Dry Mouth: A Common Early Symptom of COVID-19 Infection

Dry Mouth: An Overlooked Symptom of COVID-19

The COVID-19 pandemic has been raging for over two years now, and the medical community continues to learn more about this novel coronavirus. One of the most interesting aspects of COVID-19 is the wide variety of symptoms it can cause. The once thought to be "main" symptoms like fever, cough, and shortness of breath have proven to not always be present in COVID-19 cases. In fact, some of the most commonly reported symptoms are not typical of other respiratory illnesses. One of the most overlooked symptoms that many COVID-19 patients experience is dry mouth.

What is Dry Mouth?

Dry mouth, also known as xerostomia, is a condition characterized by decreased saliva production. Saliva plays an important role in begin moisturizing and lubricating the oral cavity, aiding in digestion, maintaining tooth integrity, and protecting against infection. When salivary flow is impaired, it can lead to a whole host of issues in the mouth and throat. Symptoms of dry mouth include:

• Difficulty swallowing or speaking
• Burning sensation or soreness in the mouth
• Cracked lips
• Halitosis (bad breath)
• Dry, rough tongue
• Increased dental decay

Dry mouth is typically caused by medications that inhibit saliva production, radiation therapy to the head and neck, autoimmune diseases like Sjogren's syndrome, or as a result of aging. Environmental factors like low humidity, smoking, and mouth breathing can also lead to insufficient salivary flow. Now, COVID-19 infection is emerging as another potential cause of dry mouth.

Prevalence of Dry Mouth in COVID-19

Many early reports out of Wuhan, China and Italy noted that COVID-19 patients were complaining of taste disorders and dry mouth. In one study out of Italy, up to 88% of hospitalized COVID-19 patients self-reported smell and taste impairments. Loss of taste, also known as ageusia, was more prevalent than loss of smell or anosmia. Researchers pointed out that disturbances to taste typically stem from dysfunction of the salivary glands and altered saliva composition. Multiple other studies have also discovered taste and smell disorders in COVID-19 patients, even among mild-moderate outpatients. This indicates oral involvement in COVID-19 is common.

Further evidence for dry mouth emerging during COVID-19 infection comes from histological analyses. Autopsies have revealed extensive inflammation and structural damage within the salivary glands of COVID-19 deceased patients. The researchers noted marked acinar cell necrosis and lymphocytic infiltration concentrated in the salivary glands. This pathology was not seen other tissue samples. They theorize SARS-CoV-2 may directly infect and replicate within salivary gland tissue, causing cellular damage.

Mechanisms Linking COVID-19 and Dry Mouth

There are several ways in which COVID-19 could plausibly give rise to dry mouth:

1. Direct viral infection of salivary glands - As mentioned, autopsy studies indicate the SARS-CoV-2 virus appears to infiltrate and replicate within salivary gland tissue.
2. Increased angiotensin converting enzyme 2 (ACE2) expression - Salivary glands have high levels of ACE2 receptors, which enable SARS-CoV-2 viral entry into host cells.
3. Oral inflammation - COVID-19 elicits widespread inflammation, which when occurring in the oral cavity, can impair saliva secretion.
4. Medications - Certain COVID-19 therapeutic drugs like antivirals and hydroxychloroquine have dry mouth as a side effect.
5. Critical illness - Severe illness alone puts patients at increased risk of dry mouth due to dehydration and oxygen therapy.

Together, these disease-related factors make decreased salivary flow common among COVID-19 patients, especially hospitalized cases. However, even mild outpatient cases report dry mouth symptoms.

Dry Mouth as an Early Symptom of COVID-19

Intriguingly, several studies have shown taste disorders and dry mouth often manifest before more recognized COVID-19 symptoms like fever and cough. COVID-19 patients frequently self-report loss of taste or dry mouth as being one of their earliest noticeable symptoms:

• In a survey of over 5000 COVID-19 positive individuals, taste loss occurred prior to cough, fever, and shortness of breath in 30% of respondents.
• Another questionnaire of nearly 2000 COVID-19 patients found 34% experienced impaired taste/smell 2-14 days before respiratory symptoms began.
• Analysis of a COVID-19 exposure cluster revealed dry mouth was one of the very first symptoms noticed by a majority of infected individuals.

These findings suggest dry mouth associated with COVID-19 may manifest during the initial viral incubation period, even before overt clinical presentation. For some patients, loss of taste is the defining and only presenting symptom of their COVID-19 infection.

How to Manage COVID-19 Related Dry Mouth

If you are experiencing dry mouth symptoms, either alone or along with other COVID-19 signs, here are some methods to help provide relief:

• Drink lots of water and stay hydrated.
• Avoid diuretics like caffeine and alcohol that can dehydrate you further.
• Use over-the-counter saliva substitutes and oral moisturizing gels.
• Chew sugar-free gum or suck on sugar-free hard candies to stimulate saliva flow.
• Breathe through your nose instead of your mouth as much as possible.
• Use a humidifier to add moisture back into the air.
• Rinse your mouth with salt water or baking soda solution to clean your mouth.
• Try zinc lozenges which may boost saliva production.

Make sure to monitor for any oral health changes like gum inflammation, tooth decay, fungal overgrowth, and mouth sores. Contact your dentist if you experience any persistent worrisome symptoms. Also be aware that dry mouth from COVID-19 seems to improve and resolve after recovery from the acute infection.

The Bottom Line

Dry mouth is increasingly recognized as a common symptom of COVID-19, even in mild outpatient disease. SARS-CoV-2 appears capable of infiltrating and replicating within salivary gland tissue, directly impairing normal saliva production. Oral inflammation and ACE2 expression also likely contribute. For some patients, loss of taste is one of the earliest noticeable symptoms and may manifest before any respiratory signs. Dry mouth can not only diminish quality of life, it can lead to secondary oral health complications if severe.

Understanding dry mouth as an early, subtle presenting sign of COVID-19 infection can potentially aid prompt diagnosis and containment of the virus. Rapid isolation and testing of individuals with new onset dry mouth or taste loss, even in the absence of other symptoms, may help break the chain of viral transmission early on. Given the stealthy nature of asymptomatic and presymptomatic spread with COVID-19, identifying these early clinical clues could make a meaningful public health impact going forward.

Disclaimer: This article is for informational purposes only and does not constitute medical advice. Always consult with a healthcare professional before starting any new treatment regimen.