Text by Henrylito D. Tacio
Photo from vcuhealth.org and Mayo Clinic
In the past, when people lost their smell and taste, they were not alarmed. But when coronavirus disease 2019 (COVID-19) came into the medical scene, it’s a different story altogether.
Early in the pandemic, it emerged that those infected with the COVID-19 virus were losing their sense of smell – even without displaying other symptoms. So much so that a New York Times feature quoted doctors recommending testing and isolation for people who lose their ability to smell and taste – even if they have no other symptoms.
“Loss of smell can occur suddenly in people with COVID-19 and is often accompanied by loss of taste,” explains Dr. Jill Seladi-Schulman in a healthline.com feature. She adds that, with COVID-19, both symptoms may occur without a runny or stuffy nose.
The keyword is “suddenly.” Dr. Shima T. Moein, study team leader at the Institute for Research in Fundamental Sciences in Tehran, Iran, also used that word. In a Nature report, Moein reported: “Usually, these (COVID-19) patients say they have lost their smell suddenly.”
In the United States, a review of eight studies with a total of 11,054 COVID-19 patients was done. What the reviewers found was that a loss of smell and taste often happened prior to other COVID-19 symptoms.
One good thing about losing your sense of smell at the start of the disease is that it may not result in severe form. “In particular, a loss of smell may also be a potential indicator of a mild case of COVID-19,” Dr. Seladi-Schulman writes. “A study from earlier in the pandemic found that loss of smell was more closely associated with outpatient care as opposed to hospital admission.”
Before probing deeper, let’s take a closer look at why people lose their sense of smell and taste. Colds, sinus infections, and general congestion are the most common causes of temporary loss of smell.
Other things that can lead to loss of smell or taste include the following: allergies, nasal polyps, certain medications, neurological conditions, aging, smoking, trauma to the head, radiation therapy, over-exposure to certain chemicals, and upper respiratory infection.
Among the medications associated with an altered or loss of taste include allergy medicines, antibiotics, antipsychotics, asthma medications, cholesterol medicines, blood thinners, and seizure medications.
“Since our smell and taste buds are so closely linked, any conditions or irritants that cause swelling in the nasal passages can lead to a loss of smell and therefore taste,” explains Dr. Michael Menachof, a well-recognized American physician who specializes in conditions around the head, throat, ear, nose, neck, and face for over 20 years.
“While typically just a temporary nuisance, loss of smell can also pose a dangerous threat, as your sense of smell is responsible for alerting you to dangers like gas leaks, rotten food, or fire. And because it affects your sense of taste, it can also lead to loss of interest in eating that results in unwanted weight loss and malnutrition.”
The nerves responsible for detecting smell (olfactory nerves) are located high and deep inside the nose. “When you have cold or sinusitis, your nose fills with mucus and causes swelling,” Dr. Menachof states. “Because of this mucus and inflammation, the smell can’t reach the top of the nasal cavity – this results in a total or a partial loss of smell.”
Are you losing your sense of smell and taste? Take this test and find out:
Smell: Find something that has a strong, characteristic smell. Foods may be a good option here, such as coffee beans, cinnamon, or fresh garlic. You can also choose to use non-food items like baby powder or a scented candle.
Taste: Locate food with different taste characteristics. Some good examples include things like chocolate (sweet), citrus (sour), ampalaya (bitter), and patis (salty).
If you find that you have trouble picking up on the scents or tastes of your selected items, you may be experiencing a loss of smell or taste.
According to Dr. Bobby Tajudeen, director of rhinology, sinus surgery, and skull base surgery at Rush University Medical Center, a sudden loss of smell can mean a viral condition is at play.
“Usually, when people have a cold, they have congestion and a runny nose, and they can’t breathe through their nose,” Dr. Tajudeen explains. “At the base level that usually causes a temporary reduction in smell. However, once the congestion resolves, in patients with viral induced smell loss, their smell does not recover.”
Now, how will you know that your smell loss is related to COVID-19?
Dr. Tajudeen says that instead of attacking the olfactory sensory neurons, COVID-19 affects the neurons’ supporting cells. Most ordinary people don’t know how this happens, of course. The telltale sign is when the smell loss occurs.
“With most viral infections, smell loss will occur after the other viral symptoms – the nasal congestions and runny nose – have come and gone. With COVID-19, smell loss is one of the first signs of infection,” Dr. Tajudeen says.
The question is: How can COVID-19 cause you to lose your sense of smell or taste? Until now, no one can answer this question, but there are several theories forwarded.
“SARS-CoV-2, the coronavirus that causes COVID-19, binds to a protein called ACE2 that’s found on the surface of potential host cells,” Dr. Seladi-Schulman says. “ACE2 is abundant in cells found in your nose and mouth.
“It’s possible that the virus could directly invade the nerve cells associated with your senses of smell and taste. However, a recent study in the journal Science Advances has cast doubt on this idea.
“Researchers failed to find ACE2 on nerve cells that detect scents. Instead, they found ACE2 on cells that surround and support these nerve cells. It’s possible that infection of these surrounding cells could lead to levels of inflammation or damage that impact your ability to smell.
Less research has been done on how COVID-19 specifically affects taste. Since the loss of smell and loss of taste often occur together, it’s currently believed that people with COVID-19 likely experience loss of taste as a consequence of loss of smell.
Now, if loss of smell and taste is the first symptom you experience, it’s a good indicator to get tested and quarantined. “Patients with smell loss are normally at home recovering and not admitted into the hospital or on a ventilator,” Dr. Tajudeen says.
Another major difference is the length of smell recovery. “With other viruses, recovery could take months and sometimes even years,” Dr. Tajudeen says.
The earliest is about four weeks. “During a recent study, we looked at about 1,000 COVID-19 patients. Based on their own symptom reporting, about 78% of those with total smell loss had completely recovered their smell at around the four-week mark.”
About 20% of those patients did not recover their smell after four weeks.
The Mayo Clinic calls those who lose their sense of smell as having smell dysfunction. “In most cases, smell dysfunction recovers quickly,” explains Dr. David Valencia, an otorhinolaryngologist. “However, it can take months. In a minority of cases, recovery can be incomplete with lasting impairment.
“While no proven treatment is available, olfactory training is recommended,” Dr. Valencia continues. “Topical corticosteroid sprays also are often used in short-term treatment, but they are unlikely to help outside of the acute illness period. Clearly, the best treatment is prevention, such as wearing a mask, practicing social distancing and getting vaccinated for COVID-19.”
