'COVID tongue' may be another early indication of coronavirus infection

The list of COVID-19 symptoms ranges from congestion to diarrhea to the losses of smell and taste.

Now, researchers are investigating another possible symptom that some people are calling "COVID Tongue." The symptom, which is considered relatively uncommon, appears as tongue discoloration, swelling, ulcers and other mouth issues. 

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A study of Spanish COVID-19 patients published in the British Journal of Dermatology last week is one of a handful bringing attention to the issue.

Researchers found 78 of 666 patients involved in the study — more than a tenth — experienced "oral cavity findings." 

Of the 78 patients, 11% had inflammation on the bumps on the top of the tongue. Others experienced mouth ulcers, "patchy" areas around their tongues, tissue swelling in their mouths or swollen tongues with inflammation and indentations on the tongues' sides.  

Scientists from the Czech Republic studied 26 people with mild or moderate COVID-19 who experienced ulcers between April and June 2020. 

They found as many as seven half-centimeter-long ulcers on each patient, usually located on the sides of the patient's tongue, according to Business Insider. However, patients who began using antimicrobial mouthwash noted that their mouth ulcers disappeared after one or two weeks. 

"COVID tongue" also gained recognition after Tim Spector, a British researcher who is studying COVID-19 warning signs, tweeted about the growing number of COVID-19 patients with mouth problems. 

"Seeing increasing numbers of Covid tongues and strange mouth ulcers," wrote Spector, a genetic epidemiology professor at King's College London. "If you have a strange symptom or even just headache and fatigue stay at home!"

Spector said he thinks as many as 1 in 500 coronavirus patients may experience the symptom, according to NBC News. He tweeted that 35% of COVID-19 patients have non-classic symptoms "in the first three days when most infective," placing "COVID tongue" alongside skin rashes and "COVID toes."

The U.S. Centers for Disease Control and Prevention does not recognize "COVID tongue" as a coronavirus symptom. Several other yet-to-be-confirmed symptoms, like rashes and COVID toes, are not recognized either. 

At one point, the loss of smell and taste seemed an unusual addition, too. But it is now seen as a fairly reliable indicator of infection. As many as 80% of people who have COVID-19 reportedly experience the loss smell or taste.

However, "COVID tongue" is still much less common than smell or taste problems. 

Dr. Sunitha Posina, an internal medicine physician in New York City who spent time working on the front lines, said she hasn't seen any coronavirus patients with these tongue or mouth problems.

"I have treated a good number of COVID-19 patients, but none of my patients had these symptoms, and I didn’t hear anyone I know complaining of it either," Posina told InStyle. "It's possible that it simply went unnoticed, especially if it was mild."

Other viruses, including HPV, syphilis and herpes can cause oral lesions, she said. So can foods. But Posina added that it's unlikely "COVID tongue" would be the only symptom an infected person ends up having. 

"You're most likely to have a few other symptoms along with 'COVID tongue' such as cough, fever, loss of sensation of smell and/or taste," she said.