Hello Since you are having cough from 2 years. Steam inhalation provide some relief . Fexofenadine ( allegra ) levolin ( levosalmaetrole ) somewhat working but not providing complete relief. Your question is that is it post nasal discharge . Post nasal discharge is caused by allergy due to some allergens like , dust , mites , pests ( cockroaches ) , pollen , molds , sudden increase or decrease in temperature , fine dusting powder . These allergen causes bronchoconstriction , hence there develop bronchospasm . This bronchoconstriction causes cough and breathlessness ( and also post nasal discharge ) . As all these symptoms are precursor of ASTHMA ( ALLERGIC ASTHMATIC BRONCHITIS ) . So avoidance will provide great relief . When such type of patient visit my clinic ( this is very common now a day ) I prescribe them to take monteleukast+ bambuterol tablet once or twice in day according to severity of symptoms and disease. Also take cough syrup ( dextromethophan+ chlorpheniramine maleate + ambroxol i.e eases mucus ). Steam inhalation also causes bronchodilation , that s why there is relief . Hot coffee also provide relief. Hope this information will be helpful for you.