu, 21 Feb 2008 10:19:24 -0500 http://www.medications.com/effect/view/7766?item=4996 My 4 year old daughter has been on singulair for about 3 weeks. I am just figuring out that this medication could be the cause of her aggressive behavior, weight gain, nightmares, and cramping. When you posted about the cramping it clicked for me. I'm t http://www.medications.com/effect/view/7766?item=4996