Hello and Welcome to ‘Ask A Doctor’ service.
I have reviewed your query and here is my advice.
I would like to make suggestions for your son as follows:
1. Basically for treatment of rash, your son only needs antihistamine.
Chlorpheniramine (Allergex) is an antihistamine.
2. Rinex syrup also contains chlorpheniramine but it also contains
phenylpropanolamine and
phenylephrine in addition, which are useful in cough and
common cold like symptoms. Your son does not need them and they can have some side effects like irritability, etc.
So, I would suggest you to give him Allergex and to apply
calamine lotion as suggested by your doctor. I would not suggest you to give him Rinex for rashes and itching.
Hope I have answered your query. Let me know if I can assist you further.
Regards,
Dr. Parin N. Parmar