Odors and Covid-19

Coronavirus or COVID-19 (COronaVIrus Disease 2019) is an acute infectious disease, one of the main symptoms of which is the loss or change of smell: people stop smelling and tasting in the first 2-7 days after infection.

On average, 60% of patients experience a loss of sensitivity to odors or distortion of them (according to PubMed Central from the National Institutes of Health - 47%, according to WHO more than 80%).

In a mild form of the disease, a disorder of smell may be the only sign of the presence of coronavirus. According to a study by Vanderbild University Medical Center, this happens in 25% of cases..

Why does the sense of smell and taste disappear with coronavirus?

Scientists have not yet succeeded in answering this question unequivocally; nevertheless, there are several hypotheses.

Harvard Medical School has suggested that it is all about the protein of the supporting cells that surround the olfactory receptors in the nose (in the olfactory epithelium). It is an ACE2 protein and it is used by the virus to enter the cell, causing it to swell. When there are many swollen supporting cells, they block access to the olfactory receptors. When the swelling subsides, the scent molecules begin to interact with the olfactory receptors again, and the sense of smell gradually returns to normal.

This process differs from what is observed with the flu, which is characterized by a severe runny nose and nasal congestion - they are usually absent with coronavirus (only 4.1% of patients experienced nasal congestion, 2.1% had a runny nose).

On the other hand, there is evidence that the olfactory receptors themselves, as well as the olfactory nerves, olfactory bulb and brain centers, can be affected by coronavirus in severe cases: MRI scans before and after the disease show certain changes in the brain.

Taste can also change with covid, since up to 70-80% of the taste sensation depends on the smell of the food. Accordingly, if a person does not smell odours, then his taste perception of food changes.

On what day does the sense of smell disappear with coronavirus and after how many days does it return?

On average, the sense of smell disappears in the first 3-7 days of the disease, less often in the first 2-3 days.

Typically, the sense of smell returns within 2 weeks, so during one or two weeks patients do not smell anything at all (anosmia) or smell scents in a weak form (hyposmia), perceive them in a distorted form (parosmia) or smell scents that are not there (phantosmia).

In 6-15% of patients, the sense of smell is restored only after a few months. Summarizing the research, we can say that 89% of patients fully restore their ability to smell within 6 months, most of them in the first 2 months.

There have also been recorded cases when the sense of smell did not recover for more than six months or was partially restored.

If the sense of smell has not returned or remains distorted after 2 months, then it is recommended to consult an otolaryngologist.

What is the sense of smell with coronavirus?

According to a study by PubMed Central (National Institutes of Health) in May 2021, perceptual patients experience mostly unpleasant odors (cacosmia). Among them there are the following smells:

Parosmic people have often described odors as “cigarette”, “chemical”, “vinegar”, “ammonia”, “rotten”, “rancid”, as well as the smell of skunk, onions, burnt rubber.

Odor changes with Covid-19

These odor impressions are caused by:

Known triggers are any fried food (especially meat), eggs, onions, garlic, coffee and mint (if you have suspicions of coronavirus, try to sniff mint or coffee: their aroma is often not picked up or recognized by the sick).

How to restore your sense of smell after coronavirus

As a rule, the sense of smell returns to normal after recovery and does not require separate treatment.

If the smell of food is disgusting, then it is recommended to switch to products with a neutral flavor - mashed potatoes, rice, protein shakes.

At home, you can inhale various aromatic oils as training for the olfactory system, as well as do breathing exercises. For other additional measures, including flushing, inhalation and medications (for example, vasoconstrictor and hormonal nasal sprays), you should consult your doctor