Sniffing out answers

How Smell Loss Can Be a Sign of the Coronavirus

The CDC added loss of smell to its list of COVID-19 symptoms. We asked a local ENT why.

By Catherine Wendlandt May 13, 2020

By now, you can probably rattle off the basic symptoms of COVID-19—fever, cough, shortness of breath—in your sleep. However, the Centers for Disease Control and Prevention recently added several more potential symptoms: fever, chills, muscle pain, sore throat, and a new loss of taste or smell.

Yes, the newer symptoms do sound like a common cold, so we asked a local expert, Dr. Abib Agbetoba, the director of the Texas Allergy and Sinus Center, to break down what the difference is between a standard summer cold stuffiness that keeps you from knowing for sure whether that new natural deodorant is actually working, and the loss of the sense of smell that has been found to sometimes come with COVID-19.

The coronavirus “presents like any other viral symptom or viral cold,” Agbetoba says.

But it's not a symptom you should just dismiss out of hand if you notice that your sniffer isn't as sharp as it usually is. The loss of smell in COVID-19 patients has been found to be much more profound than a stuffy nose. There's some evidence that this symptom could be a sign of the virus having damaged the central nervous system, a possibility that may indicate other problems in the future, according to various reports. Agbetoba, an otolaryngologist, (also known as an ear, nose, and throat—ENT—doctor), says it’s estimated that 34 to 68 percent of COVID-19 patients worldwide report some degree of smell loss.

In fact, if you just have loss of smell, and no other symptom of a cold, you should strongly consider getting yourself tested and should take all possible precautions when dealing with others until you know for sure whether you have the disease or not.It's possible that other symptoms could show up first, he says, but the loss of smell could also be your only symptom. “It can present before any other symptom [of the coronavirus], it can present as the only symptom, or can it can present with those other symptoms.”  

But how does this sense work and how is this novel coronavirus affecting people's ability to smell? We got Agbetoba to walk us through how smell works under normal conditions and what it could mean if you do lose this sense to the virus. 

Let’s go through some basic anatomy

High up in your nasal cavity, near the base of your skull, you have nerve fibers, called the olfactory nerve, that control your sense of smell. When you get sick with a cold, your nasal passages swell up, blocking the path odorants take to get to your olfactory nerve, which is why you can’t smell. 

Agbetoba says it’s still really early to know for sure with the novel coronavirus, but “we think what happens is that the virus causes inflammation and swelling inside the nose that prevents odorants from accessing the nerve fibers that help us with sense of smell.” 

How do I know that I’ve lost my sense of smell?

We’ve all been there when we’ve had a cold with a runny or stuffy nose, but most people don’t realize they also lose some of their sense of smell, Agbetoba says. You’re probably not strolling through parks and smelling flowers if you’re feeling lousy. But, your sense of smell is also closely linked to you sense of taste. “Likely, when you have a loss of smell, you’re also probably noticing that the chicken soup doesn’t taste as well, or the wine doesn’t taste like it normally would.”

When should I be worried about my loss of smell?

In most situations, these symptoms go away within a week or two when you have a cold, Agbetoba says. When smell loss lasts longer than that, that’s when things can get serious.

If there’s inflammation or destructive changes happening to the olfactory nerve itself, then it becomes harder to return your normal baseline sense of smell. The longer you wait to get treated, then the less likely you’ll be able to completely regain your sense of smell.

As for COVID-19, doctors don’t know yet if the virus will cause long-term smell loss, Agbetoba says. 

What else could a loss of smell mean?

“Anything from nasal congestion to increased mucus production, because of the swelling that can occur within the nasal cavity, can cause loss of smell,” Agbetoba says.

Smell loss can result from a laundry list of conditions. Some are as mild as allergies or acute sinusitis (a cold), but it could also be an early sign of general cognitive disorders, like Alzheimer’s.

However, Agbetoba doesn’t want people to panic. “I would not have the general populations go around sniffing coffee beans, vanilla extract, and things like that,” he says. “But what I would say is if you feel like you’ve lost some sense of smell, and it’s gone on for more than a few weeks, then it’s important to reach out to your ear, nose, and throat doctor.”

Why should I care about my sense of smell?

Smell might not be the top priority of the five senses, but “We find out that through studies that it actually has a significant impact on patients’ quality of life,” Agbetoba says. After all, if you go out and order a $40 steak, then you want to be able to enjoy it.

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