- Many people lose their sense of taste or smell after a coronavirus infection, but scientists still aren’t certain who is most at risk.
- These symptoms can also occur in people who had only mild COVID-19 symptoms.
- Researchers say that based on new research, an estimated 37 percent of people had some form of taste loss after a coronavirus infection.
Many people who’ve had a coronavirus infection report losing their sense of smell or taste, symptoms that can affect their quality of life for months after the initial infection.
The severity of these symptoms — which can occur independently — vary from person to person, ranging from a partial to a complete loss. These symptoms can also occur in people who had only mild COVID-19 symptoms.
Dr. Andrew Schamess, an internal medicine physician at The Ohio State University Wexner Medical Center who has been treating patients at the medical center’s Post-COVID Recovery Program, said, “Typically, loss of taste and smell is most common in the early post-COVID period.”
However, “The majority of patients have recovered taste and smell by 6 months,” he said. “Although there are some for whom the symptom persists.”
Estimates vary widely for how common the loss of taste and smell is after a coronavirus infection.
To get a better idea of the true rate of these kinds of symptoms, Mackenzie Hannum, PhD, a postdoctoral fellow at the Monell Chemical Senses Center in Philadelphia, and her colleagues reviewed 241 previous studies looking at the loss of taste after a coronavirus infection.
They focused on this symptom because “there is a common notion that taste loss is not as ‘real’ as smell loss,” Hannum and co-authors wrote in the paper, which was published Feb. 16 in the journal Chemical Senses.
“A lot of the focus has been on the loss of smell. And a lot of the time, questions about COVID-19 symptoms have been about the ‘loss of smell and/or taste,’” Hannum told Healthline. “But these are two completely different senses, so we need to treat them as separate symptoms.”
In their research, she and her colleagues used statistical methods to combine the results from the earlier studies, in what’s known as a meta-analysis.
Based on this, they estimated that 37 percent of people had some form of taste loss after a coronavirus infection.
This fits with what was seen in two earlier meta-analyses, which found that taste loss occurred in
These two earlier meta-analyses also found that loss of the sense of smell occurred in 41 percent and 61 percent of people, respectively.
Hannum and her colleagues found that males were slightly less likely to have a loss of taste, compared with females.
“Females may be more susceptible to taste loss because they are in general more sensitive than males and have more sensory capacity to lose,” the researchers wrote in the paper.
Loss of taste was also more common in people ages 36 to 50, compared with younger people and older adults. The studies that Hannum and her colleagues looked at only included people between ages 18 and 65.
“Why the youngest and oldest groups report less taste loss than do middle-age adults is not currently known,” they write.
However, this doesn’t provide a clear picture of who is most at risk for these symptoms.
“We did look a little bit at age and sex effects to see if those impact the loss of taste,” Hannum told Healthline. “But we don’t have dramatic results to suggest that maybe certain people are more at risk.”
Some scientists are trying to fill in this gap by investigating the mechanisms involved in the loss of the sense of taste and smell after a coronavirus infection.
One study looked at
These researchers also suggest in a separate preprint study that the same mechanism may be involved in the development of long-haul COVID-19, or long COVID.
So far, though, researchers are not able to identify people most at risk of losing their sense of smell or taste after a coronavirus infection.
Schamess said currently there are no medications that can help people who have lost their sense of taste or smell after a coronavirus infection.
But he said some studies show that olfactory retraining can improve many patients’ sense of smell.
This can be done with a set of essential oils, he said. Or you can create a scent kit using foods, herbs, soaps, scented candles, plants, and other items with a strong scent.
For home olfactory retraining, Schamess recommends the following:
- Week 1: Pick three to four scents (cloves, citrus, chocolate, coffee, etc.) and breathe in the smells deeply for 5 to 10 minutes at a time, a couple of times a day.
- Week 2: Pick three to four new scents (eucalyptus, lavender, mint, etc.) and do the same.
- Weeks 3 and 4: Repeat with new scents for each week.
“This may help ‘jump start’ the olfactory recovery,” said Schamess.