Your sense of smell serves more than one purpose. It not only allows you to enjoy a variety of aromas, but also warns you of potential dangers such as smoke or leaking gas.
Loss of smell can be partial (hyposmia) or complete (anosmia), and may be temporary or permanent, depending on the cause. Although loss of smell is rarely a symptom of a serious condition, even a partial loss of smell could cause you to lose interest in eating, which could possibly lead to weight loss, malnutrition or even depression.
The common cold with nasal congestion is the most common cause for a partial, temporary loss of smell. Obstruction in the nasal passages, particularly from polyps or nasal fractures, also is common. Normal aging also may cause a loss of smell, which may be progressive, becoming complete and permanent.
Smell results when individual molecules, suspended in the air, are inhaled and attach to receptors in the mucous membranes of the nose, stimulating nerves that connect directly to the brain. Any problem within this olfactory system — congestion or obstruction in the nose, inflammation of its lining, nerve damage, or altered brain function — affects your ability to smell normally.
While total loss of smell is fairly rare, and the more common causes improve with time, symptoms are sometimes severe enough to result in significant problems or distress. An intact sense of smell is necessary to accurately taste and enjoy food; losing this sense could cause you to lose interest in eating, potentially leading to weight loss, malnutrition or even depression.
Conditions that cause temporary irritation or congestion of the mucous membranes lining the inside of your nose are the most common cause of loss of smell. These may include:
Conditions or obstructions that block the flow of air through your nose can include:
Less commonly, the nerves leading to the olfactory center of the brain or to the brain itself can be damaged or deteriorate due to:
Loss of smell caused by colds, allergies or sinus infections usually clears up on its own after a few days. If this doesn't happen, consult your doctor so that he or she can rule out more-serious conditions.
Loss of smell can sometimes be treated, depending on the cause. Your doctor can give you an antibiotic to treat a bacterial infection, or remove obstructions that are blocking your nasal passage.
In other cases, loss of smell can be permanent. After age 60, in particular, you're at greater risk of losing your sense of smell.