Common condition in which displacement of the septum causes unequal width of the two inner parts of the nose. It is in fact rare for them to be equal in width, and the condition usually causes no complications, even if the deviation is large, although it can lead to slight breathing difficulties and inadequate warming and moistening of the air. Also bacteria and other foreign bodies are not properly filtered out of inhaled air. Deviated septum can be caused in two ways. The nasal septum develops in the embryo from a piece of cartilage and a piece of bone, and thickening of the bone and projection can occur at the joint. The deviation can also result from damage (such as a blow) to the nose. The condition can cause nasal blockage; most people are aware that they can breathe better through one nostril than the other. A dry throat can also result, because air passing through the nose is insufficiently moistened; sinusitis also occurs more frequently because the nose is not so effective in removing pollen and viruses from the air, causing headache or a congested feeling in the head. The patient usually suffers discomfort from a combination of deviated septum and some other factor that impairs breathing, e.g: swollen mucous membranes if the patient has a cold. When the membrane returns to normal, discomfort will be reduced or disappear. Diagnosis is simply effected by examination though the nostrils by the family doctor or an ENT specialist. Treatment of the swollen mucous membrane is usually adequate, by inhaling salt water or using a nasal spray. The deviated septum itself can be treated only by surgery, either to reset the septum or to remove thickened bone. The operation can be conducted under local or general anaesthetic. If there is little discomfort a deviated septum need not be treated.