http://www.medications.com/effect/view/37807 My son who is 5 years old was on Singulair for 5months. He turned into a total different child. He developed extreme OCD, anxiety, excessive crying, scared at night, and irritability. After researching I found out it was the Singulair causing his symptoms Wed, 07 Jan 2009 17:32:14 -0500 http://www.medications.com/effect/view/37807?item=15801 I did contact the FDA about perm damage from this drug,they said if they get enough reports they will investigate it.So my suggestion to you is to report it just as you wrote it here.My son has been off now for 10 mnths and although 90% better 10% still ne http://www.medications.com/effect/view/37807?item=15801