Smell Disorders

The sense of smell adds a quality of life that is difficult to explain.

Smell is present in every day of our lives; From the pleasure we get from the smell of a perfume to the satisfaction of the smell of the coffee we drink next to the toast we eat or to a burning smell that warns us. The quality and intensity of this sense of smell varies according to the anatomical structure of the superficial covering (mucosa) that covers the nose, and the condition of the peripheral and central nervous system.

In order for us to smell, the odor molecules must reach the olfactory mucosa, which is located at the ceiling of the nasal cavity. This requires an airflow. This current is sometimes by breathing through our nose and sometimes by the smell molecules carried by the air flow up the back of the throat and the nasal region while eating, which is related to the flavor we get from the food we eat. The odor molecules that reach the olfactory mucosa interact with the receptors there, and the sense of smell is transmitted to the relevant part of the brain through a series of electrical activities.


The conditions listed below may cause olfactory disorders.

  • Occlusive diseases of the nose and sinuses

  • upper respiratory tract infections

  • head injuries

  • Aging

  • Congenital (congenital)

  • Toxic chemical exposure

  • tumors

  • HIV infected patients

  • Epilepsy

  • psychiatric diseases

  • Medicines

  • surgical interventions

  • unknown causes

Polyps (grape cluster-like fleshy structures) that cause complete obstruction in the nose, and severe swelling in the inner lining of the nose may cause the inability to smell. Bone and cartilage curvature originating from the middle part of the nose may cause a decrease in smell by preventing airflow. Adhesions and scar tissue formed between the middle part of the nose and the meat structures (concha) on the side wall due to previous intranasal surgery are another cause of olfactory dysfunction.

Sense of smell after upper respiratory tract infection

Loss of sense of smell after upper respiratory tract infection is common. This is usually due to congestion caused by discharge and swelling. It often returns to normal within 1-3 days. In very few, the sense of smell does not return. The patients in this group are between the ages of 40-70 and most of them are women. One third of patients with upper respiratory tract infection and loss of smell recover with or without treatment. In two-thirds of the patients, various degrees of improvement can be observed over the years.

Loss of sense of smell occurs in 5-10% of patients with minor or major head trauma. The rate of loss of sense of smell varies depending on the extent of the trauma. However, there may be complete loss of sense of smell in minor traumas. Depending on the part affected by head trauma, the degree of loss of sense of smell may vary. Loss of smell usually occurs immediately after trauma, but sometimes patients can notice it months later. Less than 10% of the loss of sense of smell due to head trauma recovers. The mechanism of olfactory loss due to head trauma has not been fully elucidated. There are multiple theories about this.

sense of smell in aging

Aging is another cause of decreased sense of smell. In the fifties and sixties, the sense of smell declines sharply. This decrease is greater in women. Decreased sense of smell is sometimes the earliest finding in Alzheimer’s and Parkinson’s diseases.

Children realize their congenital (congenital) loss of smell after about 8 years of age. In this group of patients, sharp, offensive odors can be distinguished and the sense of taste is intact. In most of them, there is a loss of sense of smell against certain groups of chemicals or chemicals. Congenital olfactory disorder can also be part of some genetic diseases.

Loss of sense of smell due to exposure to toxic chemicals can occur within days. Or it occurs due to years of exposure. Long-term smoking can also cause a loss of sense of smell. This loss of sense of smell can be temporary or permanent. Due to the exposure time and the intensity of exposure, necessary precautions should be taken and warnings should be made in terms of loss of sense of smell for employees in workplaces where such chemicals are present.

Tumors in the nose or brain can cause loss of sense of smell. If there is nasal congestion, loss of sense of smell, nosebleeds, visual disturbances or symptoms related to the central nervous system, this group of tumors should be investigated.

Defects in tests related to smell have been detected in HIV-infected people.

In some cases of epilepsy, auras related to smell can be seen (1-30%). This aura usually lasts for a few minutes.

In psychiatric diseases such as depression and schizophrenia, complaints about the sense of smell can also be seen.

Many drugs cause changes in the sense of smell. When this group of drugs is stopped, the complaints usually go away, sometimes they can be permanent.

Loss of sense of smell may occur after some surgeries performed inside the nose.

Despite all the examinations, the reason for the loss of sense of smell in some patients may not be found.

For diagnosis in olfactory disorders:

The patient’s history should be questioned in detail. It is important how long and how severe the complaint is. Recent head trauma, history of upper respiratory tract infection should be questioned. The drugs used, under-functioning of the thyroid gland, metabolic diseases are questioned. In the physical examination, nose, mouth and neurological examination are performed. Nasal endoscopy is helpful if necessary. Tomography is performed in terms of diseases related to the nose and sinuses.


In the treatment, if there are intranasal problems that prevent airflow, these are solved first. Care should be taken to protect the olfactory epithelium (superficial covering of the olfactory region on the ceiling of the nasal cavity) while these are being operated. Intranasal steroids, antibiotics, allergy treatment are arranged according to the cause. There is no effective treatment method for congenital and trauma-related smell disorders. Vitamin A, B and oral zinc have been used in treatments, but the results are not satisfactory. Some olfactory disorders resolve spontaneously. Fire and smoke detectors at home can be used as a precaution against fire and gas poisoning in people who have a smell disorder and do not improve.

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