(CNN) – About 86% of people with mild cases of Covid-19 lose their sense of smell and taste, but recover within six months, according to a new study among more than 2,500 patients from 18 European hospitals.
A case of Covid-19 is considered moderate if there was no evidence of viral pneumonia or loss of oxygen and the patient was able to recover at home.
The sense of smell reappeared after an average of 18 to 21 days, the study found, but about 5% of people did not regain smell function at six months.
Anosmia, which has a loss of smell, and therefore taste, is suggested as an early sign of Covid-19. It can occur without any prior warning, not even a stuffy nose.
“Anosmia has been seen especially in patients who have finally tested positive for the coronavirus without any other symptoms,” according to the American Academy of Otolaryngology-Head and Neck Surgery.
Moderate to severe Covid-19
Comparatively, the study found that only 4% to 7% of people with moderate to severe symptoms of Covid-19 lost their ability to smell and taste.
People with moderate Covid-19 had ‘clinical signs of pneumonia’, such as cough, fever and breathing problems. Those with critical cases of the disease had severe respiratory distress, and were more likely to be older and had ‘high blood pressure, diabetes, stomach disorders, kidney, respiratory, heart, liver and neurological disorders.’
The study found that the study, published in the Journal of Internal Medicine on Monday, found a higher rate of olfactory dysfunction in younger patients.
How to test your sense of smell
Is there anything you can do at home to test if you are losing the smell? The answer is yes by using the ‘jellybean test’.
“You take a jelly tree in one hand and with the other hand you hold your nose tightly so you get no airflow,” Steven Munger, director of the Center for Smell and Taste at the University of Florida, told CNN in a previous interview.
‘You put the jelly in your mouth and chew it. Suppose it is a fruit-flavored jelly tree: if you get the saltiness plus the sweetness of the jelly bean, you know you have a functional taste, ‘Munger said.
Then suddenly release your nose while you are still chewing. If you have a sense of smell, you will suddenly get all the smells and you will say ‘Oh! it’s a lemon jelly, ‘or’ Oh! it’s cherry. “It’s really a very dramatic, quick ‘Wow’ response,” he explained.
“So if you can go from sweet and sour to full taste and know what the taste is,” Munger said, “then your sense of smell is probably pretty good.”
The scientific name for this process is retro nasal olfaction, where the odors from the back of your mouth flow through your nasal pharynx and into your nasal cavity.
But what if you do not have a jelly bean? You can also use other foods, said dr. Erich Voigt, director of the sleep otolaryngology division at NYU Langone Health, said in a previous interview.
“The pure sense of smell would be if you smell a specific substance that does not stimulate other nerves,” Voigt said. “If you can smell ground coffee or coffee, or if you can smell someone peeling an orange, it’s the smell.”
However, you need to be careful because it is easy to think that you are using your sense of smell when you are not, Voigt said.
“So for example, ammonia or cleansing solutions stimulate the trigeminal nerve, which is an irritating nerve,” he said. And so people will think, ‘Oh, I can smell Clorox, I can smell ammonia, which means I can smell. ‘But no, that’s not correct. They do not actually smell, but use the trigeminal nerve. ”
Do not know yet if you can do it? Check the internet for medical based scraping and sniffing tests.
Odor loss is common
Of course, not everyone who takes an odor test will have coronavirus. Any respiratory virus, such as colds or flu, will temporarily affect the smell and taste, sometimes even permanently.
“The amount of swelling that can be caused by the viral effect in the nose can prevent the odor particles from reaching the top of the nose where the olfactory nerve is,” Voigt said. “If the swelling goes down, the sense of smell can return.”
But there are also neurotoxic viruses, some of which are in the common cold category, Voigt said.
“If they are neurotoxic, it means they are damaging the olfactory nerve and it is becoming essentially dysfunctional,” he added. “Many of the cases can get odor again over time, but sometimes it’s a permanent loss.”
A partial or complete chronic odor loss is incredibly common, Munger said, and it affected millions of Americans long before the new coronavirus erupted at the scene.
“About 13% of the population has a significant odor or taste impairment,” he said.
In addition to colds and flu, there are also causes of odor loss, nasal polyps, tumors, neurodegenerative diseases such as Alzheimer’s or Parkinson’s, and traumatic brain injury or head trauma, including whiplash.
“If someone has been in a car accident or had a whiplash injury or head injury, it can also affect the nerves if they go from the brain to the nose,” Voigt said. “Thus, a whiplash injury can cause a permanent loss of sense of smell.”
The loss of taste is usually associated with the loss of smell because we rely on smell to identify flavors. But there can also be medical reasons: some medicines can affect the taste; chemotherapy and radiation therapy can certainly disrupt the taste; and then there is physical damage, such as nerves being cut off during dental surgeries.
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