On the morning after Christmas 2020, Carolyn Hinds woke up and realized she couldn’t smell or taste anything. Other signs of COVID-19, like fever, cough and muscle aches, came in the following days. Those symptoms subsided with time, but her lack of smell and taste did not.
To this day, Hinds, 38, can barely smell anything, and her sense of taste remains warped—sweet things leave a strange aftertaste, salty foods upset her stomach and spice makes her lips and tongue burn but tastes like nothing. “These things will mess with you mentally and physically because it changes the way you experience the world,” she says.
Perhaps worst of all, Hinds’ doctors have said they don’t know how to treat her. “It’s been 10 months,” she says. “I’m kind of thinking this is how it will be [forever].”
Almost two years into the COVID-19 pandemic, lots of people are in Hinds’ position. Smell loss isn’t a COVID-specific phenomenon—it can happen due to other viruses, neurologic disorders, smoking, head injuries and normal aging, among other causes—but the pandemic has greatly increased its prevalence.
The SARS-CoV-2 virus seems to infect and compromise the cells neighboring those that control smell, which can translate to smell loss, explains Dr. Carl Philpott, a professor of rhinology and olfactology at the U.K.’s University of East Anglia. Almost half of COVID-19 patients lose their sense of smell and about 40% lose their sense of taste, according to an international review of previously published studies. (Since much of flavor perception is related to smell, not taste, Philpott says some perceived taste loss may actually be smell loss.) According to preliminary research, as many as half of those individuals also develop what’s known as parosmia, which distorts scents—subbing in, say, the smell of spoiled milk where there should be the aroma of coffee.
“Prior to COVID, we didn’t really have a lot of treatments or interventions that we can use for these patients,” says Paule Joseph, a clinical investigator at the National Institutes of Health who focuses on chemosensory disorders. “Now we find ourselves in the middle of this pandemic, with a group of people recovering with not a lot to offer.”
Not being able to smell might seem like a minor annoyance, at least compared to life-threatening COVID-19 complications. But to write off the loss of smell is to ignore how important it is to share a meal with friends, or appreciate the pine-scented festivity of a Christmas tree. “That inability to partake in the simple pleasure of life really starts to weigh on people and detracts from their overall quality of life and even leads to depression and anxiety and social withdrawal,” says Dr. Zara Patel, a head and neck surgeon and smell-loss expert at Stanford University.
Smell is also linked to a number of important subconscious processes, like choosing romantic partners and parent-child bonding, Patel explains. And there are safety concerns associated with sense loss, like not noticing that food has gone bad or failing to smell smoke when there’s a fire.
For all these reasons, treating smell loss is important—but that’s easier said than done. Anyone can walk into an eye doctor’s office, take a vision test and know if they need glasses. “We don’t have that for the sense of smell, the sense of taste,” Joseph says. “We don’t have clinical guidelines,” which makes it difficult to offer effective treatments.
Even so, some studies have tried to track smell recovery among COVID-19 patients. One, published in October, estimated that 80% of people who lose their sense of smell or taste because of COVID-19 recover it within six months, with adults younger than 40 particularly likely to regain function. But as with so many symptoms of what’s now known as Long COVID, there is a significant subset of people for whom these issues drag on and on.
The field’s standard therapy is what’s known, logically enough, as “smell training.” It involves sniffing strong-smelling substances—typically cloves, rose, lemon and eucalyptus—each day in hopes of re-forging the pathways that mediate scent. But smell training can take weeks or months; for many people, it never works at all.
A trial run by Patel (who has consulted for several medical and pharmaceutical companies, including one that develops ear, nose and throat treatments) suggests that smell training is more effective when patients also rinse their nasal cavities daily with a saline solution spiked with a corticosteroid that can reduce inflammation. But not all experts agree that these drugs are the best option. Philpott recently reviewed prior research on corticosteroids and found little evidence to suggest they help with smell loss among COVID-19 patients.
Next, Philpott is looking into whether nasal drops containing vitamin A could be an effective treatment, based on some promising preliminary research out of Germany. For her part, Patel is studying whether injections of platelet-rich plasma could help restore smell; her study is enrolling participants now. Patel’s research also suggests omega-3 supplements can be effective for some people, but she cautions that she hasn’t studied them specifically among people who lost their sense of smell from COVID-19.
The lack of fail-safe options has prompted some to turn to home remedies. A video that spread on TikTok this past winter, for example, claims that eating burnt orange rind mixed with brown sugar can help. While that trick is probably harmless, if not evidence-based, Patel says she’s heard of far more damaging plans, like using nasal sprays laced with zinc—a mineral that can actually destroy the sense of smell.
The best thing patients can do is see a doctor—preferably one with experience in smell and taste disorders, if possible—shortly after experiencing smell loss, Patel says. “It is just much, much harder to bring someone’s smell back [with] the more time that passes,” she says.
Joseph emphasizes that progress is being made. Patients have come together to develop advocacy groups, like the Smell and Taste Association of North America, that can offer support and push for more research. And because of COVID-19, far more researchers are studying smell loss than ever before. Already, they’ve had some success. A group of researchers recently developed a simple smell test that consists of a card with three affixed patches, only one of which is actually scented. Based on an individual’s ability to pick out which one that is, and their assessments of its strength and characteristics, doctors can start to gauge the severity of their smell loss.
That’s a promising start, Joseph says, but it’s only one step on the road to effective treatments. “We can develop measurements … but we can’t measure for measurement’s sake,” she says. “We have to be able to offer something to patients.”
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Contributor: Jamie Ducharme