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An Indiana University scientist discusses the loss of smell related to COVID-19 and a research project that's helping patients connect.

The nose knows: Loss of smell linked to COVID-19

It seems as though an unusual symptom is presenting itself among some COVID-19 patients—and sometimes, it’s the only symptom.

Sachiko Koyama, PhD, said that recent studies suggest that anosmia, the loss of the sense of smell, is a major symptom of COVID-19.

Koyama is a former associate scientist at Indiana University School of Medicine, whose expertise is in the chemical signaling related to olfactory sense. Since the coronavirus outbreak, she has been on the virtual frontlines of the pandemic helping to monitor a Facebook group called COVID-19 Smell and Taste Loss.

The group was launched on March 24, 2020, by representatives of a charity trust in the United Kingdom called It now has more than 2,000 members with dozens more joining each day. As a group administrator, Koyama helps oversee its activity and collect data. And the response is overwhelming.

“When the group started in March, COVID-19 was new,” said Koyama. “At first it was overwhelming analyzing the reports, but then I started to see the same patterns of the process, and I started to provide advice to the patients.”

Patients in the group represent diverse age groups, but the majority range between 20 and 40 years old. While about half of the patients report additional symptoms, such as headache, fatigue, fever, coughs, and body aches, Koyama approximated that 45 percent of those in the group do not report any symptoms other than anosmia and/or dysgeusia—the loss of taste. According to Koyama, loss of smell and taste are seen but not the typical symptoms in other viral illnesses.

Furthermore, Koyama said that patients who only report anosmia and/or dysgeusia seem to recover their senses much faster than those who report other symptoms. And patients who do experience other symptoms appear to lose their senses of smell and taste an average of four days after the onset of other symptoms.

The causes of anosmia and dysgeusia vary and could be linked to tissue damage or inflammation caused by coronavirus that interferes with chemical signaling. Koyama said that some patients complain of nose pain while others report dark phlegm or “phantom” smells, picking up on scents that aren’t present to others. She said that since symptoms and severity are different among patients, the mechanisms that lead to the condition are likely varied as well.

Whatever the cause, it’s unclear exactly how long COVID-related anosmia will last.

“Usually it takes a long time, even years, to recover from anosmia. However, some of the COVID-19 patients with anosmia seem to recover their senses early. I have seen patients who reported their recovery in less than two weeks among the Facebook patient group,” said Koyama. “There are of course patients who have reported experiencing anosmia since January or February. As the coronavirus outbreak started this spring, we don’t yet know how long it will take for them to recover.”

Ultimately, Koyama said that she hopes this and other studies will better define the characteristics of coronavirus in order to achieve earlier diagnoses and prevent the spread in communities around the world. While there is more work to be done, Koyama said she is glad that the group is bringing people together and that she sees an unexpected silver lining of a pandemic during the 21st century: global networking and communication.

“The largest benefit of the Facebook group is the ability to communicate with other patients,” she said. “All of them are scared of what will happen next, worried if their symptoms are what are supposed to happen, worried if they will get their senses back and, if so, when. There are pregnant women worried about their babies and parents worried about their small children who are showing symptoms. They’re anxious and desperate, but they’re able to support each other from all over the world, and I feel glad to be able to support them through this Facebook group.”

Koyama is a member of the Global Consortium for Chemosensory Research (GCCR), a global network of scientists and clinicians at work to better understand loss of taste and smell related to COVID-19. The GCCR is conducting a survey, which is available in 29 different languages, among people who have lost their sense of smell and/or taste. That survey is available on the GCCR website.

The views expressed in this content represent the perspective and opinions of the author and may or may not represent the position of Indiana University School of Medicine.
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Sara Buckallew

Communications Coordinator

Sara Buckallew works in the Dean's Office of Strategic Communications. As a communications coordinator, Sara supports internal and external communication needs for the Herman B Wells Center for Pediatric Research and the Center for Diabetes and Metabolic...