Yes Vitamin C does improve your immunity. However seasonal allergies require some anti-histamines or steroids. Oral steroids cannot be given for long duration. Therefore intra nasal steroidal sprays which contain micrometered doses are the best treatment to keep allergy symptoms at bay. They act locally and have minimal to no systemic side effects. Recognise the seasons when your allergies flare up. Start Flomist/Austril Nasal spray( Fluticasone Ft) 2puffs twice a day for 15 days then taper the dose to once a day for next 7 days and use it Sos. Remember to take the spray with your head leaning forward. Doing regular Breathing exercises and pranayam also keep your allergic nasal symptoms under control. Your allergies may also subside if you move to a new place since the spectrum of allergens vary every 100 aerial metres.

If you are in agra meet me personally in my opd or you can do online consultation for prescription and counseling for the same