Acquired anosmia develops later in life due to various causes, such as upper respiratory infections, head trauma, or neurodegenerative diseases.

[4] In contrast, congenital anosmia is present from birth and is typically caused by genetic factors or developmental abnormalities of the olfactory system.

[8][9] When anosmia is caused by inflammatory changes in the nasal passageways, it is treated simply by reducing inflammation.

[17] People with sudden onset anosmia may find food less appetizing, though congenital anosmics rarely complain about this, and none report a loss in weight.

Loss of smell can also be dangerous because it hinders the detection of gas leaks, fire, and spoiled food.

Misconceptions of anosmia as trivial can make it more difficult for a patient to receive the same types of medical aid as someone who has lost other senses, such as hearing or sight.

[citation needed] Many experience one sided loss of smell, often as a result of minor head trauma.

The lack of the sense of smell at birth, usually due to genetic factors, is referred to as congenital anosmia.

To avoid such damage and the subsequent risk of loss of smell, vasoconstricting nasal sprays should be used only when absolutely necessary and then for only a short amount of time.

Loss of smell has also been found to be more predictive of COVID-19 than all other symptoms, including fever, cough, or fatigue, based on a survey of 2 million participants in the UK and US.

[29][30] Many countries list anosmia as an official COVID-19 symptom, and some have developed "smell tests" as potential screening tools.

A prednisone regimen is adjusted based on the degree of the thickness of mucosa, the discharge of oedema and the presence or absence of nasal polyps.

[59] Although very early in development, gene therapy has restored a sense of smell in mice with congenital anosmia when caused by ciliopathy.

In this case, a genetic condition had affected cilia in their bodies which normally enabled them to detect air-borne chemicals, and an adenovirus was used to implant a working version of the IFT88 gene into defective cells in the nose, which restored the cilia and allowed a sense of smell.