thanks for writing to health care magic
it is always better to start any medication particularly in children only after consulting a doctor.
by giving him those two drugs you will be giving two antihistminics together.
does he have any other danger signs.....is he feeding normally
by treating this cold
with antihistaminics you may not prevent his further episode of asthma
........asthma prevention requires preventor therapy and not antihistminics
hope this helps