It became obvious to Atlantan Mark Byrd last February that he, his wife and young daughter had come down with COVID-19. All three got sick and lost their sense of smell — one of the hallmark symptoms of the coronavirus.
Byrd had a nasty bout with the virus, but nothing bad enough to send him to the hospital. His wife required a monoclonal antibody infusion because she is immunocompromised, but eventually, all three recovered. His wife and daughter regained their sense of smell, but he didn't. "At the time, I just didn't think too much about it," he says, assuming he would sooner or later.
Then, after four long months, Byrd finally began to pick up on the faintest smells. But after another month went by, he developed a constant metallic taste in his mouth. That's when things began to go south. Byrd's sense of smell fully returned, but it was different. Hand soap smelled like rotting corpses, he says. Roses, like feces. An afternoon swig of beer sent him gagging. No one else around him seemed to pick up on these awful odors and tastes.
Desperate for answers, and a little suspicious that COVID-19 was to blame, Byrd jumped on the internet and discovered he was not alone — or crazy. News accounts were limited, but there were virtually thousands of people in Facebook groups who had recovered from COVID-19 but were left with a disturbing distortion of smell, a condition, he learned, is called parosmia.
What Is Parosmia and How's it Connected to COVID-19?
Parosmia is a disorder characterized by a change in the perception of odors. Most often, as in Byrd's case, the smells are unpleasant, like hand soap smelling like dead bodies and the outdoors like sewage. Conversely, Byrd couldn't detect bad odors that others could.
This odd distortion of scent is being seen in a growing number of people who have contracted COVID-19, lost their sense of smell (a condition called anosmia) and taste (ageusia), and recovered from the virus but never fully regained their sense of smell again, says Dr. Jennifer Grayson, director of otolaryngology research at the University of Alabama at Birmingham. "Parosmia is not classified as a long-haul symptom of COVID. It's more of a complicating and potentially permanent factor of COVID," she says.
Parosmia is closely related to phantosmia, an olfactory hallucination characterized by smelling something that isn't there, such as smelling smoke when there's nothing burning, Grayson says. It can also be intertwined with a distorted sense of taste known as dysgeusia. For example, a member of a Parosmia/Post-COVID Facebook group described toothpaste tasting like "how a landfill smells."
These odd odors and tastes are described by other Facebook group members as "dumpster juice," "hot garbage," "potting soil," "rotting flesh" and "dog." And they can greatly diminish quality of life.
Eating becomes excruciating difficult, as most things that tasted pleasant before they developed parosmia suddenly cause sufferers to gag or vomit. (Imagine trying to eat something that tastes like "rotting flesh.") Because parosmia can linger for months, many of these individuals lose weight and some become depressed and hopeless for fear they will never regain their sense of smell and taste.
How Common Is Parosmia?
Parosmia can be caused by literally hundreds of viruses, including the common cold. It can also be caused by other things, too, like head trauma, brain tumors, neurological conditions, medications, chemical exposure and smoking. But a disproportionate number of COVID-19-related cases have put the disorder in the spotlight, Grayson says.
According to a study published in the February 2021 issue of the journal Nature among COVID-19 patients who had lost the ability to smell, 56 percent reported developing parosmia a median of 2.5 months after initial smell loss. Symptoms were still present six months later in a majority of patients.
So what causes COVID-related parosmia? There are three ways a virus can cause parosmia, Grayson explains. One is from nasal congestion, which can cause swelling and prevent odorant particles from reaching the olfactory nerves. When the swelling resolves, the sense of smell returns.
The other can occur when the virus injures little tentacles of smell nerves called fila or the supporting cells that surround them. The third involves the belief that COVID-19 viral particles can cause inflammation and cell death all the way up the nerve to the brain, causing injury to the olfactory cortex, the part of the brain responsible for the recognition of smell. "And those cells will need to regenerate for smell to come back," Grayson says.
Treatment for COVID-related Parosmia
Much of the data surrounding smell loss recovery predates COVID-19 and includes interventions such as steroid nasal rinses or omega-3 supplementation, both of which are rather benign treatments, Grayson says. But the most promising is smell training.
An international group of experts reviewed existing evidence and, in light of the increase in post-infection olfactory dysfunction related to COVID-19, created a consensus statement published in the Rhinitis, Sinusitis and Ocular Allergy journal for treating the condition that supports smell training for COVID-19-related smell disorders.
Smell training focuses on four scents — floral, fruity, spicy and resinous — that are often tested using the scents rose, lemon, clove and eucalyptus, Grayson says. The actual training involves adding a few drops of essential oils representing each those scents onto a cotton pad, then smelling it for 10 to 20 seconds "and be very focused on your memory of that smell," Grayson says. Individuals should practice smelling each scent a few times before moving on to the next scent, allowing several minutes in between scents to allow their nose to rest.
"It's important to do it every single day and to know that it's not a bad sign of you can't smell it at the beginning. That's expected," Grayson says. "It can take some time before people can start smelling something." After following this routine for six months, the training improves most people's sense of smell, according to researchers of a study published in the journal The Laryngoscope in November 2020. The researchers speculated that the training helped smell pathways recover and regenerate.
Is COVID-19 Parosmia Permanent?
It's too early to say if COVID-19-related parosmia is permanent, Grayson says. "Historically, pre-COVID, 85 to 90 percent of people would regain smell into a normal range within the first year of loss. What that looks like in COVID-19 is a much bigger question mark. We don't really know yet."
The good news is that the return of some sense of smell — albeit unpleasant like in Byrd's case — is likely a sign of scent recovery, she says. "For people who don't have any parosmias and their smell is gone, that's a bigger concern for us. They may not get their smell back at all."
Another encouraging sign is that some members of the Parosmia/Post COVID Facebook group have posted about seeing improvements in their sense of smell and others have reported having a full recovery from their smell distortions.
"I would tell people not to get discouraged," Grayson says. Instead, she recommends people like Byrd start — and continue — smell training. They should also keep up with the latest scientific studies and stay in touch with a local academic hospital. "Because, as things continue to come out in the literature, more interventions will be offered," she says.