Key Takeaways
The studies surveyed 4,039 COVID-19 patients from 41 countries and confirmed what scientists have observed since the beginning of the pandemic—losing your sense of smell is a reliable early indicator of COVID-19 infection.
Verywell spoke toEric Holbrook, MD, the director of the division of rhinology at Massachusetts Eye and Ear and associate professor at Harvard Medical School, about how COVID-19 affects the olfactory nerves and why your sense of smell may not return right away after you’ve had the virus.
What This Means For YouLoss of sense of smell is one of the most unique and easily observable symptoms of COVID-19. Most people get their sense of smell back quickly, but others do not. If you’re still dealing with a loss of smell and/or taste after having COVID-19, know that new studies have indicated there are potential treatment options like olfactory training and certain drug therapies.
What This Means For You
Loss of sense of smell is one of the most unique and easily observable symptoms of COVID-19. Most people get their sense of smell back quickly, but others do not. If you’re still dealing with a loss of smell and/or taste after having COVID-19, know that new studies have indicated there are potential treatment options like olfactory training and certain drug therapies.
COVID-19 Smell Loss Is Universal
Holbrook tells Verywell that while other virusescan also cause smell loss, in COVID-19 patients, the loss of the sense in the case of COVID-19 is universal instead of targeting certain populations, like older people.
What Causes Loss of Smell?
“It’s really affecting the younger population,” Holbrook says. “The number of teenagers and early adults that are suffering from smell loss after the virus is much higher than what I’ve seen in the past.”
The Role of Your Smell Receptors
The linings of the respiratory tract and nasal passages (the respiratory epithelium and olfactory epithelium) have a lot of ACE2 receptors. Scientists have theorized that theCOVID-19 virus attaches to these receptorsand uses them to get into the cells.
Although ACE2 receptors are not found on the actual olfactory neurons within the nose, they are present in the supporting cells (sustentacular cells). It’s when those cells are attacked that the sense of smell is affected.
Researchers Explain Why Some People with COVID Loss Their Sense of Smell
Sense of Taste
Many people with COVID-19 who were part of the recent studies also reported losing or having changes to their sense of taste. Holbrook says this makes sense because the ability to taste actually relies on multiple sensory inputs.
What Causes Loss of Taste?
COVID-19 attacks the olfactory nerves, which is why many patients report having lost their sense of taste and smell. In rare cases, Holbrook says that some patients report that food has a different mouthfeel, indicating that the trigeminal nerve is also affected.
When Will Smell Return?
Holbrooks says that whileolfactory nervesare some of the only sensory nerve cells in the body with regenerative ability, it’s a slow process. When damage is extensive, recovery of full olfactory capability can take months—if not years.
Hyposmia—partial smell loss—seems to be a widespread effect of COVID-19, and it is probably even more widespread than data-driven studies like Fjaeldstad’s can accurately reveal.
Why Are COVID-19 Long-Haulers Developing Fragrance Allergies?
Some people with COVID-19 do not experience smell loss. Holbrook says that our sense of smell is not an all or nothing sensation—even patients who do not have a complete loss of smell may have diminished capabilities to detect odors, especially when tested using odor concentration tests rather than data based on perceived ability.
Most people who get the virus regain their sense of smell within two to three weeks, but COVID-19 “long-haulers” may deal with the loss for months.
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Helping Patients Recover
Scientists are working on how to help people who have persistent loss of smell after having COVID-19. Olfactory training involves giving patients a kit with four different scents and having them smell each one for ten seconds, twice a day. The treatment has shown promise for treating other cases of hyposmia or dysosmia.
‘Smell Training’ Could Help People Who Lost Their Sense of Smell From COVID-19
A small sample of 27 patients was split into two different groups. Both groups took an initial smell assessment test five weeks after the onset of their smelling loss. One group practiced olfactory training. The second group did the same olfactory training plus a ten-day regimen of oral corticosteroids.
After ten weeks, the participants were retested. The group that took the oral steroids and completed the olfactory training had a significantly higher recovery rate than the group that only did the training. Corticosteroids are not a safe treatment option for everyone, but the study indicated that they might help some people with hyposmia.
The information in this article is current as of the date listed, which means newer information may be available when you read this. For the most recent updates on COVID-19, visit ourcoronavirus news page.
3 SourcesVerywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Parma V, Ohla K, Veldhuizen MG, Niv MY, Kelly CE, Bakke AJ, et al.More than smell-COVID-19 is associated with severe impairment of smell, taste, and chemesthesis.Chem Senses. 2020;45(7):609-622. doi:10.1093/chemse/bjaa041Gerkin RC, Ohla K, Veldhuizen MG, Joseph PV, Kelly CE, Bakke AJ, et al.Recent smell loss is the best predictor of COVID-19 among individuals with recent respiratory symptoms.Chemical Senses. bjaa081.Le Bon SD, Konopnicki D, Pisarski N, Prunier L, Lechien JR, Horoi M.Efficacy and safety of oral corticosteroids and olfactory training in the management of COVID-19-related loss of smell.Eur Arch Otorhinolaryngol. 2021;1-5. doi:10.1007/s00405-020-06520-8
3 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Parma V, Ohla K, Veldhuizen MG, Niv MY, Kelly CE, Bakke AJ, et al.More than smell-COVID-19 is associated with severe impairment of smell, taste, and chemesthesis.Chem Senses. 2020;45(7):609-622. doi:10.1093/chemse/bjaa041Gerkin RC, Ohla K, Veldhuizen MG, Joseph PV, Kelly CE, Bakke AJ, et al.Recent smell loss is the best predictor of COVID-19 among individuals with recent respiratory symptoms.Chemical Senses. bjaa081.Le Bon SD, Konopnicki D, Pisarski N, Prunier L, Lechien JR, Horoi M.Efficacy and safety of oral corticosteroids and olfactory training in the management of COVID-19-related loss of smell.Eur Arch Otorhinolaryngol. 2021;1-5. doi:10.1007/s00405-020-06520-8
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
Parma V, Ohla K, Veldhuizen MG, Niv MY, Kelly CE, Bakke AJ, et al.More than smell-COVID-19 is associated with severe impairment of smell, taste, and chemesthesis.Chem Senses. 2020;45(7):609-622. doi:10.1093/chemse/bjaa041Gerkin RC, Ohla K, Veldhuizen MG, Joseph PV, Kelly CE, Bakke AJ, et al.Recent smell loss is the best predictor of COVID-19 among individuals with recent respiratory symptoms.Chemical Senses. bjaa081.Le Bon SD, Konopnicki D, Pisarski N, Prunier L, Lechien JR, Horoi M.Efficacy and safety of oral corticosteroids and olfactory training in the management of COVID-19-related loss of smell.Eur Arch Otorhinolaryngol. 2021;1-5. doi:10.1007/s00405-020-06520-8
Parma V, Ohla K, Veldhuizen MG, Niv MY, Kelly CE, Bakke AJ, et al.More than smell-COVID-19 is associated with severe impairment of smell, taste, and chemesthesis.Chem Senses. 2020;45(7):609-622. doi:10.1093/chemse/bjaa041
Gerkin RC, Ohla K, Veldhuizen MG, Joseph PV, Kelly CE, Bakke AJ, et al.Recent smell loss is the best predictor of COVID-19 among individuals with recent respiratory symptoms.Chemical Senses. bjaa081.
Le Bon SD, Konopnicki D, Pisarski N, Prunier L, Lechien JR, Horoi M.Efficacy and safety of oral corticosteroids and olfactory training in the management of COVID-19-related loss of smell.Eur Arch Otorhinolaryngol. 2021;1-5. doi:10.1007/s00405-020-06520-8
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