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Some people are experiencing phantom scents after recovering from COVID-19: Otolaryngologist discusses retraining the nose

A growing number of people who have recovered from COVID-19 are flocking to Facebook support groups to try to understand why their breakfast tastes like cigarettes or their favorite latte smells like tar. They describe struggling daily with tasks such as showering and doing laundry due to distorted smell. This phenomena known as parosmia is a rare complication that can occur in the late period after COVID-19 – characterized by a misperception of existing odors.

Much of the published research on parosmia is pre-pandemic with associations to other viral and bacterial infections, neurological disorders and depression. However COVID-19 seems to be uniquely adept at leaving people smelling garbage instead of fresh cut grass or rotten eggs instead of their favorite perfume. 
   
There are a few theories about the mechanisms behind COVID-associated parosmia. One strong contender is that the virus damages specific cells in the nasal cavity that support the smell-detecting neurons which translate odors to the brain. Once the support cells are attacked, the body mounts an inflammation response damaging both the smell detecting neurons and the support cells. In the regeneration process some wires get crossed that distort smell. It is thought that once the neurons are fully repaired – a process that can take weeks to years – a person can recover their sense of smell.

When it comes to data-driven treatments, Peter Manes, MD, otolaryngologist, Yale New Haven Hospital, says “Olfactory retraining has been one of the only treatments where we have some evidence that it improves symptoms. We typically have people start with four scents, using essential oils and ask them to smell each for about 20 seconds, twice daily for three months.” 

Dr. Manes explains that olfactory training can be done with the supervision of an ENT who can track improvement through smell tests, or people can do it on their own. 

“I recommend starting with rose, lemon, eucalyptus and clove before moving on to a new set of scents as these seem to be the best at stimulating smell receptors,” said Dr. Manes.  

Dr. Manes says most people get better within a few weeks. 

“Researchers are looking into supplements and different ways to stimulate the olfactory nerves, but for right now the most important thing for people to do is not give up. Keep working your sense of smell like a muscle.”