The cause of nasal polyps is not well understood, some believe that it result from allergy while others believe that it is caused by the sinus infection. Polyps block the nose. Large polyps create obstruction in the nasal breathing, forcing the individual to breath through mouth. Polyps also caused due to reduced sense of smell, rhinitis, swelling and inflammation of the lining of the nose. Polyps look like small grapes and can appear singly or in clusters in the nasal cavity. These polyps cause nasal blockage, runny nose, sneezing, poor sense of smell, taste, catarrh, headache, congestion in the fore-head and very occasionally bloody discharge from the nose.