When i get cold it takes months to get ride of the blocked nose. what could be the reason?

Allergies?: Prolonged nasal stuffines is often a sign of environmental allergies. Talk to your doctor about a trial of an antihistamine or a prescription nasal spray. Meanwhile, you might try using a saline nasal spray at bedtime.

Sinusitis: A cold that does not go away after 7-10 days is most likely a sinus infection. If these symptoms have persisted for months, i would think this might be chronic sinusitis. Allergies can be considered as well.