What Are Mouth Sores? – How do Mouth Sores develop?

Mouth sores are considered as one of the common oral conditions that affect one or people at least once in their life. Typically, mouth sores are characterized as ulcerative lesions that form on the soft tissues of the mouth. The most common areas in the mouth involve the gums, tongue, roof of the mouth and floor of the mouth, lips and inner cheeks.

Additionally, some different areas that may support the development of mouth sores include the lining of the esophagus and throat. Many dental conditions like gingivostomatitis, oral infections, cancerous lesions in the mouth, cold sore, and nutritional deficiencies are associated with the occurrence of mouth sores.


Several potential factors may cause this painful oral condition. The treatment depends on the type of cause. However, the symptomatic approach is the first line of treatment. Let’s read further to know more about the development of this unique oral condition.

What are mouth sores?

Mouth sores are characterized as small painful ulcerative lesions that develop on the oral tissues. The common sites of mouth sores formation include the tongue, lips, inner cheeks, palate, and the gums. Most of the mouth sores are self-healing and heal in a span of 7-14 days. However, some may be contagious and may require prompt treatment. (1) Typically, mouth sores can be characterized in to two types –

Canker sore

Canker sores are usually characterized by the formation of shallow, white to yellow lesions that are often surrounded by a red, inflamed border. Canker sores are generally non-contagious. These lesions are painful and tender even to touch. The most common sites for sore canker formation include the tongue, inner cheek, throat, lips, and gums.

Cold sore

Cold sores, on the other hand, form in clusters. These are characterized as fluid filled blisters commonly found on the lip or the skin surrounding the lips. Moreover, cold sores can breakout to form oozing, crusty ulcerative lesions. Cold sores may also develop under the nose or chin. Unlike canker sores, cold sores are highly contagious and often transmit the herpes simplex infection. The treatment for cold sore mainly includes anti-retroviral medication.

What are the different causes of mouth sores?

There is a wide range of potential causes that may lead to the formation of mouth sore. Some of the minor factors may include the following –

  • Cut on the tongue, inner cheek or lip
  • Burning mouth syndrome
  • Traumatic injury to the oral tissues from a sharp object like orthodontic wire, retainer or dentures
  • Improper brushing habits that include brushing too hard with the toothbrush
  • A practice of smoking tobacco
  • Incidence of herpes simplex infection

A deficiency in the health system or immunity of the body can also form the mouth sores. Some of these conditions include –

  • The weak immune system caused by stress and illness
  • Hormonal changes
  • Vitamin deficiency foe example deficiency of vitamin B12 and folate (2)
  • Presence of Crohn’s disease or irritable bowel movements

Other potential causes of mouth sores may include –

  • Medication like sulfa drugs, phenytoin, and other over-the-counter drugs
  • Impetigo may cause oozing, honey colored, crusted extremely painful mouth sores.
  • Mouth piercings in the tongue, lip or cheeks
  • Chickenpox
  • Poorly fitted dentures
  • Excessive stress
  • Bleeding disorders
  • Autoimmune diseases
  • Bacterial, viral or fungal infections
  • Excessive radiotherapy and chemotherapy

What are the characteristic signs and symptoms of mouth sores?

Mouth sores are typically characterized as fluid filled blisters or ulcerative lesions in the mouth. The severity of the symptoms depends upon the size and location of the mouth sore. Some of the characteristic features of mouth sores are listed below.

Immediate signs and symptoms

Some of the immediate signs and symptoms of mouth sores include –

  • Pain and discomfort
  • Difficulty in eating, drinking and chewing
  • Difficulty in swallowing and breathing
  • Associated burning sensation of the mouth (3)
  • Tingling sensation around the lesion
  • Blister formation
  • Red sores that may vary in size – small to more substantial than half an inch
  • Frequent outbreaks of fluid filled blisters
  • Rash
  • Joint pain
  • Flu-like symptoms that may include fever, diarrhea, and nausea

Long term effects of mouth sores

Most cases of mouth sores do not have any long-term effects. However, as the severity of the condition increases, mouth sores may present with the following long-term effects –

  • Mouth sores may reappear in case of herpes simplex infection or aphthous stomatitis.
  • Often the mouth sores or blisters may break and leave a permanent scar on the tissue.
  • Common reasons for the outbreak of mouth sores include stress, weak immune system, sun exposure, and break in the skin or mucosal layer of the mouth.
  • Cancerous lesions may have a different set of long-term symptoms depending on the type, severity, and treatment of the condition.

What dental diseases are associated with the formation of mouth sores?

Some of the potential oral diseases that may be associated with the formation of mouth sores include the following –

  • Cold sore – the formation of a cold sore is characterized by the presence of fluid filled blister near the mouth and lips. Often the lesion is painful and is associated with a tingling or burning sensation that initiates as the mouth sore develops on the oral tissue. Most of the time, the cold sore outbreaks accompanied by flu-like symptoms that include fever, aches, and swollen lymph nodes. (4)
  • Gingivostomatitis – also known as gingival enlargement, this condition is characterized by tender and sore gums associated with yellow or grayish canker sore formation on the surface of the gums and inner cheeks. The ulcerative lesions often have a red center. Gingivostomatitis is commonly seen in children and causes flu-like symptoms associated with excessive drooling and pain.
  • Anemia – Anemia is a common health condition wherein the red blood cells significantly get reduced, impaired, or damaged. Moreover, there is a decrease in the oxygen-carrying capacity of the blood. Some of the typical symptoms of anemia include pale, cold skin and gums, the formation of mouth sores at the corner of the mouth, dizziness, and fatigue.
  • Canker sore – canker sores are typically called as aphthous stomatitis or ulcers. These develop as small painful clusters of oval-shaped ulcerations on the oral tissues. Often these lesions may appear as red, white or yellow in color. Canker sores are self-healing lesions and usually indicate a sign of nutritional deficiency or infectious health disease. (5)
  • Oral cancerous lesions – most of the oral cancerous lesions develop as mouth sores in the beginning stages and turn into vicious malignant ulcers. Some of the common cancerous lesions associated with mouth sores include leukoplakia, lichen planus, pemphigus, and mouth cancer.
  • Infectious conditions – most of the infectious conditions that may be associated with the formation of mouth sores include oral thrush, hand foot, and mouth disease, and herpangina. Each lesion has a characteristic set of signs and symptoms. However, the formation of red spots or ulcers int the mouth is a common clinical feature.
  • Celiac disease – celiac disease is an immune deficiency that damages the lining of the small intestine in response to gluten. Such damage to the small intestine causes a lack in the absorption of essential vitamins, calcium, and iron. Celiac disease can affect both the adults and children. Some of the common symptoms include – stomach pain, weight loss, pain in the joints, mouth sores, and skin rash formation. (6)

How are mouth sores diagnosed?

Typical diagnosis of the mouth sores includes a thorough medical and dental history of the patient, followed by a complete oral examination. The oral examination may consist of –

  • Presence of white patches that may indicate the formation of cancerous lesions like leukoplakia and lichen planus.
  • Signs of typical oral infections like herpes simplex and aphthous stomatitis. (7)
  • Persistence of the mouth sores
  • Drug related ulcerative lesions
  • Mouth sores that may have developed as a sign of on-going cancer treatment

Often physical oral examination can help to determine the potential underlying cause of the mouth sore. However, some conditions like nutritional deficiency, oral cancer, and infectious lesions may require significant tests that may include blood tests and biopsy reports.

What is the treatment for mouth sores?

Mouth sores are typically self-healing lesions that disappear in a span of 10-14 days. However, some injuries may persist for a period of six months. Treatment of mouth sores usually involves home remedies that symptomatically heal the lesion. Some of the effective home-based treatment for mouth sores include –

  • Preventive methods to avoid spicy, hot and acidic food or drinks
  • Avoid tobacco smoking and alcohol consumption as it may aggravate the mouth sore
  • Warm salt water gargles always provide a soothing effect in the mouth
  • Suck on ice pops or drink cold water and cold non-fizzy drinks (8)
  • Painful mouth sores can often be treated with medications like acetaminophen or Tylenol
  • Never disturb the mouth sore by touching, pinching or squeezing the blister
  • Ulcers can be cleaned by using a thin paste of baking soda and water. However, over-the-counter pastes or mouth wash can also work efficiently.
  • In severe conditions of mouth sores, consult a doctor. Often the medical therapy includes a course of anti-inflammatory and steroid medications. Cause definitive treatment may be approached after proper diagnosis of the condition.
  • Cancerous lesions may require a biopsy confirmation followed by an extensive chemotherapy an surgical procedure.

How to prevent mouth sores?

Prevention of mouth sores does not have a definitive method or line of precautionary measures. However, there are some preventive steps that you can follow to avoid the occurrence of this painful oral condition –

  • Maintain a healthy well-balanced diet that mostly consists of alkaline food items.
  • Avoid spicy, acidic, and very hot food or drinks that may irritate the soft tissues.
  • Maintain proper oral hygiene by gently brushing the teeth daily.
  • Follow stress reduction and relaxation therapies to reduce the formation of stress ulcers.
  • Always ensure proper nutritional supply. Take vitamin supplements if required especially B vitamins. (9)
  • Keep yourself hydrated by drinking plenty of water regularly.
  • Quit the habit of smoking tobacco or drinking alcohol.
  • Always take proper skin care measures; for example, use sunscreen and sun-protective lip balm to minimize sun exposure to the skin.

An overview of mouth sores

Mouth sores are a painful and irritating oral condition. This condition often makes eating and speaking difficult. Some of the potential causes of mouth sores include infectious lesions like herpangina, hand foot mouth disease, medications, inflammation of the oral tissues, traumatic injury to the mouth and formation of cancerous lesions.


In most of the cases, mouth sores heal on its own with the help of symptomatic treatment. However, severe cases may require proper diagnosis and treatment planning. The procedure often depends on the type of cause. Typical symptoms of mouth sores include pain and discomfort, bleeding from the lesion, and inflammation of the surrounding area. Mouth sores can also have long term effects on the functioning of the mouth.

It is essential to consult the dentist immediately as you notice any changes in the oral tissues. Early diagnosis always brings in a better prognosis.


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