Hi thanks for contacting HCM... Here you are having allergic infection of nose mucosa and sinuses.... As it is needed to get immediate relief your doctor recommended dexomethasone injection for that... Steroid having antiinflammatory action so useful for it .... Steam inhalation taken two times daily for few days.... Excess spicy and fried food restricted... More water and fruit juice taken.... So steroid can taken to reduce inflammatory swelling but frequent use of it avoided... Alternately inhaled steroid intranasal spray also useful.... Salt water gargles done .... Strepsil like lozenges useful ... Take care