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Infectious Diseases

Updated 01 October 2020

Covid-19 can cause a number of smell distortions

There have been reports of Covid-19 patients smelling awful scents that don't exist.

  • Loss of smell from Covid-19 might lead to other olfactory disorders like parosmia and phantosmia
  • These conditions can either distort existing smells or generate smells that don't exist
  • They affect around 8% of coronavirus survivors who lose their sense of smell

The loss of smell is such a widespread symptom of Covid-19 that it has become one of the main ways to diagnose the disease.

But survivors who lost this sense are also reporting other olfactory conditions: parosmia and phantosmia. The former distorts existing smells into an unpleasant, abrasive experience, while the latter conjures up smells that don't exist.

READ | Loss of smell from Covid-19 differs from common cold 

Damage to nerves

These conditions are closely linked to anosmia and tend to be the result of damage to olfactory nerve fibres, in this case, caused by a viral infection. It can also be caused by smoking, cancer, brain trauma and other neurological conditions.

While they don't have an impact on your health, the above conditions can impede quality of life when your favourite foods start smelling like garbage and affect your appetite. The largest study on parosmia found that the biggest triggers were tobacco, coffee, perfumes, chocolate and gasoline.

READ MORE | Covid-19 and loss of smell: Harvard researchers uncover why it happens 

The numbers

According to a study on Covid-19's impact on the senses, other chemosensory distortions are understudied in reports on loss of taste and smell. Fortunately, cases of parosmia and phantosmia still appear to be rare: about 7.5% of the study's respondents reported parosmia, with around 8.3% reporting phantosmia.

These disorders also present much later after recovery – sometimes months later. The study focused on people recently recovered, which means there has not been enough time to investigate the true prevalence of these smell distortions.

The Smithsonian Magazine also reported that there's been a steady increase of online support groups during the pandemic for people struggling with parosmia and phantosmia, alongside anosmia. 

READ | How common is losing taste and smell among Covid-19 patients? Scientists took a closer look 

Recovery

People, however, tend to recover from parosmia and phantosmia quite quickly as the damaged nerves repair themselves. One study found that more than half of the participants tended to improve or completely recover their smell and taste after about a month.

Unfortunately, full sense recovery after an infection can take on average between two and three years, and there are few treatment options, with surgery only rarely an option.

According to Healthline, zinc, vitamin A and antibiotics are also sometimes prescribed to treat these smell disorders.

Research

More research is being conducted on the impact of Covid-19 on the olfactory senses, including by the Global Consortium for Chemosensory Research that aims to find a definitive link between respiratory illnesses like Covid-19 and their effect on smell and taste. 

You can also participate in their global studies if you suffer from these olfactory disorders.

READ MORE | Loss of smell and taste might be long-term for some Covid-19 survivors

Image credit: Pixabay