Does COVID-19 Cause Mouth Sores?

The SARS-CoV-2 virus causes the highly infectious disease known as COVID-19. This respiratory illness can be transmitted from person to person by respiratory droplets released when an infected person sneezes, talks, or coughs. 

Mouth sores are painful and irritating. They have many potential causes, from oral thrush to herpes; even biting the inside of your cheek can cause a painful sore that lasts for weeks. But can COVID-19 cause mouth sores? Let’s find out. 

How do you catch COVID-19?

You can contract COVID-19 in the following ways:

• Breathing air that contains the SARS-CoV-2 virus when in an enclosed, poorly ventilated space with an infected person

• Touching your eyes, mouth, or nose with unwashed hands after touching an infected surface or object

• Droplets containing the virus landing on your nose, mouth, or eyes

• Shaking hands with someone who has the virus on their hands

The World Health Organization (WHO) recommends keeping a physical distance of at least three feet to avoid infection. 

You should also practice respiratory manners, such as coughing into a flexed elbow (rather than into your hands) and self-isolating when sick or testing positive.

The symptoms of COVID-19

People with COVID-19 can show symptoms ranging from mild to severe. Symptoms may vary according to a person’s vaccination status and with different virus variants.

According to the Centers for Disease Control and Prevention (CDC), common symptoms include:

• Cough

• Fever or chills

• Tiredness

• Runny nose

• Nasal congestion

• Loss of smell or taste

Less common symptoms include:

• Headaches

• Body aches and pain

• Sore throat

• Irritated eyes

• Diarrhea

• Skin rash

• Loss of appetite

• Shortness of breath

• Chest pain

COVID-19 has an incubation period of 2–14 days. You may not have any symptoms during this period, but you can still transmit the virus to other people.

Is a loss of taste and smell a common COVID-19 symptom?

COVID-19 can cause a loss of taste and smell. Patients may report that food tastes metallic and bland. 

Not everyone with COVID-19 experiences this. Early in the pandemic, more than a third of people with COVID-19 reported a loss of smell or taste. However, studies show that recent variants appear less likely to cause these symptoms.¹ ²

Fortunately, most people regain their sense of smell over time, although some still have long-term loss of smell after COVID-19 infection.

What are mouth sores?

A mouth sore is a small open wound that appears on the soft tissues inside the mouth. Mouth sores may appear on the gums, tongue, lips, or the roof or floor of the mouth. Mouth sores can make eating or drinking very uncomfortable.

What are the different types of mouth sores?

There are several types of mouth sores, including the following:

Cold sores

The herpes simplex virus causes these blisters. This virus spreads through sharing utensils or drinking glasses, or by kissing. 

Often, an outbreak starts with a burning sensation in the affected area. Small fluid-filled blisters then appear, and later break open and form small ulcers.

Canker sores

These mouth sores form on the soft, moist lining of the mouth and may appear red, yellow, or white. Unlike cold sores, they are not contagious. 

Scientists do not fully understand the exact cause of canker sores, but they may be related to stress, irritants in foods or oral hygiene products, or minor injuries to the area. 

Canker sores usually go away on their own within 14 days. 

Oral thrush

An overgrowth of yeast causes an oral thrush infection. It causes creamy white areas to develop inside the mouth, which can cause pain or a burning sensation. 

It’s most common in children and people with compromised immune systems.

Gingivostomatitis

A viral or bacterial infection causes this infection, and it’s most common among children. Adults can get it, too, usually due to poor oral hygiene (not brushing and flossing enough). 

Sores or ulcers may appear on the lips, gums, or the inside of the cheeks.

Causes of mouth sores

Mouth sores can have a variety of causes, including:

• Exposure to allergens

• Irritation due to: 

  • A sharp or broken tooth

  • Dentures

  • Orthodontic appliances (like braces)

• Accidentally biting your cheeks or lips

• Irritation from highly acidic or spicy foods or very hot foods or beverages

• Medications, such as certain chemotherapy drugs

• Use of tobacco products

• Viruses, such as the herpes simplex virus (HSV) or hand, foot, and mouth disease

• Overgrowth of yeast

• Autoimmune conditions (such as lichen planus)

• Hormonal imbalances

Symptoms of mouth sores

The symptoms of mouth sores vary depending on their causes. However, mouth sores often cause inflammation, pain, and redness. 

You may also notice symptoms such as: 

• Blistering

• Bleeding

• Burning sensation

• Difficulty eating spicy foods

• Ulceration

Are mouth sores contagious?

Some types of mouth sores are contagious, while others are not. For example, cold sores are caused by the herpes simplex virus, which is highly contagious. 

However, irritation or minor injuries usually cause canker sores, so they’re not contagious. Many other types of mouth sores are also not contagious.

If you aren’t sure what caused your mouth sores, it’s safer to assume you might be contagious. Avoid kissing or sharing utensils or drinking glasses until your sores have healed completely.

The link between mouth sores and COVID-19

People with COVID-19 may develop mouth sores. The most commonly reported type are canker sores. 

They may also develop other types of mouth sores, including: 

• Angular cheilitis (irritation at the corners of the mouth)

• Thrush

• Cold sores

• Swelling of the tongue

• “Geographic tongue” (smooth red patches on the tongue). 

Some studies have also linked the virus to gingivitis and periodontitis (gum inflammation).³

What are the oral complications of COVID-19?

As mentioned in this systematic review, mouth and tongue sores are more common in COVID-19 patients before hospital admission, so these are likely to be related to the viral infection itself.⁴

Oral complications that appear after hospital admission may be related to treatments, medical devices, and impaired immune system function.

Other oral manifestations of COVID-19 include dry mouth and loss of taste or smell.

Is oral thrush a symptom of COVID-19?

Patients with COVID-19 may be at increased risk for thrush, an overgrowth of yeast in the mouth. This may occur because COVID-19 impairs the immune system, which can lead to developing other infections like thrush.

In addition, people with COVID-19 may experience dry mouth, which is a risk factor for oral thrush.

Are mouth sores associated with loss of taste?

A 2020 study found that most COVID-19 patients with mouth sores also reported a loss of taste and smell.⁵

Researchers believe that COVID-19 may directly infect cells in the mouth. This can affect the sense of taste by damaging nerves, and it can also lead to mouth sores.

Are older patients at more risk of oral lesions?

Yes, older adults are more likely to get oral lesions, and the risk increases with age. There are a few different reasons for this.⁶

Older people are more likely to use dentures, which can lead to mouth sores. In addition, dry mouth is more prevalent in older adults. Saliva plays a vital role in maintaining oral health by preventing tooth decay. Without enough saliva, the risk of gum disease, oral thrush, and mouth sores increases. In addition, older people are more likely to have impaired immune systems and chronic illnesses, many of which can lead to mouth sores.

Treatment of COVID-19 cold sores

If you have a COVID-19 infection and are experiencing mouth sores, they’ll typically disappear as your body clears the infection. 

You can manage the discomfort and reduce the risk of further complications with these tips:

Remedies for dry mouth and oral lesions due to COVID-19

You can improve dry mouth symptoms by:

• Limiting caffeine

• Chewing sugar-free gum to stimulate the flow of saliva

• Avoiding tobacco

• Avoiding alcohol-based mouthwashes

• Drinking plenty of water

• Using a humidifier, especially at night

Some lifestyle changes that may be helpful during the healing process include:

• Use a soft toothbrush to avoid causing minor injuries that can trigger a sore.

• Avoid spicy, salty, or hot foods and drinks until the mouth sores have healed.

• Avoid any known allergens or other triggers that cause or worsen mouth sores.

• You can try a mouth rinse for comfort:

  • Dissolve about half a teaspoon of salt in a glass of warm water. 

  • Swish it in your mouth for about 30 seconds, then spit it out. 

  • You can repeat this every few hours as needed.

Medications may be useful in some cases, including:

• Oral gels for pain relief serve as a protective barrier for the sore and address the discomfort. You apply the gel directly to the sore.

• Mouth rinses containing medications to reduce pain and swelling may also be helpful.

• Non-steroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen, may reduce the mouth sore’s swelling and pain.

• Antibacterial mouth rinses may speed the healing of a sore and reduce the risk of an additional infection.

• For oral sores caused by a virus, such as herpes simplex virus, prescription antiviral medications like valaciclovir may be helpful. 

How to treat COVID-related loss of taste and smell

Although there is no guaranteed treatment for loss of smell and taste after contracting COVID-19, some methods may help:

Olfactory training

A therapy known as olfactory training can help people regain their sense of smell after a COVID-19 infection. The treatment involves sniffing various strong smells, such as citrus and cloves. This retrains the nervous system to detect smells and can improve olfactory dysfunction. 

Intranasal medications

Intranasal corticosteroid sprays can treat loss of smell. Studies have found that intranasal steroids don’t offer any additional benefits over olfactory training.⁷

Because steroids can have side effects, olfactory training is usually preferable, but your doctor may recommend them in some cases.

Lifestyle changes

Some people report an altered sense of smell, rather than a loss. This is known as parosmia. It occurs due to changes in the nervous system, which can result in your body interpreting a particular odor differently. 

People with parosmia should eat foods cold or at room temperature and choose bland foods. Meals with complex aromas may exacerbate symptoms of parosmia since the nervous system has a more difficult time interpreting many different scents at once.

How to prevent COVID mouth sores

The only way to prevent COVID-19-related mouth sores is to avoid infection with the SARS-CoV-2 virus. If you become infected with COVID-19, it’s not possible to completely eliminate the risk of mouth sores. 

However, you can reduce your chances of getting a mouth sore:

• Wash your hands with soap and water before handling food or touching your face.

• Stay hydrated by drinking plenty of fluids to prevent dry mouth.

• Use good cleaning procedures before applying creams, gels, or ointments to your face.

If you develop any blisters, don’t pop them. This can lead to an additional infection as a result of the broken skin, and the fluid from the blister may also be infectious to others.

If you develop a mouth sore, avoid touching the area as much as possible. Stay away from close contact with others, including kissing or sharing utensils or drinking glasses, until the sore has healed completely.

When to visit a doctor

Minor mouth sores do not require a doctor. However, visit a healthcare professional if:

• Your mouth sore hasn’t healed after two weeks

• Your symptoms get worse

• You frequently get mouth sores

If you develop severe pain, a fever, or if your mouth sores are so painful that eating and drinking are difficult or impossible, visit your doctor as soon as possible.

The lowdown

COVID-19 is a respiratory infection that can cause dry cough, chills, fatigue, and nasal blockage. It can also cause mouth sores. 

Although the sores may disappear on their own, severe sores may benefit from medical treatment to speed up healing and manage pain. 

Frequently asked questions

What is the most common type of mouth sore?

Overall, the most common types are canker sores and cold sores.

Who can get COVID-19 mouth sores?

COVID-19-related mouth sores can affect anyone. If you have COVID-19, you could get mouth sores.