Thank you for your query on Healthcare Magic.
which is an antihistamine and its side effect is weight gain due to increased appetite.
At the same time it will cause drowsiness
leading to sleepiness which may interfere with child intake of food leading to decreased food intake.
Around this age the gain in weight is not so dramatic and nothing to worry if the child is active, healthy, and playful.
Your child weight of 15 kg is corresponding to 25th percentile in CDC growth charts, so it means the weight is in normal range and nothing to worry.
I advise you to stop Practin and you can give one multivitamin
supplement like syrup polybion-L 5ml twice daily for 2 weeks whenever he is having low appetite.
Hope I have answered your query.