ear, nose, and throat disorders
Loss of Smell
Causes of Anosmia
Anosmia that is not the result of aging occurs when swelling or another blockage of the nasal passages prevents odors from reaching the olfactory area or when parts of the olfactory area or its connections to the brain are destroyed (see table). The olfactory area, where odors are detected, is located high in the nose (see). The most common causes include (young adults) Viral infections Alzheimer Disease (older adults) A common cause of permanent loss of smell is a head injury, as may occur in a car accident. Head injury can damage or destroy fibers of the olfactory nerves (the pair of cranial nerves that connect smell receptors to the brain) where they pass through the roof of the nasal cavity. Sometimes the injury involves a fracture of the bone (cribriform plate) that separates the brain from the nasal cavity. Damage to the olfactory nerves can also result from infections (such as abscesses) or tumors near the cribriform plate. Another common cause is an upper respiratory infection, especially Influenza (Flu) (flu). Flu may be the cause in up to one quarter of people with hyposmia or anosmia. Medications can contribute to anosmia in susceptible people. Polyps, tumors, other infections in the nose, and seasonal allergies ( Allergic Rhinitis ) may interfere with the ability to smell. Occasionally, serious infections of the nasal sinuses or radiation therapy for cancer causes a loss of smell or taste that lasts for months or even becomes permanent. These conditions can damage or destroy smell receptors. The role of tobacco is uncertain. A very few people are born without a sense of smell. Anosmia or hyposmia may be an early symptom of COVID-19 , an acute respiratory illness that can be severe. COVID-19 is caused by the coronavirus called SARS-CoV2. 