The clinical presentation of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection, the virus responsible for COVID-19, extends beyond common respiratory symptoms like cough and fever. Medical professionals have documented a diverse range of extrapulmonary signs, prompting discussion about less-common indicators, including various dermatologic and oral changes. Among these, the term “Covid tongue” emerged, suggesting the virus might manifest in the mouth. Investigating this phenomenon provides insight into the systemic nature of the infection.
Defining the Oral Manifestation and its Recognition Status
“Covid tongue” is a general term describing a collection of possible oral manifestations associated with SARS-CoV-2 infection, rather than a single, uniform condition. Patients have reported symptoms including inflammation (glossitis), swelling, and ulcers or sores on the oral mucosa. The term also encompasses the loss of lingual papillae, which creates smooth, patchy red areas, sometimes resembling geographic tongue. White or yellow patches, often signs of opportunistic fungal infections like thrush, have also been observed.
Though documented in medical literature through numerous case reports, this symptom is not consistently recognized by major public health bodies. Official symptom lists published by organizations like the U.S. Centers for Disease Control and Prevention (CDC) or the World Health Organization (WHO) do not typically include “Covid tongue.” Despite this absence from core public health guidance, scientific studies have noted its presence, with some research indicating that over 10% of hospitalized COVID-19 patients exhibited oral cavity findings.
Timing and Frequency of Appearance
Oral manifestations can appear early, sometimes preceding other systemic symptoms. Studies tracking the onset of oral issues indicate that taste disturbances (dysgeusia) and dry mouth (xerostomia) are frequently reported in the initial stages of infection. However, the more visually distinct symptoms grouped under “Covid tongue,” such as ulcers or significant glossitis, have a varied timeline.
These noticeable tongue changes may appear concurrently with the onset of fever and cough, or manifest days or weeks after initial systemic symptoms begin. The overall frequency of “Covid tongue” is low compared to the hallmark respiratory and flu-like symptoms. Studies looking specifically at tongue lesions, swelling, or ulcers found a prevalence typically ranging from less than 5% to 11.5% in COVID-19 patients. This low frequency and varied timing mean it is not a consistently reliable or common first sign of infection.
Proposed Biological Mechanisms
The scientific hypotheses explaining why SARS-CoV-2 affects the oral cavity center on the virus’s entry mechanism into human cells. The virus utilizes the Angiotensin-Converting Enzyme 2 (ACE2) receptor and the TMPRSS2 enzyme to gain access to host cells. These receptors are abundantly expressed in oral tissues, including the tongue, salivary glands, and oral mucosa, making the mouth a direct target for viral invasion. Direct viral damage may lead to inflammation, swelling, and reduced saliva production, manifesting as dry mouth and gustatory changes.
Oral symptoms can also be secondary effects of the systemic infection. A widespread inflammatory response, often referred to as a “cytokine storm,” can lead to inflammation and ulceration throughout the body, including the mouth. Furthermore, the stress of illness, dehydration, and certain medications can compromise the oral environment. This weakened state allows opportunistic infections, most commonly oral thrush (candidiasis), to flourish, contributing to the appearance of “Covid tongue.”
Recommended Steps Upon Symptom Recognition
If a reader notices symptoms described as “Covid tongue,” they should recognize that oral symptoms alone are not diagnostic of SARS-CoV-2 infection. A variety of other conditions, including viral infections, vitamin deficiencies, or drug reactions, can cause similar changes to the tongue. However, because these symptoms have been linked to COVID-19, obtaining a SARS-CoV-2 test is strongly recommended.
Contacting a healthcare provider is prudent for a proper evaluation of the oral lesions and to determine the necessary course of action. If the test result is positive, the individual should immediately follow local public health guidelines regarding isolation and contact tracing. Treatment for the oral symptoms focuses on managing discomfort, which may involve gentle oral hygiene and prescribed topical treatments to address pain or secondary infections like thrush.