Any age and either sex.
It most commonly occurs due to a flulike illness damaging the smell nerve fibres within the nose. A variety of conditions including nasal polyps, rhinitis and a distorted nasal septum can mechanically block the passage of odours to the smell receptors in the roof of the nose. Less common smell disorders can result from autoimmune diseases, vitamin and trace element deficiencies and there is even a hereditary condition of smell deficit.
These include reduced or complete loss of smell or distorted smell. Taste is also commonly affected.
Fibreoptic endoscopic examination of the nose can identify the specific causative condition. X-ray scans and blood tests may also be required.
Medical treatment is of the underlying cause and is usually effective.
Surgery to unblock a mechanical obstruction to the passage of odours in the nose may be required.