We include products we think are useful for our readers. If you buy through links on this page, we may earn a small commission. Here’s our process.

Healthline only shows you brands and products that we stand behind.

Our team thoroughly researches and evaluates the recommendations we make on our site. To establish that the product manufacturers addressed safety and efficacy standards, we:
  • Evaluate ingredients and composition: Do they have the potential to cause harm?
  • Fact-check all health claims: Do they align with the current body of scientific evidence?
  • Assess the brand: Does it operate with integrity and adhere to industry best practices?
We do the research so you can find trusted products for your health and wellness.
Was this helpful?

Mouth sores have many possible causes, such as infections, allergies, trauma, and tobacco use. Seek medical attention for certain mouth sores, including ones that have white patches or that develop after you start a new medication.

In this article, learn about the causes of mouth sores, see some pictures to help you identify them, and get some tips on treating them.

Mouth sores are common ailments that affect many people at some point in their lives.

These sores can appear on any of the soft tissues of your mouth, including the lips, inside of your cheeks, gums, tongue, and floor and roof of your mouth.

Mouth sores, which include canker sores, are usually a minor irritation and last only 1 or 2 weeks. In some cases, they can indicate an infection from a virus, such as herpes simplex, or more severe causes, such as mouth cancer.

Sores in your mouth may be caused by a common or short-lasting condition such as:

Mouth sores may also be caused by a long-lasting condition or a more serious disease, including:

Keep reading to learn about the causes and symptoms of mouth sores — and how to recognize and get rid of them.

Different conditions can cause mouth sores, according to the Merck Manual.

They may look different depending on the cause. Mouth sores can appear a different color than the surrounding tissue, including white, yellow, red, or purple.

The following images show different types of mouth sores. These images are not intended to provide a diagnosis. If you have unexplained mouth sores or mouth sores that come back or last for a long time, it is best to visit a doctor for a diagnosis and treatment.

Warning: Images of mouth sores ahead.

Warning: Images of mouth sores ahead.

Was this helpful?

Canker sores

Canker sores may look like small oval-shaped ulcers in your mouth that appear white, gray, or yellow. They may be surrounded by a red “halo” of irritation. They may also appear as a painful red area.

Canker sore on inner lipShare on Pinterest
A canker sore is a small shallow ulcer on the inside of your mouth. frank600/Getty Images

Canker sores are also called aphthous stomatitis or aphthous ulcers. According to 2021 research, they are common and affect about 20 percent of the general population.

They are usually harmless and heal on their own in a couple of weeks. If you have recurring ulcers, it may be due to other conditions, such as Crohn’s disease, celiac disease, vitamin deficiency, or HIV.

Canker sores may classified by their size. This can include:

  • mild, which are less than 1 centimeter in diameter and heal within 1 to 2 weeks
  • major, which are deeper and larger — 2 to 3 centimeters in diameter — and can take weeks or months to heal
  • herpetiform, which are smaller — 1 to 2 millimeters in diameter — but occur in clusters of 10 to 100 and can take a few weeks to heal

What causes canker sores in your mouth?

Canker sores are commonly caused by trauma like biting the inside of your cheek, burns, allergies, or sensitivities. They may have other causes as well. However, canker sores are not contagious.

Certain conditions may make you more prone to them. These can include:

  • a weakened immune system because of illness or stress
  • hormone changes, such as menstruation
  • a vitamin deficiency, especially of folate and B12
  • intestinal issues, such as Crohn’s disease or irritable bowel syndrome (IBS)
  • exposure to toxins in drinking water
  • emotional or psychological stress
  • smoking or a history of smoking

Cold sores

Cold sores look like fluid-filled blisters that appear near the mouth and lips. They can appear red or darker in color. The affected area may tingle or burn before the sore is visible.

Cold sore on the upper lipShare on Pinterest
Cold sores are tiny blisters that appear on the lip. LPETTET/Getty Images
Photo of cold score on the lip.Share on Pinterest
Photo of cold sore. NHS England

Cold sores are caused by the herpes simplex type 1 virus (HSV-1). Outbreaks may also be accompanied by mild, flu-like symptoms, such as low fever, body aches, and swollen lymph nodes.

This virus can be dormant inside of your body. Sores may appear when the virus reactivates and last for 2 to 6 weeks, according to 2021 research. This can occur when the immune system is weak or during times of stress.

Outbreaks are more common if you:

  • are under stress
  • are ill or have a weakened immune system
  • have had too much sun exposure
  • have a break in the skin of your mouth

The virus that causes cold sores is contagious and can be spread through contact with cold sores. It can be spread through kissing, sharing food, or sharing cosmetics. It is also possible to catch HSV-1 when sores cannot be seen.

Genital herpes, caused by the herpes simplex type 2 virus (HSV-2), can look similar in appearance to cold sores. Both viruses may be spread through sex without a condom or other barrier method if you or your partner has an active outbreak.

Folate deficiency and anemia

A folate deficiency is caused by not having enough folate, also known as vitamin B9. Folate is an important B vitamin used to make and repair DNA. It’s critical to proper development in embryos. Being deficient in folate can also lead to folate deficiency anemia.

Anemia occurs when your supply of red blood cells is too low. When your red blood cells are reduced, damaged, or impaired, you may have problems transporting enough oxygen throughout your body. It can have an impact on different organ systems in your body.

Both folate deficiency and anemia can cause mouth sores. While folate deficiency can cause anemia, other types of anemia, like iron deficiency anemia, can cause mouth sores as well. These sores may look like small mouth ulcers or canker sores and be white, gray, yellow, or red in color.

mouth ulcer from anemiaShare on Pinterest
Anemia can cause mouth ulcers. Tuan_Azizi/Shutterstock
Skin changes on the hands associated with anemiaShare on Pinterest
Anemia can present in many ways, including skin changes. Casa nayafana/Shutterstock

Folate deficiency may also cause additional symptoms, including:

  • fatigue
  • weakness
  • pale skin
  • tongue swelling
  • gray hair
  • growth delay in children

Anemia can also cause additional symptoms that may include:

  • pale, cold skin
  • pale gums
  • dizziness
  • lightheadedness
  • fatigue
  • increased or decreased blood pressure
  • racing or pounding heart

Anemia has many causes and may occur quickly or over a long period of time. Anemia that occurs quickly may be caused by:

  • blood loss from injury
  • surgery
  • endometriosis
  • childbirth
  • heavy menstrual periods
  • gastrointestinal conditions such as ulcers, IBS, and cancer

Chronic anemia may be related to autoimmune diseases, inherited genetic conditions, overexposure to lead, and other conditions.


Gingivostomatitis is a common infection of the mouth and gums, often seen in children.

It produces tender sores on the gums or insides of the cheeks. Like canker sores, they can appear grayish or yellow on the outside and red in the center. Pain can range from mild to severe.

mouth sore from stomatitisShare on Pinterest
Swelling and sores in the mouth is known as gingivostomatitis. James Heilman, MD, CC BY-SA 3.0, via Wikimedia Commons

If you have gingivostomatitis, you may also experience mild, flu-like symptoms. These sores may also lead to drooling and pain with eating. Young children may refuse to eat.

Ulcers caused by this condition can last about 2 to 3 weeks, according to 2021 research.

Gingivostomatitis is often caused by viral infections, such as HSV-1 and coxsackievirus, and bacterial infections, such as Streptococcus. These infections can also be caused by not flossing and brushing teeth regularly.

Infectious mononucleosis

Infectious mononucleosis, also known as mono, can occur with a rash. This rash can occur on the skin or inside of your mouth. Flat spots may appear pink or purple.

Infectious mononucleosis is caused by the Epstein-Barr virus (EBV). It often affects adolescents and young adults in high school and college.

Sore throat with discharge in a person with mononucleosisShare on Pinterest
Infectious mono presents with sore throat with discharge. Another Average Joe/Getty Images

Symptoms typically last for 2 to 4 weeks but may last weeks longer, according to the Centers for Disease Control and Prevention (CDC).

Symptoms may also include:

  • fever
  • swollen lymph glands
  • sore throat
  • headache
  • fatigue
  • night sweats
  • body aches

Oral thrush

Oral thrush is a yeast infection that develops on the inside of your mouth and on your tongue. It’s most common in infants and children, but it may be a sign of a weakened immune system in adults. Having dry mouth or taking medications like antibiotics may increase your risk of developing it.

It looks like creamy white bumps that appear on the tongue, inner cheeks, gums, or tonsils and can be scraped off.

Oral thrush on tongueShare on Pinterest
Oral thrush appears as white fungus on the tongue. Victoria 1/Shutterstock

Oral thrush is caused by an overgrowth of Candida, a type of yeast that naturally occurs in the body. The CDC says this condition is usually treated with antifungal medications for 7 to 14 days.

Additional symptoms may include:

  • pain at the site of the bumps
  • cotton-like feeling in the mouth
  • loss of taste
  • pain while swallowing or eating
  • dry, cracked skin at the corners of the mouth

Hand, foot, and mouth disease

Hand, foot, and mouth disease is caused by viruses in the enterovirus family. It’s common in children under the age of 5.

It causes painful red blisters in the mouth and on the tongue and gums. You may also experience flat or raised red spots located on the palms of the hands, soles of the feet, buttocks, or genital area. On darker skin tones, bumps may appear skin-colored or grayish-brown in color.

Hand, foot, and mouth disease rash on a childShare on Pinterest
Hand, foot, and mouth disease presents as mouth sores with rash on the hands and feet. adriaticfoto/Shutterstock

Other symptoms may include:

  • fever
  • sore throat
  • feeling unwell
  • skin rash

Hand, foot, and mouth disease is contagious but usually not serious. It usually resolves in 7 to 10 days, according to the CDC.

The infection is more contagious during the first week.


Oral leukoplakia is a white patch that develops in the mouth. It is common in people who use tobacco of all kinds.

Leukoplakia may look like thick, white patches on your tongue and the lining of your mouth. They may be raised, hard, or have a “hairy” appearance.

A mouth showing oral leukoplakiaShare on Pinterest
Oral leukoplakia resembles a white patch. Photography courtesy of Michael Gaither/Wikimedia

Leukoplakia can be harmless and often goes away on its own. But 2021 research suggests 1 to 9 percent of people with this condition may develop oral cancer. If you have this condition, visit a doctor, who may take a sample of the cells for diagnosis.

Regular dental appointments may help catch leukoplakia.

Oral lichen planus

Oral lichen planus is a chronic inflammatory disorder that affects the mucous membranes of the gums, lips, cheeks, and tongue.

It may cause white, lacy, raised patches of tissue in the mouth that can resemble spiderwebs. It may also cause tender, swollen patches that are bright red with ulcers. Open ulcers may bleed and cause pain when you eat or brush your teeth. They may also burn or sting.

Lichen planus on tongue.Share on Pinterest
Lichen planus causes a lacy white rash which can present in the mouth. Dermatology11/Getty Images

Lichen planus is not contagious. However, it is a chronic condition that cannot be cured.

Medication, such as corticosteroids and immune response medications, along with using a mild toothpaste may help manage symptoms.

Celiac disease

Celiac disease is an atypical immune system response to gluten that can damage the lining of the small intestine. Damage to the villi — the small hair-like threads in your small intestine — may lead to poor absorption of important dietary nutrients like B vitamins, vitamin D, iron, and calcium.

Vitamin deficiency can lead to conditions like anemia. This may increase your risk of developing mouth ulcers.

Person with Celiac disease gripping stomach in painShare on Pinterest
Celiac disease is caused by a reaction to gluten, which presents with abdominal pain and gastrointestinal symptoms. Vicki Smith/Getty Images

Symptoms range in severity and may differ between adults and children. They can include:

  • diarrhea
  • weight loss
  • stomach pain
  • anemia
  • joint pain
  • bloating
  • gassiness
  • fatty stools
  • skin rash
  • mouth sores

In children, symptoms may include:

  • weight loss
  • growth delay
  • delayed puberty
  • chronic diarrhea or constipation
  • stomach pain
  • yellow or discolored teeth

Celiac disease is a chronic condition and has no cure. You can manage celiac disease through diet and avoiding gluten-containing ingredients such as wheat, barley, rye, and tritical. People with celiac disease may also experience symptoms from cross contamination with these ingredients.

Mouth cancer

Mouth cancer, or oral cancer, is a type of cancer that originates in the mouth or oral cavity. This includes the lips, cheeks, teeth, gums, front two-thirds of the tongue, roof, and floor of the mouth. Cancer is caused by the growth and spread of abnormal cells.

Oral cancer may look like ulcers, white patches, or red patches that appear inside the mouth or on the lips and do not heal. Doctors use the terms leukoplakia and erythroplakia to describe these tissue changes inside the mouth.

Oral cancer in the mouth and gumsShare on Pinterest
Oral cancer can affect the gums. Photography courtesy of Bionerd/wikimedia

Other symptoms of oral cancer may include:

  • weight loss
  • bleeding gums
  • ear pain
  • swollen lymph nodes in the neck

If you have unexplained white patches inside your mouth, visit a doctor. They can perform a biopsy to check for cancerous or precancerous cells. Early detection of cancers such as oral cancer can improve your outlook.

Pemphigus vulgaris

Pemphigus vulgaris is a rare autoimmune disease. Having an autoimmune disease means that your body’s immune system mistakenly attacks healthy tissue in your body. Pemphigus vulgaris affects the skin and mucous membranes of the mouth, throat, nose, eyes, genitals, anus, and lungs.

It can cause painful, itchy skin blisters that break and bleed easily. Blisters in the mouth and throat may cause pain with swallowing and eating.

Pemphigus vulgaris on the skinShare on Pinterest
Skin blisters caused by pemphigus vulgaris. Photography by DermNet New Zealand

Symptoms of pemphigus vulgaris can include:

  • blisters that start in the mouth or on skin
  • blisters that may come and go
  • blisters that ooze, crust, or peel

Treatment usually involves systemic corticosteroids. They typically take effect within 3 months, according to 2021 research.

In most cases, mouth sores cause some redness and pain, especially when eating and drinking. They can also cause a burning or tingling sensation around the sore. Depending on the size, severity, and location of the sores in your mouth, they can make it difficult to eat, drink, swallow, talk, or breathe. The sores may also develop blisters.

Contact a healthcare professional if you experience any of the following symptoms:

  • sores that are larger than 1/2 inch in diameter
  • frequent outbreaks of mouth sores
  • rash
  • joint pain
  • fever
  • diarrhea

Several things can lead to mouth sores, ranging from minor everyday causes to serious illnesses. Usually, a mouth sore might develop if you:

  • bite your tongue, cheek, or lip
  • burn your mouth
  • experience irritation from a sharp object, such as braces, a retainer, or dentures
  • brush your teeth too hard or use a very firm toothbrush
  • use chewing tobacco or smoke cigarettes
  • have the herpes simplex virus

Occasionally, mouth sores are the result of — or a reaction to — the following:

  • over-the-counter or prescription medications, such as antibiotics or corticosteroids
  • gingivostomatitis
  • infectious mononucleosis
  • oral thrush
  • hand, foot, and mouth disease
  • radiation or chemotherapy
  • autoimmune disorders
  • bleeding disorders
  • cancer
  • celiac disease
  • bacterial, viral, or fungal infection
  • a weakened immune system due to AIDS or a recent organ transplant

You can usually tell when you have a mouth sore without needing a healthcare professional’s diagnosis. However, contact a healthcare professional if you:

  • have white patches on your sores, as this may be a sign of leukoplakia or oral lichen planus
  • have or suspect you have herpes simplex or another infection
  • have sores that don’t go away or get worse after a couple of weeks
  • started taking a new medication
  • started cancer treatment
  • recently had transplant surgery

During your visit, a healthcare professional will examine your mouth, tongue, and lips. If they suspect you have cancer, they may perform a biopsy and run some tests.

Minor mouth sores often go away naturally within 1 to 2 weeks. Some simple home remedies might help reduce the pain and possibly speed up the healing process. You may want to:

  • avoid hot, spicy, salty, citrus-based, and high sugar foods
  • avoid tobacco and alcohol
  • gargle with salt water
  • eat ice, ice pops, sherbet, or other cold foods
  • take a pain medication, such as acetaminophen (Tylenol)
  • avoid squeezing or picking at the sores or blisters
  • apply a thin paste of baking soda and water
  • gently dab on a solution that is 1 part hydrogen peroxide and 1 part water
  • ask your pharmacist about other over-the-counter medications, pastes, or mouthwashes that may be helpful

If you see a healthcare professional for your mouth sores, they may prescribe a pain medication, anti-inflammatory drug, or steroid gel. If your mouth sores are a result of a viral, bacterial, or fungal infection, your healthcare professional might provide a medication to treat the infection.

In cases of mouth cancer, a biopsy will be taken first. Afterward, you may need surgery or chemotherapy.

There is no absolute way to prevent all mouth sores. However, you can take certain steps to lower the chance of getting them. These may include:

  • avoiding very hot foods and drinks
  • chewing slowly
  • using a soft toothbrush and practicing regular dental hygiene
  • contacting your dentist if any dental hardware or teeth may be irritating your mouth
  • decreasing stress
  • eating a balanced diet
  • reducing or eliminating food irritants, such as hot, spicy foods
  • taking vitamin supplements, especially B vitamins
  • drinking plenty of water
  • avoiding smoking or using tobacco
  • avoiding or limiting alcohol consumption
  • shading your lips when in the sun, or using SPF 15 lip balm

In most cases, mouth sores have no long-term effects. In some cases, they may leave scarring.

If you have herpes simplex, the sores may reappear. Cold sores may also cause scarring.

In cases of cancer, your long-term side effects and outlook depend on the type, severity, and treatment of your cancer.

What are four types of mouth sores?

Mouth sores can happen for many reasons, including:

  • infections
  • medication use
  • allergies
  • having a weakened immune system
  • cancer

How do you heal sores in your mouth?

A doctor may prescribe medication to address an underlying issue. Some lifestyle tips for treating and preventing mouth sores include:

  • gargling with salt water
  • avoiding smoking and other tobacco use
  • applying a paste of baking soda and water

What viruses can cause mouth sores?

Viruses that can lead to mouth sores include:

  • HSV-1
  • HSV-2
  • HIV and AIDS due to a weakened immune system
  • mononucleosis
  • hand, foot, and mouth disease

When should I be concerned about mouth sores?

It’s best to see a doctor if you have sores that:

  • recur often
  • are large and very painful
  • do not go away or get worse
  • occur with other symptoms, such as a fever

How long do mouth sores last?

This will depend on the cause. Canker sores usually resolve within 1–2 weeks but can take longer. If a sore lasts longer than 2 weeks and does not appear to be healing, it is best to see a doctor.

Mouth sores are common and usually last only 1 or 2 weeks.

They can make eating and drinking painful. Some over-the-counter rinses, gels, or medications may help.

Severe or recurring mouth sores may be a sign of a chronic or more serious condition. If you have frequent unexplained mouth sores or mouth sores that won’t go away, contact a doctor for a diagnosis and treatment