Smell disorders

How common are smell disorders?
Our sense of smell helps us enjoy life. We delight in the aromas of our favorite foods or the fragrance of flowers. Our sense of smell also is a warning system, alerting us to danger signals such as a gas leak, spoiled food, or a fire. Any loss in our sense of smell can have a negative effect on our quality of life. It also can be a sign of more serious health problems.

How does our sense of smell work?
Our sense of smell—like our sense of taste—is part of our chemosensory system, or the chemical senses.

Specialized sensory cells, called olfactory sensory neurons, are found in a small patch of tissue high inside the nose. These cells connect directly to the brain. Each olfactory neuron expresses one odor receptor. Microscopic molecules released by substances around us—whether it’s coffee brewing or a pine forest—stimulate these receptors. Once the neurons detect the molecules, they send messages to our brain, which identifies the smell. (Because there are more smells in the environment than there are receptors, a given molecule may stimulate a combination of receptors. This response is registered by the brain as a particular smell.)

Smells reach the olfactory sensory neurons by way of two pathways. The first pathway is through your nostrils. The second pathway is through a channel that connects the roof of the throat region to the nose. When we chew our food, aromas are released that access the olfactory sensory neurons through this channel.

If the channel is blocked, such as when our noses are stuffed up from a cold or flu, odors cannot reach the sensory cells and much of our ability to enjoy a food’s flavor is lost. In this way, our senses of smell and taste work closely together. Without the olfactory sensory neurons, familiar flavors such as chocolate or oranges would be hard to distinguish.

What are the smell disorders?
People who experience smell disorders either have a loss in their ability to smell or changes in the way they perceive odors. Hyposmia is a reduced ability to detect odors. Anosmia is the inability to detect odors at all. People who experience changes in how they sense odors may notice that familiar odors are distorted or that something that normally smells pleasant now smells foul. Other people may sense an odor that isn't present at all.

What causes smell disorders?
Smell disorders have many causes, with some more obvious than others. Most people who develop a smell disorder have experienced a recent illness or injury. Common causes of smell disorders are:

Sinus and other upper respiratory infections
Polyps in the nasal cavities
Frontal head injuries
Hormonal disturbances
Dental problems
Exposure to certain chemicals, such as insecticides and solvents
Numerous medications, including some common antibiotics and antihistamines
Radiation associated with the treatment of head and neck cancers

Aging
Other health issues that affect the nervous system, such as Parkinson’s disease or Alzheimer’s disease

How are smell disorders diagnosed?
Both smell and taste disorders are treated by an otolaryngologist, a doctor who specializes in diseases of the ear, nose, throat, head, and neck. Some tests are designed to measure the smallest amount of odor that patients can detect. Another common test consists of a booklet of sheets that contain tiny beads filled with specific odors. Patients are asked to scratch each sheet and identify the odor.

Are smell disorders serious?
Like all of our senses, our sense of smell plays an important part in our lives. The sense of smell often serves as a first warning signal, alerting us to the smoke of a fire, spoiled food, or the odor of a natural gas leak or dangerous fumes.

Problems with our chemical senses may be a sign of other serious health conditions. A smell disorder can be an early sign of Parkinson’s disease, Alzheimer’s disease, or multiple sclerosis. It can also accompany or be a sign of obesity, diabetes, hypertension, and malnutrition. If you are experiencing a smell disorder, talk with your physician.

Can smell disorders be treated?
Many types of smell disorders are curable, and for those that are not, counseling is available to help people adjust to the problem.

Diagnosis by a doctor is important to identify and treat the underlying cause of a potential smell disorder. If your problem is caused by certain medications, talk to your doctor to see if lowering the dosage or changing that medicine may reduce its effect on your sense of smell.
Surgery to remove nasal obstructions such as polyps can restore airflow. Some people recover their ability to smell when the illness causing their olfactory problem is resolved.

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Smell disorders

How common are smell disorders? Our sense of smell helps us enjoy life. We delight in the aromas of our favorite foods or the fragrance of flowers. Our sense of smell also is a warning system, alerting us to danger signals such as a gas leak, spoiled food, or a fire. Any loss in our sense of smell can have a negative effect on our quality of life. It also can be a sign of more serious health problems. How does our sense of smell work? Our sense of smelllike our sense of tasteis part of our chemosensory system, or the chemical senses. Specialized sensory cells, called olfactory sensory neurons, are found in a small patch of tissue high inside the nose. These cells connect directly to the brain. Each olfactory neuron expresses one odor receptor. Microscopic molecules released by substances around uswhether its coffee brewing or a pine foreststimulate these receptors. Once the neurons detect the molecules, they send messages to our brain, which identifies the smell. (Because there are more smells in the environment than there are receptors, a given molecule may stimulate a combination of receptors. This response is registered by the brain as a particular smell.) Smells reach the olfactory sensory neurons by way of two pathways. The first pathway is through your nostrils. The second pathway is through a channel that connects the roof of the throat region to the nose. When we chew our food, aromas are released that access the olfactory sensory neurons through this channel. If the channel is blocked, such as when our noses are stuffed up from a cold or flu, odors cannot reach the sensory cells and much of our ability to enjoy a foods flavor is lost. In this way, our senses of smell and taste work closely together. Without the olfactory sensory neurons, familiar flavors such as chocolate or oranges would be hard to distinguish. What are the smell disorders? People who experience smell disorders either have a loss in their ability to smell or changes in the way they perceive odors. Hyposmia is a reduced ability to detect odors. Anosmia is the inability to detect odors at all. People who experience changes in how they sense odors may notice that familiar odors are distorted or that something that normally smells pleasant now smells foul. Other people may sense an odor that isnt present at all. What causes smell disorders? Smell disorders have many causes, with some more obvious than others. Most people who develop a smell disorder have experienced a recent illness or injury. Common causes of smell disorders are: Sinus and other upper respiratory infections Polyps in the nasal cavities Frontal head injuries Hormonal disturbances Dental problems Exposure to certain chemicals, such as insecticides and solvents Numerous medications, including some common antibiotics and antihistamines Radiation associated with the treatment of head and neck cancers Aging Other health issues that affect the nervous system, such as Parkinsons disease or Alzheimers disease How are smell disorders diagnosed? Both smell and taste disorders are treated by an otolaryngologist, a doctor who specializes in diseases of the ear, nose, throat, head, and neck. Some tests are designed to measure the smallest amount of odor that patients can detect. Another common test consists of a booklet of sheets that contain tiny beads filled with specific odors. Patients are asked to scratch each sheet and identify the odor. Are smell disorders serious? Like all of our senses, our sense of smell plays an important part in our lives. The sense of smell often serves as a first warning signal, alerting us to the smoke of a fire, spoiled food, or the odor of a natural gas leak or dangerous fumes. Problems with our chemical senses may be a sign of other serious health conditions. A smell disorder can be an early sign of Parkinsons disease, Alzheimers disease, or multiple sclerosis. It can also accompany or be a sign of obesity, diabetes, hypertension, and malnutrition. If you are experiencing a smell disorder, talk with your physician. Can smell disorders be treated? Many types of smell disorders are curable, and for those that are not, counseling is available to help people adjust to the problem. Diagnosis by a doctor is important to identify and treat the underlying cause of a potential smell disorder. If your problem is caused by certain medications, talk to your doctor to see if lowering the dosage or changing that medicine may reduce its effect on your sense of smell. Surgery to remove nasal obstructions such as polyps can restore airflow. Some people recover their ability to smell when the illness causing their olfactory problem is resolved. Medline Plus