Common cold. Artwork of a sagittal section through the human ear, nose and throat to show features of the common cold. The common cold is a viral infection causing fluid discharge (yellow) from inflamed mucous membranes. Inflammation of the mucous membranes of the nose (rhinitis) and the sinuses to the right of the nose (sinusitis) cause runny nose and stuffiness, respectively. Tonsillitis is inflammation of the tonsils (behind the tongue, centre right). Inflammation of the throat below the tonsils (pharyngitis) causes soreness. Middle ear inflammation (otitis media) is shown in the passage at upper right to the right of the cochlea (purple, coiled).