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What is smell? -

Your nose and an area in the upper throat have special cells that contain olfactory receptor cells. Put simply, when these receptors detect smells, they send a message to the brain. The brain then identifies the specific odor.

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Receptor cells -

Humans possess around 12 million olfactory receptor cells that can detect approximately 10,000 odors.

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How smell works -

There are two ways we detect odors: in the air that we breathe through the front of our nose (orthonasal olfaction) when appreciating the scent of a flower, for example; and through the back of our nose from our mouth, i.e. when chewing food (retronasal olfaction).

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Appreciating smell -

Retronasal olfaction is how we appreciate the flavor of food when it is in our mouth. It's why many people suffering from a smell disorder wrongly believe that there is something amiss with their sense of taste.

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Recognizing danger -

Full olfactory function allows us to sense pleasure or revulsion (depending on what it is detecting). It also acts as a warning system, giving us the ability to detect a gas leak or smoke, for example, or rotten food.

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Psychology and smell -

Smell plays a major role in controlling mood, memory, behavior, and emotion. For example, a smell can act as trigger in recalling a long-forgotten event or experience, whether a happy occasion or a sad one.

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Highly emotive -

Smell is highly emotive. A perfume and fragrance, for example, seeks to convey a wide variety of emotions and feeling. In fact, smell is very important when it comes to attraction between two people.

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Sexual chemistry -

Research suggests that our body odor, our sexual chemistry, produced by the genes that make up our immune system, plays a subtle role in helping us subconsciously choose our partners.

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Are you suffering from a lost or changed sense of smell? -

Loss of smell can be partial (hyposmia) or complete (anosmia). It may be temporary or permanent, depending on the cause. At its most severe, not even the acidic aroma of a lemon, for example, can be detected.

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What are the causes of lost or changed sense of smell? -

Changes in sense of smell are caused by a variety of conditions.

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Common cold -

A stuffy nose from a cold is a common cause for a partial, temporary loss of smell. A blocked or runny nose can impede the function of odor receptors.

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Influenza -

Flu can also be a cause of hyposmia, although the condition affects more than just your nose and throat.

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Sinusitis (sinus infection) -

Sinusitis is a swelling of the sinuses, usually caused by an infection. Besides pain, swelling, and tenderness in your face, symptoms include a blocked nose and a reduced sense of smell.

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Allergies -

An allergy, typically hay fever, can induce sneezing and coughing, itchy, red or watery eyes, a runny or blocked nose, and a loss of smell, among other symptoms.

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Smoking -

Frequent and sustained smoking can cause temporary irritation or congestion inside your nose, leading to a reduced sense of smell.

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Nasal polyps -

A reduced sense of smell or taste is one symptom of nasal polyps—painless soft growths inside your nose that can obstruct airflow. They are not usually serious, but will not clear up unless treated.

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Damage to brain and nerves -

In more extreme cases, loss or changed sense of smell can be the result of damage of the nerves leading to the area of the brain that detects smell caused by head trauma. Brain surgery or a brain tumor can also be the cause.

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Aging -

It's common to lose some of your sense of smell as you get older.

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Link between taste and smell -

The senses of taste and smell are closely linked. The flavors in food, for example, can be tasted because of a combination of your ability to smell and taste.

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Smell or taste disorder? -

A smell disorder may occur for any one of the reasons previously listed. Confusingly, a person with partial (hyposmia) or complete (anosmia) loss of smell may think that they have lost their sense of taste, which isn't necessarily the case. So, what are the reasons for impaired taste?

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Phantom taste perception -

You can experience either a partial or total loss of taste. Interestingly, the most common taste disorder is something called phantom taste perception, or an altered sense of taste. It's characterized by a strong, lingering taste in the mouth, even when it's empty.

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Ageusia -

Ageusia is the loss of taste functions of the tongue, and can result in a person being unable to detect any tastes.

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Dysgeusia -

Dysgeusia is a distortion of the sense of taste. It can cause a persistent taste in the mouth, often metallic or rancid, that can mask other tastes and make all foods taste the same.

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Hypogeusia -

A reduced ability to taste things is known as hypogeusia. A person with this condition may be unable to detect one of the key tastes of sweetness, bitterness, sourness, saltiness, and umami (a pleasant, savory taste).

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Causes of taste disorders -

Causes of taste disorders and loss of taste are similar to those of loss of smell. They include upper respiratory infections, such as the common cold and sinusitis. But taste disorders can also be as a result of middle ear infections, poor oral hygiene, and trauma to ear, nose, and throat.

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Medications -

Some medications may also affect a person’s ability to taste. These include antifungal medications, proton pump inhibitors, and fluoroquinolones, a type of antibiotic.

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Smell disorder treatment -

Smell disorders are not uncommon. They are not usually serious and may get better in a few weeks or months. Treating the cause might help. Steroid nasal sprays or drops, for example, can help if you have sinusitis or nasal polyps.

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Taste disorder treatment -

In simple cases, such as those resulting from the common cold or flu, taste disorder symptoms can be relieved with decongestants or antihistamines. As the infection subsides, your sense of taste will most likely swiftly return.

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Smell training -

Smell training is a supportive technique for people who have suffered smell loss, and in many cases has been proven to help.

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When to see a doctor -

If the disorder persists, book an appointment with a professional health care provider. Your doctor can prescribe an antibiotic to treat more persistent bacterial infections, or remove anything blocking your nasal passage. Similarly, impaired taste can be treated with antibiotics. Medications to minimize the effects of a nervous system disorder or an autoimmune disease that causes the condition may also be prescribed.

See also: Tips for eye health and maintaining good eyesight.

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