Lost Your Sense of Smell Due to COVID-19? Here’s What to Do

Smell training is helping those with coronavirus-related anosmia restore this vital sense.

A Texas family’s house burned to the ground on January 15 because family members suffered from a common hallmark of COVID-19—the sudden, total loss of smell.

The only family member who didn’t lose the ability to smell was 17-year-old Bianca, who smelled “burnt plastic” in the middle of the night, roused the family, and saved them from being engulfed by flames.

Loss of smell, referred to as anosmia, affects 74 percent of all people infected with the novel coronavirus and 86 percent of those with mild cases of COVID-19, according to findings recently published in the Journal of Internal Medicine

The loss of smell seems a mild symptom considering the massive loss of life inflicted by the virus in the last year, but as the Texas fire underscores, the by-product of the virus is more than just a curious annoyance. 

“When your house is burning down because you can’t smell the smoke, and when you get food poisoning because you can’t smell the rotten food or milk, this is a life-threatening issue,” says Brian Rotenberg, an otolaryngologist (ear, nose, and throat specialist) at London Health Science Centre in Ontario, Canada.

According to the study, 95 percent of those who lose their smell from COVID-19 will regain the sense within six months. A small percentage, however, will experience prolonged anosmia, and another small portion of people will develop another condition called dysosmia, where they detect phantom smells or perceive normal smells with distorted and altered effects. 

Almost like nasal physiotherapy, you can re-teach the nose how to smell.

Even though the overall percentages are small, in absolute numbers, the number of people suffering is actually quite large, says Rotenberg, because more than 113 million people worldwide have contracted the virus as of the end of February. 

For those long-COVID patients who have ongoing olfactory dysfunction, there are techniques and smell training programs which can be used to retrain and restore this sense. “Almost like nasal physiotherapy, you can re-teach the nose how to smell,” Rotenburg explains.

Here’s your smell training workout

Thomas Hummel, a German otolaryngologist who studies smell and taste, proposes smelling four different smells twice a day. He chose the strong, striking smells of rose, clove, eucalyptus, and lemon, based on the historic “odor prism,” which, similar to the color wheel for primary colors, breaks down the human sense of smell into the primary scents burnt, spicy, resinous, foul, fruity, and flowery. 

“You know what lemon should smell like, but if you can’t smell it, then you’re thinking about lemon experiences such as lemon cake or lemon meringue pie,” Rotenberg says. And while you do this, what’s happening in the background, physiologically, is that “you are decreasing your smell receptor threshold to lemon so (the receptors) can pick up smaller amounts of molecules required to initiate a nerve response.”

“There is fairly strong evidence behind smell training as an effective means of improving sense of smell,” Rotenberg says. This is effective for many causes of anosmia but has been proven to be most effective for post-infectious cases.

Rotenberg believes that there is a mindfulness and wellness component to the training that some people enjoy and that may actually help with the training. He explains that during smell training, people need to “carve out ten minutes, in a dark room, with no noise, just themselves: It’s basically meditation.” 

“There is fairly strong evidence behind smell training as an effective means of improving sense of smell.”

While in that dark room, the essential oil is held up to the nose and inhaled naturally, not aggressively. Each fragrance is smelled for 10 seconds before rotating to the next fragrance.

COVID-19 doesn’t cause nasal congestion the way other causes of olfactory dysfunction do. The nasal cavity is lined with epithelial cells. Those cells have olfactory receptors on the surface that detect odors. Odors need to be carried up to the receptors on the cells for someone to sense that smell. Other viruses, like those that cause colds, cause inflammation of structures in the nasal cavity, leading to the production of phlegm that can obstruct odor molecules, thereby preventing them from reaching the receptors. In COVID-19, there is no inflammation of these structures, suggesting “it’s a problem at the cellular level,” says Leigh Sowerby, an otolaryngology colleague of Rotenberg who has an expertise in rhinology and sinonasal disorders.

The hypothesis is that loss of smell occurs because of direct insult to the olfactory epithelium. ACE2 receptors are concentrated on both the nerve fibers and olfactory cells, but the virus is likely affecting the olfactory cells because true neural death is not occurring in cases related to COVID-19. Sowerby explains that if this were damage to the nerve “you’d have to have nerve regrowth which would take much longer, and that fits more with the traditional post-viral anosmia that takes a long time to get your smell back.” Recovery of lost sense of smell from COVID-19 is occurring more quickly compared to loss of smell from other viral illnesses.

“COVID-19 patients experience a sudden loss of smell in the absence of nasal congestion and that’s unique,” Sowerby says, when contrasting it with other causes of loss of smell. 

In correctly identifying COVID-19, a loss of smell without nasal congestion “is one of the most sensitive markers—more sensitive for COVID-19 than fever or cold,” Sowerby says. Some people realize they caught the bug even before they are tested by virtue of loss of smell alone.

Rotenberg and Sowerby have lots of advice for people who lose their sense of smell. First and foremost, make sure to observe expiration dates on food. Also, make sure that all smoke detectors are working and have new batteries. 

Some people experience unintentional weight loss. They recommend supplementing with important vitamins, such as vitamin A, to prevent issues that can be related to deficiencies.

The tragedy of losing your taste

Though taste is less of a survival tool than smell, it is intimately linked with smell, and loss of taste can have a dramatic impact on someone’s quality of life. Recent studies show that taste was affected in 46 percent of people with COVID-19. It occurs more frequently in mild cases. Loss of taste is not life threatening, but it can severely impact someone’s quality of life. 

Although scientists have some understanding of how COVID-19 affects sense of smell, they have little idea about how this affects taste.

“Taste is mostly smell,” Rotenberg explains. “Your tongue can only detect bitter, sweet, or salty without smell, but the symphony of flavors you get when you eat, that’s all olfaction. If you don’t get the olfactory sense component, you’ve lost your joy of food, and this can sometimes cause depression in people,” he adds. 

Finally, while loss of smell could be a strong indicator of coronavirus infection these days, the symptom itself is by no means specific to COVID-19. “If smell never comes back, it’s worth getting this looked into,” Rotenberg says. “It could be something benign but troublesome like sinusitis, but it could also be something serious like a tumor.”

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