Dr. Shilpy Bhandari 14 Jul 2022

Mouth ulcers are sores in the oral cavity that develop due to breakage in the soft tissue lining (mucous lining). These sores cause pain in some especially while eating spicy or tangy foods. The prevalence of mouth ulcers is reported to be 4% globally at any point in time. 

Mouth ulcers may result from a wide range of conditions - minor toothbrush trauma, viral infections, nutritional deficiency, systemic disorders, or even mouth cancers. People often tend to ignore recurrent ulcers or treat them with home remedies or over-the-counter medications

In this article, we help you understand the different causes of mouth ulcers and the recommended treatment. 

What are the different causes of mouth ulcers? 

Here are some of the causes of mouth ulcers:

  • Trauma: Trauma or repeated injury to the soft tissue in the mouth due to accidental biting of inner cheeks or tongue, hard toothbrushing, intake of hot foods, poorly fitted dentures, cracked tooth, or impinging braces’ wires may result in ulcers. These are also known as traumatic ulcers which are mostly isolated and rarely multiple in numbers.
  • Medications: Intake of certain drugs that are used to treat cancer, seizures, high blood pressure, overactive thyroid, bone disorders, heart-related disorders, HIV, and hyperactive immune system activity may cause multiple ulcers in the mouth. Besides, commonly used antibiotics or painkillers (non-steroidal anti-inflammatory drugs) can also cause multiple ulcers in the mouth.
  • Radiation injury: Patients undergoing radiation therapy to treat head and neck cancers develop multiple ulcers in the mouth. Radiation causes direct injury to the soft tissue lining, causing ulcers. These ulcers can be painful and cause discomfort while eating, talking, swallowing food, or sometimes while breathing as well. These ulcers resolve after 2-8 weeks, once the treatment stops. 
  • Viral infections: People affected with Herpes virus (e.g., Herpes simplex, Varicella zoster, Epstein-Barr virus, cytomegalovirus) infections, herpangina, hand-foot-and-mouth disease, coxsackievirus, and rubeola develop multiple oral ulcers. These ulcers cause a burning or tingling sensation in the mouth. Viral infections in healthy patients are mostly self-limiting and may resolve in 7-10 days with symptomatic treatment. 
  • Bacterial infections: Bacteria causing gum infections or some sexually transmitted diseases develop multiple ulcers on the gums and oral cavity. 
  • Acute necrotizing ulcerative gingivitis: This condition is mostly seen in people with poor nourishment or a weak immune system. Ulcers are present along the gum margins and interdental papilla (gum tissue between the teeth). The patient may have a fever, malaise, and bad breath.
  • Sexually transmitted disease: Among sexually transmitted diseases, syphilis and gonorrhea reported the presence of multiple oral ulcers. These superficial, scattered, and irregular ulcers with whitish edges are most commonly found in the throat, tongue, inner cheek region, and lips. 
  • Systemic disorders: Several systemic disorders such as cyclic neutropenia, leukemia, HIV infection, pharyngitis and adenitis (PFAPA) syndrome, Behcet's disease, chronic ulcerative stomatitis, autoimmune disorders (e.g., lichen planus, erythema multiforme, pemphigoid), gastrointestinal disorders (e.g., Crohn’s disease), and Oro-facial granulomatosis reported the presence several oral ulcers. 
  • Carcinoma: Any isolated ulcer which enlarges or is present for more than 3 weeks may be associated with cancer. These ulcers are deep-seated and lumpy on the touch. These are mostly seen on the side of the tongue or the area below the tongue (floor of the mouth).
  • Nutritional deficiencies: The deficiency of iron, folic acid, zinc, and vitamin B12 is associated with the development of oral ulcers. 

What are the symptoms of mouth ulcers?

Symptoms of mouth ulcers may vary depending on the cause. However, some of the common symptoms experienced by people include:

  • Presence of one or multiple painful sores on the skin lining (internal) of the mouth.
  • Presence of swollen red skin around the ulcers.
  • Discomfort while chewing food or brushing teeth.
  • Irritation or burning sensation while eating spicy, tangy, or salty foods and liquids.
  • Decreased appetite.

What are the most commonly reported oral ulcers? 

Recurrent apthous stomatitis (RAS), also known as canker sores is believed to affect up to 25% of people worldwide. In this condition, people develop multiple small, ovoid ulcers with yellow or grey surfaces and red margins which recur from time to time. This is reported in children and adults between 10-40 years of age. Women are more commonly affected compared to men. 


The exact cause of RAS is not known. However, several factors that contribute to the condition are:

  • Excess stress and anxiety
  • Biting of lips or inner cheeks
  • Nutritional deficiency especially in iron, folic acid, and vitamin B 12 
  • Cessation of smoking (Trying to quit smoking can be stressful, elevating the stress levels and causing ulcers)
  • Gastrointestinal disorders (e.g., Crohn’s disease, Coeliac disease)
  • Hormonal imbalance during the menstrual cycle
  • Deficiency in the immune system
  • Food allergies 
  • Medications (e.g., painkillers, oral nicotine replacement therapy, and medicines to treat bone disorders)
  • Use of oral healthcare products containing sodium lauryl sulfate 


The 3 different types of Recurrent apthous stomatitis include:

  • Minor apthous ulcers: Minor apthous ulcers are small (<1cm size), round or ovoid ulcers that are formed in groups (1-6 ulcers at a time). They are found on the inner skin of lips, inner cheeks, the floor of the mouth, and the backside of the tongue. These ulcers heal within 7-10 days without forming any scars
  • Major apthous ulcers: Major apthous ulcers are larger (>1cm) and more painful than minor ulcers. These ulcers appear in small groups and heal slowly with scarring over 10-40 days. 
  • Herpetiform ulcers: Herpetiform ulcers are found in older people and mainly in females. They occur when multiple pinpoint ulcers combine and form a large irregularly-shaped ulcer which is highly painful. They are called herpetiform due to their similarity in appearance to the herpes virus. However, these ulcers are not associated with the herpes simplex virus.

How to manage mouth ulcers?

Most mouth ulcers are harmless and resolve within 10-14 days. Some mouth ulcers caused by a virus, bacterial infections, radiation injuries, or some of the variants of apthous ulcers are highly painful. The dentist may recommend the application of topical anesthetic gel, mouth wash, or other supportive therapy to overcome the discomfort. These recommendations help lessen the pain and discomfort. However, they do not fasten the healing process of mouth ulcers. 

Besides, ulcers enlarging in size or that haven’t healed for more than 3 weeks should be suspected for cancer. Such ulcers should be considered for biopsy.

Here are some of the ways to manage mouth ulcers:

  • Avoid the intake of spicy, citrus, crispy, hard foods which can elevate the discomfort.
  • Make use of a straw while having liquids (except hot) to prevent liquid from touching ulcers directly.
  • Use a soft toothbrush and apply mild pressure while brushing your teeth.
  • Take alternative medication on the doctor’s recommendation, if you suspect present medications are causing mouth ulcers.
  • Increase the intake of water. Reduce the intake of fizzy drinks, alcohol, and tobacco.
  • Consult your dentist to round off the sharp edges of dentures.
  • Use over-the-counter medications or apply oral gels (e.g., Orajel or Anbesol) in case of pain.
  • Rinse the mouth with lukewarm salt water 2-3 times a day.
  • Avoid toothpaste that contains sodium lauryl sulfate (if recommended by the dentist).
  • Work on ways to reduce stress and anxiety.
  • Take the supplements (B12, folic acid, or iron) as prescribed to overcome the nutritional deficiencies.

In people with painful, recurring, or prolonged healing ulcers, the dentist may recommend some of the following treatments:

  • Mouth wash: The dentist may prescribe antiseptic chlorhexidine mouthwash to treat mouth sores due to bacterial infections. In people undergoing radiation therapy or the ones with mouth ulcers due to viral infections, mouthwash with Benzydamine (an anti-inflammatory drug) works the best. Mouth rinses with antibiotics, steroids, or morphine (medications to reduce pain) may be recommended for severe mouth sores. 
  • Medications: Medications such as painkillers may be prescribed to reduce the pain. Steroids aid in healing and pain reduction. Medication such as Palifermin aid in the healing of mouth ulcers in people undergoing radiation therapy for head and neck cancer treatment.
  • Low-level laser therapy: Research suggests that using low-level laser therapy may stimulate the healing of mouth sores, reducing the associated pain and discomfort. 
  • Cryotherapy: Cryotherapy can be effective in treating mouth ulcers developed as a side effect of chemotherapy. It involves sucking on ice chips before, during, and after the chemotherapy. Research suggests that ice decreases the blood flow in the tissues and limits the high exposure to the chemicals during the treatment. 
  • Systemic agents: Antiviral, anti-bacterial medications, immunosuppressants, or medications to treat gastrointestinal disorders may be prescribed by the concerned doctors to treat the mouth ulcers that are associated with systemic conditions.
  • Refer to a specialist: People with mouth ulcer diagnosed as oral cancer would be referred to a larger facility and a specialist for the treatment. 

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About the Author:
Dr. Shilpy Bhandari is an experienced dental surgeon, with specialization in periodontics and implantology. She received her graduate and postgraduate education from Rajiv Gandhi University of Health Sciences in India. Besides her private practice, she enjoys writing on medical topics. She is also interested in evidence-based academic writing and has published several articles in international journals.


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