If the lining in the nose has been irritated for a long time then it can swell so much that it begins to swell into the nasal cavity. This is what nasal polyps are – swollen nasal lining. Most nasal polyps respond well to treatment of the inflammation using steroids; either inside the nose in the form of drops or a spray or sometimes using oral steroid tablets. Occasionally the nasal polyps continue to cause blockage of the airway and/or sinuses (see sinusitis) with the nasal drip (see nasal drip) despite the medication; surgery can be offered to remove the polyps and open up the nasal sinuses. A CT scan of the sinuses is often used to assess the severity of the polyps and how many of the nasal sinuses are involved. The scan will be discussed with you together with the details of endoscopic sinus surgery and the risks involved (see FESS).