Thanks for your query.
Firstly, the dose of every medicine is dependent on the child's weight. Hence, I cannot comment on the dose prescribed by your son's doctor. But I assume that your doctor is qualified enough to prescribe correct dose.
I will therefore advise you not to exceed the prescribed dose. Had I been your child's treating doctor, I would have considered adding another anti-allergic drug, such as, Montelukast
, in addition to Piriton
Nevertheless, given the fact that your son is allergic to several substances, I would recommend that you consult an Allergic specialist, who knows what would be best for your child.
Dr. Rakesh Karanwal