Smell, perhaps the least valued of the five senses, plays an important role in the perception not only of smells but also of taste. The loss of smell affects taste, since being able to perceive flavours comes from the olfactory capacity.
Why does loss of smell occur?
The olfactory nerves (the ones that detect odours) are at the top of the nose. When there is an infectious process, the nasal mucosa becomes inflamed and a lot of mucus is produced. This makes it difficult for odours to reach the upper part of the nasal cavity and stimulate the olfactory nerves.
What is the reason for the reduction of smell?
There are several causes that can reduce or even nullify smell, the most frequent being the common cold.
Usually, the sense of smell is recovered at 5–7 days, when the cold is cured. However, unfortunately, in some cases that loss goes on for weeks or even months. One of the most common conditions of prolonged loss of smell is chronic sinusitis with or without nasal polyps.
When the loss of smell is due to sinusitis, either acute (cold that lasts more than 10 days) or chronic, the recovery of the sense of smell and the relief of the rest of the symptoms will be achieved by draining the accumulated mucus.
Other causes of reduction of smell
In recent months, the loss of the sense of smell has been mostly caused by the SARS-CoV-2 coronavirus, which caused the pandemic.
There are other less frequent causes that can produce alterations of smell. They are usually due to damage to the olfactory nerves caused by infections, trauma or tumours.
Loss of the sense of smell is also increasingly recognised as an early symptom of neurodegenerative diseases such as Parkinson’s disease and Alzheimer’s disease.