Respected Sir, My Daughter Is Of 5years Old Now But

Respected sir,

My daughter is of 5years old now but from the age of 3 years old she got climatic allergy for which she coughs continously and she vomits,we used several kinds of medicines but it is not cured,so doctor suggested for nukast for which her cough stops when we give her nukast,so please suggest us whether it is good her to give continously when she coughs.