Smell is one of the most important sensory organs for the daily life of human beings, however, it can suffer alterations such as loss of smell , which affects the quality of life of many people.

In this context, we present the following article where we provide you with important information about what causes loss of smell and how you can recover it.

What is loss of smell?

Loss of smell, also called anosmia , is a condition where the sense of smell suffers from a sensitivity dysfunction in the perception of odors. (1)

In this sense, patients suffering from anosmia lose olfactory perception in its entirety , however, there is another condition called hyposmia (2) where the patient partially loses olfactory sensitivity.

Note: Anosmia can equally affect subjects, regardless of their race or sex , however, as the person advances in age, the probability of suffering from this pathology increases.

What are the causes of loss of smell?

Below, we mention the most common causes, to which the loss of smell is attributed:

1. Abnormalities and obstruction in the nasal structure

The causes attributed to the loss of smell due to abnormalities in the nasal structure are due to situations such as the destruction of the olfactory neuroepithelium or destruction of the central pathways.

To highlight: Other causes such as obstruction in the nasal passages, can give rise to anosmia such as bilateral sinonasal polyposis. On the other hand, some scientific studies describe the relationship of olfactory bulb atrophy with anosmia. (3)

Also, other nasal complications can cause loss of smell such as acute rhinitis, chronic rhinitis, Killian’s solitary polyp, which obstruct the entire nasopharynx. (4)

2. Infections and allergies

Infections in the upper respiratory tract are other very common causes of loss of smell in humans. Illnesses such as sinusitis , flu and colds , commonly among their symptoms is anosmia .

Likewise , allergic reactions that affect the olfactory function can cause a temporary loss of the sense of smell such as allergic rhinitis.

You should know: Studies indicate that anosmia together with the loss of the ability to taste , in the absence of other pathologies, are key symptoms in patients with Covid 19 (coronavirus) in the context of the pandemic. (5)

3. Head injuries

Sometimes, the loss of smell can be a sign of an underlying disorder or disease in the central nervous system , such as sequelae of head injuries, when the damage suffered affects those areas of the brain related to the perception and identification of smells and tastes.

Note: A study describes that among the causes of anosmia, head trauma is found. (6)

4. Endocrine and neurological problems

Many patients with diseases such as Cushing’s syndrome, hypothyroidism , pseudohypoparathyroidism, and adrenocortical insufficiency, which affect the endocrine system, have been linked to loss of smell.

Other diseases caused by degenerative causes of the central nervous system, such as Alzheimer’s disease and Parkinson’s disease, have also been linked to loss of olfactory ability.

To highlight: Some scientific studies describe the association between Alzheimer’s disease and anosmia. (7)

5. Drugs 

Another cause that can affect the altered sense of smell is the prolonged use of certain medications, which can cause loss of smell as side effects.

In this case may include antihypertensives, statins, anesthetics and prolonged use of nasal decongestants, among other medications. (8)

How to recover the sense of smell?

To treat loss of smell problems, there are several therapeutic strategies which we mention below:

1. Medications and corrective surgery

Pharmacological strategies aimed at correcting anosmia, for those causes attributed to infections, are used with medical indication. Here, the doctor can use antihistamines and, if necessary, intranasal corticosteroids and antibiotics.

In cases of anosmia due to obstruction, either due to polyps or a deviation of the nasal septum, surgical intervention will be necessary , as well as in those cases of chronic sinusitis.

You should know: There are therapies called olfactory training, aimed at olfactory recovery after post-viral anosmia. (9)

2. Apply home security measures

Other recommended particularities during the suffering and recovery from anosmia, is to follow some safety recommendations to avoid accidents in the house, such as the use of smoke detectors to prevent fires, care in the consumption of stored food and the domestic gas use.

3. Add flavorings to foods to stimulate taste

Likewise, the aid that must be used during the recovery of the olfactory capacity in case the loss is partial, is the use of flavorings in meals to improve satisfaction in food. 

This is due to the fact that both smell and taste use chemoreceptor mechanisms, which are complementary to have a pleasant sensation in food.

4. Avoid Excessive Use of Decongestants 

Likewise, the use of nasal decongestants to reduce inflammation and mucus in the nose should be avoided in an uncontrolled way , since these drugs can impair the mechanism of perception and interpretation of odors of the olfactory system.

Key Findings

  • Anosmia is the complete loss of the ability to smell in humans.
  • Loss of smell usually occurs more frequently in the elderly.
  • Loss of smell can be caused by infectious diseases of the upper respiratory tract or trauma to the brain.
  • Loss of smell, or anosmia, can be present in diseases such as Alzheimer’s or Parkinson’s.

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