Thank you for your query.
About 18% of patients complain of headache following the use of Montelukast
which is similar to that of a placebo. Levocetrizine will not fully control the allergic reactions and your daughter may have the reactions occasionally. It is advisable that she starts Montelukast and continue it for a while. In due course of time she will be able to overcome the headache problem and be free from the allergic reaction.
At the same time try to identify the substance which precipitates the allergic reaction so that it can be avoided. You shall have to work in close coordination with the pediatrician
to identify it.
I hope I have answered your query to your satisfaction.