What causes you not to be able to smell

Losing your sense of smell can have an unexpectedly big impact on your quality of life. You might not realise how important this sense is until something happens to it. If you’ve noticed changes in your sense of smell then there are many possible reasons. Although the problem will often be temporary and anosmia isn’t usually a sign of anything serious it is important to find out the cause.

What is Anosmia?

If you have lost your sense of smell then you may hear this referred to as anosmia. Anosmia is the medical term used to describe the partial or total loss of the sense of smell. In many cases the loss will only be temporary, but anosmia can be a permanent condition. Anosmia is a symptom rather than a diagnosis and it can have many possible causes. Some of these causes can be serious, but a change in your sense of smell will usually be linked to a minor condition such as a cold or infection.

Possible Causes of Anosmia

Some of the most common causes of anosmia are minor illnesses that have cased temporary blockages in the nose. However, there are some more serious and potentially permanent causes of problems with your sense of smell.

The causes of anosmia can be divided into three main types:

  • Inflammation or irritation in your airways: anything that irritates the delicate tissue lining your airways can affect your sense of smell. Common examples include allergies, sinus infections, colds and the flu, smoking and chronic rhinitis. The cause will often be easy to identify by your other symptoms and the effects are generally temporary.
  • Blockages in your nasal passages: if the flow of air through your nose is obstructed it could affect your sense of smell. The blockage is most likely to be a nasal polyp, which can be removed to clear the airway. However, there is a chance that the growth could be a tumour. Some people also have deformities in their bone or cartilage that affects airflow. Surgery may be able to help with all of these issues.
  • Damage to the nerves or brain: sometimes the problem lies in the system that processes the signals from our nose. Possible causes of this kind of damage include hormonal problems such as an underactive thyroid, certain medications, Multiple Sclerosis, Parkinson’s disease, Alzheimer’s disease, brain tumours, or having had brain surgery. Since many of these conditions can be very serious, it is important to talk to a doctor if you notice a change in your sense of smell. It could be a sign of an underlying problem that needs to be treated.

Our sense of smell can also deteriorate as we get older as a natural part of the ageing process, so if you notice that your sense of smell seems less intense than it used to be when you were younger, this could be completely normal. A small number of people are also born without a sense of smell as a result of a genetic condition.

When to See a Doctor?

It’s normal for your sense of smell and taste to be a bit off when you have a cold, but if it hasn’t returned to normal within a few weeks then you should see a doctor. You may need specialist tests to find out what’s wrong.

Losing your sense of smell won’t usually cause any serious health problems, but it can have a significant impact on your daily life. Without a sense of smell, simple tasks such as checking whether the milk has gone off can become impossible. You can also find it harder to eat a balanced diet if you no longer enjoy the flavours of your food. Some people even find that their mood suffers because they are no longer able to enjoy their meals of the scents of flowers and perfumes.

Since anosmia can have a profound impact on you and there is a small chance that changes in your sense of smell could be linked to something serious, it is a good idea to consult a doctor. Treatments are available that can help with many of the causes of anosmia and it can be important to know why your sense of smell has changed.

The Centers for Disease Control and Prevention lists "new loss of taste or smell" as one of the symptoms of COVID-19.

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  • Information for health professionals

On this page:

  • How common are smell disorders?
  • How does your sense of smell work?
  • What are the smell disorders?
  • What causes smell disorders?
  • How are smell disorders diagnosed and treated?
  • Are smell disorders serious?
  • What research is being done on smell disorders?
  • Where can I find additional information about smell disorders?

How common are smell disorders?

Your sense of smell helps you enjoy life. You may delight in the aromas of your favorite foods or the fragrance of flowers. Your sense of smell is also a warning system, alerting you to danger signals such as a gas leak, spoiled food, or a fire. Any loss in your sense of smell can have a negative effect on your quality of life. It can also be a sign of more serious health problems.

One to two percent of North Americans report problems with their sense of smell. Problems with the sense of smell increase as people get older, and they are more common in men than women. In one study, nearly one-quarter of men ages 60–69 had a smell disorder, while about 11 percent of women in that age range reported a problem.

Many people who have smell disorders also notice problems with their sense of taste. To learn more about your sense of taste, and how it relates to your sense of smell, read the NIDCD's Taste Disorders publication.

How does your sense of smell work?

Your sense of smell—like your sense of taste—is part of your chemosensory system, or the chemical senses.

Your ability to smell comes from specialized sensory cells, called olfactory sensory neurons, which are found in a small patch of tissue high inside the nose. These cells connect directly to the brain. Each olfactory neuron has one odor receptor. Microscopic molecules released by substances around us—whether it’s coffee brewing or pine trees in a forest—stimulate these receptors. Once the neurons detect the molecules, they send messages to your brain, which identifies the smell. There are more smells in the environment than there are receptors, and any given molecule may stimulate a combination of receptors, creating a unique representation in the brain. These representations are registered by the brain as a particular smell.

Smells reach the olfactory sensory neurons through two pathways. The first pathway is through your nostrils. The second pathway is through a channel that connects the roof of the throat to the nose. Chewing food releases aromas that access the olfactory sensory neurons through the second channel. If the channel is blocked, such as when your nose is stuffed up by a cold or flu, odors can’t reach the sensory cells that are stimulated by smells. As a result, you lose much of your ability to enjoy a food’s flavor. In this way, your 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. Without smell, foods tend to taste bland and have little or no flavor. Some people who go to the doctor because they think they’ve lost their sense of taste are surprised to learn that they’ve lost their sense of smell instead.

Your sense of smell is also influenced by something called the common chemical sense. This sense involves thousands of nerve endings, especially on the moist surfaces of the eyes, nose, mouth, and throat. These nerve endings help you sense irritating substances—such as the tear-inducing power of an onion—or the refreshing coolness of menthol.

What are the smell disorders?

People who have a smell disorders either have a decrease in their ability to smell or changes in the way they perceive odors.

  • Hyposmia [high-POSE-mee-ah] is a reduced ability to detect odors.
  • Anosmia [ah-NOSE-mee-ah] is the complete inability to detect odors. In rare cases, someone may be born without a sense of smell, a condition called congenital anosmia.
  • Parosmia [pahr-OZE-mee-ah] is a change in the normal perception of odors, such as when the smell of something familiar is distorted, or when something that normally smells pleasant now smells foul.
  • Phantosmia [fan-TOES-mee-ah] is the sensation of an odor that isn’t there.

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:

  • Aging
  • Sinus and other upper respiratory infections
  • Smoking
  • Growths in the nasal cavities
  • Head injury
  • Hormonal disturbances
  • Dental problems
  • Exposure to certain chemicals, such as insecticides and solvents
  • Numerous medications, including some common antibiotics and antihistamines
  • Radiation for treatment of head and neck cancers
  • Conditions that affect the nervous system, such as Parkinson’s disease or Alzheimer’s disease.

How are smell disorders diagnosed and treated?

Both smell and taste disorders are treated by an otolaryngologist, a doctor who specializes in diseases of the ear, nose, throat, head, and neck (sometimes called an ENT). An accurate assessment of a smell disorder will include, among other things, a physical examination of the ears, nose, and throat; a review of your health history, such as exposure to toxic chemicals or injury; and a smell test supervised by a health care professional.

There are two common ways to test smell. Some tests are designed to measure the smallest amount of odor that someone can detect. Another common test consists of a paper booklet of pages that contain tiny beads filled with specific odors. People are asked to scratch each page and identify the odor. If they can’t smell the odor, or identify it incorrectly, it could indicate a smell disorder or an impaired ability to smell.

Diagnosis by a doctor is important to identify and treat the underlying cause of a potential smell disorder. If your problem is caused by medications, talk to your doctor to see if lowering the dosage or changing the medicine could reduce its effect on your sense of smell. If nasal obstructions such as polyps are restricting the airflow in your nose, you might need surgery to remove them and restore your sense of smell.

Some people recover their ability to smell when they recover from the illness causing their loss of smell. Some people recover their sense of smell spontaneously, for no obvious reason. If your smell disorder can’t be successfully treated, you might want to seek counseling to help you adjust.

Are smell disorders serious?

Like all of your senses, your sense of smell plays an important part in your life. Your sense of smell often serves as a first warning signal, alerting you to the smoke of a fire, spoiled food, or the odor of a natural gas leak or dangerous fumes.

When their smell is impaired, some people change their eating habits. Some may eat too little and lose weight while others may eat too much and gain weight. As food becomes less enjoyable, you might use too much salt to improve the taste. This can be a problem if you have or are at risk for certain medical conditions, such high blood pressure or kidney disease. In severe cases, loss of smell can lead to depression.

Problems with your 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 be related to other medical conditions, such as obesity, diabetes, hypertension, and malnutrition. If you are experiencing a smell disorder, talk with your doctor.

What research is being done on smell disorders?

The NIDCD supports basic and clinical research of smell and taste disorders at its laboratories in Bethesda, Maryland, and at universities and chemosensory research centers across the country. These chemosensory scientists are exploring how to:

  • Promote the regeneration of sensory nerve cells.
  • Understand the effects of the environment (such as gasoline fumes, chemicals, and extremes of humidity and temperature) on smell and taste.
  • Prevent the effects of aging on smell and taste.
  • Develop new diagnostic tests for taste and smell disorders.
  • Understand associations between smell disorders and changes in diet and food preferences in the elderly or among people with chronic illnesses.

Where can I find additional information about smell disorders?

The NIDCD maintains a directory of organizations that provide information on the normal and disordered processes of hearing, balance, taste, smell, voice, speech, and language. To find organizations with information specifically about smell disorders, click on Taste and Smell in the “Browse by Topic” list.

For more information, contact us at:

NIDCD Information Clearinghouse
1 Communication Avenue
Bethesda, MD 20892-3456
Toll-free voice: (800) 241-1044
Toll-free TTY: (800) 241-1055
Email: [email protected]

NIH Pub. No. 14-3231
Updated April 2014

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Last Updated Date:

May 12, 2017

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What causes you not to be able to smell

What causes you not to be able to smell

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News

  • Distinct differences exist between sense of smell distortions associated with COVID-19, Monell Center researchers find

    Monell Center (12/13/2021)
  • NIDCD grantees to develop new smell and taste tests to screen for COVID-19 and possible future viral diseases

    What causes loss of sense of smell?

    A stuffy nose from a cold is a common cause for a partial, temporary loss of smell. A blockage in the nasal passages caused by a polyp or a nasal fracture also is a common cause. Normal aging can cause a loss of smell too, particularly after age 60.

    How do you fix inability to smell?

    Treatments that may help resolve anosmia caused by nasal irritation include:.
    decongestants..
    antihistamines..
    steroid nasal sprays..
    antibiotics, for bacterial infections..
    reducing exposure to nasal irritants and allergens..
    cessation of smoking..

    Can loss of smell be something other than COVID

    It can be due to nasal or sinus inflammation, or other viral infections distinct from COVID-19. And it can even occur as a result of some neurodegenerative diseases like Alzheimer's or dementia or vitamin deficiencies. Rarely tumors can present with smell loss.”

    Is there a disease that makes you unable to smell?

    Anosmia [ah-NOSE-mee-ah] is the complete inability to detect odors. In rare cases, someone may be born without a sense of smell, a condition called congenital anosmia.