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Loss of smell anosmia (an-OZ-me-uh) can be partial or complete, although a complete loss of smell is fairly rare. Loss of smell can also be temporary or permanent, depending on the cause.
Loss of smell is rarely a symptom of a serious condition. Still, an intact sense of smell is necessary to fully taste and enjoy food. Loss of smell could cause you to lose interest in eating, which could possibly lead to weight loss, malnutrition or even depression.
Nasal congestion from a cold, allergy, sinus infection, or poor air quality is the most common cause of anosmia. Other anosmia causes include:
- Nasal polyps small noncancerous growths in the nose and sinuses that block the nasal passage.
- Injury to the nose and smell nerves from surgery or head trauma.
- Exposure to toxic chemicals, such as pesticides or solvents.
- Certain medications, including antibiotics, antidepressants, anti-inflammatory medication, heart medications, and others.
- Cocaine abuse.
- Old age. Like vision and hearing, your sense of smell can become weaker as you age. In fact, one’s sense of smell is most keen between the ages of 30 and 60 and begins to decline after age 60.
- Certain medical conditions, such as Alzheimer’s disease, Parkinson’s disease, multiple sclerosis, nutritional deficiencies, congenital conditions, and hormonal disturbances.
- Radiation treatment of head and neck cancers.
Factors that disrupt the sense of smell
Anosmia means loss of the sense of smell, while hyposmia means reduced smell sensitivity. Measuring the degree of ‘smell loss’ is difficult, since the experience of smell is subjective. Unlike other senses, there is no diagnostic test that can judge smell sensitivity with objective accuracy. However, different factors that are known to interfere with the smell sense include:
- Chemicals – a wide range of industrial chemicals, including heavy metals, inorganic and organic compounds, acids and pollutants.
- Diseases of the hormonal system – such as diabetes, Cushing’s syndrome and hypothyroidism.
- Diseases of the nervous system – such as Alzheimer’s disease, multiple sclerosis, migraine, Korsakoff syndrome, brain tumours, brain lesions and epilepsy.
- Drugs – stimulants (such as amphetamines and cocaine), depressants (such as morphine), some antibiotics and other drugs, including the vasoconstrictors in nasal sprays.
- General diseases – such as bronchial asthma, leprosy and cystic fibrosis.
- Trauma – including blows to the head or injuries to the nose.
If you experience a loss of smell that you can’t attribute to a cold or allergy or which doesn’t get better after a week or two, tell your doctor. Your doctor can take a look inside your nose with a special instrument to see if a polyp or growth is impairing your ability to smell or if an infection is present.
Further testing by a doctor who specializes in nose and sinus problems an ear, nose, and throat doctor (ENT, or an otolaryngologist) may be needed to determine the cause of anosmia. A CT scan may be necessary so that the doctor can get a better look of the area.
Everyday factors which diminish the sense of smell
The sense of smell can be dampened by everyday factors, including:
- Smoking – particularly for the half hour after smoking a cigarette.
- Nasal mucus – caused by a number of ailments, such as colds, influenza, hay fever or sinusitis.
- Adaptation – experienced when the olfactory cells are flooded to saturation point with particular odour molecules.
If nasal congestion from a cold or allergy is the cause of anosmia, treatment is usually not needed, and the problem will get better on its own. Short-term use of over-the-counter decongestants may open up your nasal passages so that you can breathe easier. However, if the congestion gets worse or does not go away after a few days, see your doctor. You may have an infection and need antibiotics, or another medical condition may be to blame.
If a polyp or growth is present, surgery may be needed to remove the obstruction and regain your sense of smell.
If you suspect a medication is affecting your sense of smell, talk to your doctor and see if there are other treatment options available that won’t affect your ability to smell. However, never stop taking a medication without first talking with your doctor.
Sometimes a person will regain his or her sense of smell spontaneously. Unfortunately, anosmia is not always treatable, especially if age is the cause. But there are steps you can take to make living with the inability to smell more pleasant and safer. For example, put fire detectors and smoke alarms in your home and office and take extra care with leftovers. If you have any doubt about a food’s safety, don’t eat it.
If you smoke, quit. Smoking can dull your senses, including your sense of smell.