Singulair Side Effects: Be very wary of this drug! My son was on it for a year and a half http://www.medications.com/effect/view/28689 Be very wary of this drug! My son was on it for a year and a half ...the last six months were a veritable nightmare for him. Severe anxiety issues (had to be hospitalized at one point ) and depression. Doctors kept saying it was not the medication but when YES!!! Same here, my 7 year old son had been on it for nearly 3 Sat, 29 Mar 2008 08:45:24 -0400 http://www.medications.com/effect/view/28689?item=6130 YES!!! Same here, my 7 year old son had been on it for nearly 3 years, this is when we noticed him being hyperactive, aggressive, argumentive, just different! I told his doctor, she did not believe me, she even told me that HER own children are on Singul http://www.medications.com/effect/view/28689?item=6130