COVID-19 and Loss of Taste and Smell

One of COVID-19's many mysteries is the phenomenon of loss of taste and smell. After many months of study, medical professionals are chipping away at the unknowns of this common COVID-19 symptom. 

Boys Town Ear, Nose and Throat is here to answer some of the most common questions related to loss of taste and smell because of COVID-19, as well as explain when it's time to see a doctor.

Why do people with COVID-19 lose their sense of taste and smell?

Taste and smell are chemical processes. When a substance hits your taste buds, it combines to give you the flavor, sweetness, saltiness, bitterness, etc. However, taste is inseparable from smell. With smell, when a substance is inhaled through your nose, the nerves in the olfactory (smell) area lets you know what it smells like. These two senses work closely together as one.

Professionals believe the primary cause of loss of 'taste' and smell related to COVID-19 is an inflammatory reaction that causes cell damage in the olfactory (smell) area high inside the nose at the base of the brain. Your tasting organs (tongue, taste buds, etc.) remain relatively unaffected by COVID-19.

However, when the cells that surround and support the olfactory nerves are infected with the COVID-19 virus, there can be an inflammatory reaction that damages the olfactory nerves themselves. As a result, the nerves (which are essential for communicating smell messages to the brain) stop working.

Another possible explanation is that congestion and drainage associated with the acute illness can block smells from traveling through the nasal cavity to the nerves in the olfactory area. Though the nerves are still working, the scent never reaches them and therefore you temporarily lose your sense of smell.

There are many other possible causes for temporary or permanent loss of taste and smell that are not related to COVID-19. You can learn more about those in this article. 

How long does it take to regain sense of taste and smell after COVID‑19?

If congestion is to blame for your loss of taste and smell, you should regain these senses once your upper respiratory system has cleared up. If there is olfactory nerve damage, it could be a different story.

Fortunately, professionals believe that most COVID-related loss of taste and smell is only temporary. Data published in the Journal of Internal Medicine suggests that 75-85% of those with COVID-related loss of taste and smell will regain these senses within two months.^[1]

Will my senses change when they return?

It is possible to experience taste and smell differently as your senses return. For most, these differences are temporary, but for some, taste and smell may be permanently altered. 

You may be wondering what causes this change in senses. In some ways, the sense of smell is like playing chords on a piano. When one of the keys you use to play a three-note chord stops working, only two notes will continue making sound and the chord will sound different. In the same way, when some of the nerves in your nose are damaged, your body will continue to use the other nerves to relay the message so your brain may process it differently. 

It is possible for smell nerves to grow back, but they may regrow in a different way, resulting in the same odors somehow smelling different to you.

Some people who lose their sense of taste and smell due to COVID-19 experience a condition where everything smells bad as their senses begin returning. As stressful as this can be to experience, it can be a sign that your olfactory nerves are becoming functional again and you can start retraining them!

What treatment options are available for loss of taste and smell?

The treatment used for loss of taste and smell varies based on the cause. Your doctor will determine the best option for you by conducting a thorough medical history and physical examination, followed by a multiple-choice scratch and sniff test to evaluate your smell acuity. Here are some of the at-home treatment options:

• Clearing up the sinus inflammation accompanying COVID-19
• Saline rinses with a neti pot
• Nasal sprays to reduce inflammation

While therapy options can vary, most patients with acute post-viral smell loss will be offered smell retraining therapy. You can think of this as physical therapy for the nose. The patient will spend time smelling certain scents each day, retraining the nerves in the olfactory tissue to pass along the appropriate messages to the brain. This can be critical in making sure your sense of smell returns as close to normal as possible. 

When should I see a doctor about loss of taste and smell because of COVID?

If you have not regained your sense of taste or smell within two weeks of recovering from COVID-19, you should schedule an appointment with an ear, nose and throat specialist.​

Those who begin treatment for loss of smell shortly after recovering tend to experience better results than those who wait longer.

1. Lechien, J. R., et al. “Prevalence and 6‐Month Recovery of Olfactory Dysfunction: a Multicentre Study of 1363 COVID‐19 Patients." Journal of Internal Medicine, 2021, doi:10.1111/joim.13209.