Singulair Side Effects: May 16 y.o. daughter has chronic sinus infections and sever heada http://www.medications.com/effect/view/38265 May 16 y.o. daughter has chronic sinus infections and sever headaches. They said it was allergies and put her in Allegra D and Singulair. Headaches seemed better with slightly fewer sinus infections. Once I heard about the mood swings and Singulair I too Alopecia (hair loss) was reported as an adverse reaction to Singu Thu, 22 Jan 2009 16:09:43 -0500 http://www.medications.com/effect/view/38265?item=16289 Alopecia (hair loss) was reported as an adverse reaction to Singulair in the United Kingdom Medicines and Healthcare Products Regulatory Agency adverse event reporting system: follow this link for a list of reactions from Jan 1997 - Nov 2008 and run a s http://www.medications.com/effect/view/38265?item=16289