Lost Sense of Smell May Be a Symptom of Coronavirus, According to Experts

As knowledge about the newest coronavirus, COVID-19, continues to grow, so does the list of potential symptoms. While the major and most common symptoms are still fever, dry cough, and shortness of breath, a recent plea from ear, nose, and throat specialists points to a sudden loss of smell and taste as another symptom—something which, just last week, I started experiencing.

Let me back up: Six days ago on vacation, I sat in a Costa Rican cabin eating two eggs I’d fried for breakfast before a long day of hiking in the rainforest. At first, I thought maybe eggs just weren’t so eggy in Costa Rica. But then I ate some of the reddest, most beautiful strawberries and they tasted like nothing. The fish tacos I had for dinner that night were also tasteless, and so was the next day’s breakfast, lunch, and dinner.

But it wasn’t just my taste that had gone MIA; I also couldn’t smell anything (your senses of taste and smell are extremely linked, FYI). Coffee, mango, and the damp earth and plants I was hiking through all had absolutely no odor. Even the bubbling hot springs my girlfriend and I visited, which famously reek of sulphur, smelled like nothing to me.

Maybe I should have thought more deeply about my suddenly missing senses amid this global pandemic, but at the time loss of smell and taste were not symptoms we were told to look out for. (Believe me, I Googled it obsessively—even while on vacation.) Then, days after I got back to the states, I started learning of others reporting a loss of smell and taste—and experts have begun connecting those symptoms to COVID-19.

In a new joint statement on behalf of ENT UK, a professional membership body of ear, nose, and throat surgeons and specialists in the United Kingdom, experts warn of evidence that suggests loss of smell may be a symptom of COVID-19. Going a step further, co-authors of the statement, Clare Hopkins, president of the British Rhinological Society, and Nirmal Kimar, president of the British Association of Otorhinolaryngology, urged anyone who has lost their ability to smell or taste to self-isolate for seven days. "I think these patients may be some of the hitherto hidden carriers that have facilitated the rapid spread of COVID-19," the doctors wrote. "Unfortunately, these patients do not meet current criteria for testing or self-isolation."

During a news briefing Monday, Maria Van Kerkhove, COVID-19 technical director for the World Health Organization, also shared that the loss of these sensations may be an indicator of a coronavirus infection. "We've seen quite a few reports now about people in the early stages of disease may lose the sense of smell, may lose the sense of taste," she said, adding that this is something the WHO is currently looking into.

According to the co-authored statement, anecdotal cases of anosmia—commonly known as smell blindness, or the inability to detect one more more smells—related to the current coronavirus pandemic are rising. Hopkins and Kumar wrote that anosmia is reported in two out of three confirmed cases of COVID-19 in Germany and 30 percent of the confirmed cases in South Korea.

Loss of smell and taste seem particularly noticeable in mild cases of COVID-19, when patients have few or no other symptoms. “There have been a rapidly growing number of reports of a significant increase in the number of patients presenting with anosmia in the absence of other symptoms—this has been widely shared on medical discussion boards by surgeons from all regions managing a high incidence of cases,” the authors wrote. Because people have no other symptoms, they may be unknowingly spreading the virus. While we all should be practicing social distancing, the doctors say it’s especially important for anyone who suddenly cannot smell or taste to stay home.

In general, viruses often cause anosmia or hyposmia (a partial loss of smell), which can lead to dysgeusia (a distorted sense of taste). Alfred Iloreta, MD, an otolaryngologist at The Mount Sinai Hospital says that post-viral anosmia is a leading cause of loss of smell in adults. “Almost 40 percent of patients who have complete loss of smell have some kind of respiratory infection or virus,” he says.

Although experts don’t know for sure what’s causing COVID-19 to affect some patients’ ability to smell and taste, some viruses can affect the olfactory sensory neurons themselves, says Donald Wilson, PhD, a neurologist and physiologist at New York University Langone School of Medicine. "These are the cells that sit up in the back of your nose, and when an odor molecule binds to receptors on their surface, the olfactory sensory neuron (OSN) sends a signal to the brain," says Wilson. That is, essentially, how we typically sense smells.

Those sensory neurons don’t tend to live very long because they exist in a harsh environment—all the things that go up your nose impact them)—so each cell dies and gets replaced by a new one every couple of months. But, importantly, the cells don’t all die at the same time, so you never notice when a few are shed.

Some viruses, however, cause OSNs to die more quickly. “If OSNs die then odor signals can't get to the brain and we lose our sense of smell,” says Wilson. “Since our perception of flavor is mostly olfaction, many people will also complain of loss of taste.” That loss of taste is actually more loss of flavor, however. Since we still have taste buds, we can still distinguish whether something tastes sweet, bitter, sour, salty, or savory. “We just lose the variety of vanilla, coffee, Merlot, etc that is due to olfaction,” says Wilson.

It's also possible, however, that the virus is merely dulling our senses of smell and taste in the same way that a common cold or flu does, through simple decrease of airflow through the nose. Cold-like symptoms that cause inflammation or excess mucus in our nostrils limit the ability for odor molecules to reach these receptors, and therefore make it more difficult to smell something and sense variation in flavors, says Wilson.

The slightly less concerning news? Patients who lose their senses of smell and/or taste should get those senses back—whether it's related to COVID-19 or another ailment. But something to keep in mind amid the coronavirus outbreak: If you suddenly become unable to smell your coffee in the morning, it's likely best to call your doctor, start self-isolating, and keep an eye out for any other symptoms that arise.

As for me, I self-quarantined with my girlfriend as soon as we returned from our Costa Rican trip, so I haven't been in contact with anyone other than her since our return home. Upon learning that a lost sense of smell and taste could be indicators of COVID-19, I immediately contacted my health insurance provider to put me in contact with a doctor for evaluation to see if I am eligible for a coronavirus test. Though I've yet to hear from a doctor, I am still under self-quarantine, and I have regained my sense of taste and smell.

The information in this story is accurate as of press time. However, as the situation surrounding COVID-19 continues to evolve, it's possible that some data have changed since publication. While Health is trying to keep our stories as up-to-date as possible, we also encourage readers to stay informed on news and recommendations for their own communities by using the CDC, WHO, and their local public health department as resources.