Blocked nose causes

1. Infections:

Common cold, flu, and sinus infection are mainly caused by viruses.

When bacterial infection occurs, the mucous turns yellow or green.

2. Structural abnormalities (results from an injury or at the time of birth):

Deformities of the nose and nasal septum.

Polyps (fleshy growths) or tumors that occur due to sinusitis.

Enlarged adenoid gland (tonsil-like tissue situated at the back of the nose): One of the     most common causes of nasal congestion.

3. Allergies:

Occur due to the inflammatory response to ALLERGENS, e.g.: house dust and tobacco smoke.

These allergens release HISTAMINE substance, which congestion and excess production of watery nasal mucous.