The surgery, septoplasty and turbinectomy, are used to treat nasal airway obstruction. Medicines like cetirizine are used to treat nasal allergies. So if one has both, the surgery itself will not make the allergies go away. Therefore, medicines like cetirizine may be needed indefinitely if symptoms are bad enough. Cetirizine is generally very well tolerated. You can look online for the list of possible side effects.
your suggestions/ detailed clarifications helped us a lot. also appreciate your prompt response. thank you very much.