Inflammatory conditions of the mouth

The medical term for inflammation of the cells or tissues lining the inner aspect of the lips, cheeks, gums, tongue and throat is stomatitis. It is also referred to as oral mucositis as it involves inflammation of the mucous membrane lining the mouth.^1,2 It can be acute or chronic (longstanding), mild or serious.² There are various causes ranging from infections, injuries, and allergic reactions to side effects from cancer treatments. Common examples include cold sores from a herpes virus infection and canker sores (aphthous ulcers). Although some causes will heal spontaneously, in other instances it might be necessary to treat the condition with medicines to clear the inflammation. Medicines may also help to relieve the symptoms while the inflammation subsides.^1,2,3,4

Signs and symptoms

Stomatitis may cause any of the following signs and symptoms or a combination thereof:

• Redness and swelling inside the mouth^1,2,3
• Blisters on the lips or inside the mouth^1,2,3
• Sores or ulcers inside the mouth – these are usually white, grey or yellow, with a red border^1,2,3,4
• White or grey patches on the tongue, the roof of the mouth or inside the cheeks¹
• A burning sensation¹
• Pain or discomfort that makes it difficult to eat, swallow, or talk^1,2,3,4
• Peeling²
• Numbness.²

It is also possible to have symptoms of inflammation even though the mouth looks normal.³

Causes and Risk factors

Causes

Acquired lesions inside the mouth may be the result of trauma, infection, cancerous growths, cysts, autoimmune or allergic reactions, blood vessel disease, endocrine disorders, or may be degenerative or nutritional in nature. Sometimes it is not possible to establish a specific cause.⁵ Here is a non-exhaustive list of some of the non-cancerous causes of stomatitis:^1,2,3,4,5

• Infections
  • Viral infections, such as herpes infections that cause cold sores – this is one of the most common causes of stomatitis. Other viral infections include shingles or chickenpox (herpes or varicella zoster), hand-foot-and-mouth syndrome (enterovirus infection), infectious mononucleosis (Epstein-Barr virus) or Koplik spots from measles.
  • Bacterial infections (such as syphilis that may produce a red, painless sore known as a chancre, or gonorrhoea and rarely, tuberculosis).
  • Fungal infections, such as thrush (oral candidiasis) that may develop after a course of antibiotics or corticosteroids and which appear as whitish, cheese-like patches that destroy the top layer of the lining of the mouth when wiped off.
• Aphthous ulceration or canker sores that are painful, sometimes burning, lesions that form on the inside lining of the lips or mouth. They often develop during childhood and is a frequent cause of recurrent ulceration.
• Injuries
  • These may include injuries from ill-fitting dentures, heat damage from smoking, trauma from surgery, or irritation caused by foods and chemicals (found in toothpaste or mouthwash, for instance).
• Allergic reactions
  • These may include allergic reactions to foods or cosmetics (like lipstick).
• Cancer treatments
  • Chemotherapy and radiation therapy can damage healthy cells inside the mouth as these cells are particularly vulnerable to their effects.
• Medicines
  • Examples include medicines to suppress the immune system, beta-blockers and non-steroidal anti-inflammatory medicines.
• Systemic conditions
  • Behçet’s disease – an inflammatory disease affecting many organs, including the eyes, genitals, skin, joints, blood vessels, brain, and gut. It is one of the causes of recurring, painful, mouth ulcers.
  • Stevens-Johnson syndrome – a type of allergic reaction that causes blistering of the skin and sores or ulcers in the mouth.
  • Celiac disease, which is caused by an intolerance to gluten, may also cause mouth ulcers.
  • Inflammatory bowel disease
  • Bullous pemphigoid and pemphigus vulgaris – these are rare autoimmune skin diseases that may cause fluid-filled blisters to form on the skin and in the mouth (and on other mucous membranes throughout the body).
  • Lichen planus, which is an inflammatory condition that affects the lining of the cheeks, tongue, gums, and oesophagus as well as the genitals. It also affects the skin and causes red, swollen tissues with white, lacey patches on mucous membranes. Painful burning sores may develop.
  • Sjögren’s syndrome which is an autoimmune disease that affects the production of saliva (and tears) resulting in dry mouth (and eyes).
• Nutritional deficiencies
  • Examples of such shortages that may result in stomatitis include folate, iron, vitamin B₃ (niacin), vitamin B₆ (pyridoxine), vitamin B₁₂, vitamin C, or zinc deficiency.

Risk factors

The following may increase the risk of developing stomatitis:^1,3,4

• Poor oral hygiene (not regularly brushing your teeth) as this increases the risk of infection
• Dry mouth (from any cause) as too little saliva increases the risk of injury and infection.

Complications

While stomatitis in some instances may be self-limiting (for example a cold sore from a viral infection), the pain and swelling may sometimes be severe enough to hinder eating and drinking. This may lead to dehydration and, if long-standing or recurring, also to malnutrition.^1,2,3

Infections can be both a cause and complication of stomatitis. If the lining of the mouth is damaged because of an injury or medication, it is easier for bacteria or fungi to take hold.¹

Diagnosis

A medical history and physical examination will often provide the diagnosis. It may be easy to recognise the condition, such as a cold sore, by just having a look. Knowledge of medication usage and cancer treatment will provide valuable clues. Other symptoms involving the rest of the body might be indicative of a systemic disease.^1,3 In some instances, special investigations may be required and these may include:^1,2,3

• Swabs for viruses, bacteria, or fungi
• Blood tests to evaluate overall health and to check for signs of systemic diseases
• Allergy tests
• Biopsies, where a small tissue sample is taken and examined under the microscope to check for abnormal cells.

It is important to note that the vast majority of oral mucosal conditions are benign and amenable to surgical, medical or dental treatment.⁵

When to see a doctor

It is not always necessary to consult a doctor when mouth sores or stomatitis first appear. However, the following symptoms may be indicative of an underlying systemic disorder that may require immediate medical attention:³

• Fever
• Blisters on the skin
• Inflammation of the eye
• Any sores in people with a weakened immune system (such as people with HIV-infection or those receiving treatment with medicines that suppress the immune system).

In the absence of the above concerning symptoms, people with a lot of pain, those who feel generally ill, or who have trouble eating should see a doctor within days.³ If an ulcer or sore lasts for 10 days or more, it is also important to consult a doctor or dentist to rule out cancerous or precancerous conditions.^3,5

Treatment

The underlying cause will determine which treatment is most appropriate. Treatment options include, but are not limited to:^1,2,3

• Over-the-counter (OTC) medicines to treat canker sores and cold sores
• Antibiotics, antiviral or antifungal medicines to treat infections or antiseptic mouthwashes
• Vitamins and supplements
• Avoidance of foods or products that triggered the inflammation
• Practicing good oral hygiene
• Protective coatings containing sucralfate and aluminium-magnesium antacids applied as a rinse which may relieve discomfort, but which will not treat the cause
• Topical anti-inflammatories such as mouthwashes or throat sprays containing diclofenac
• Topical or local anaesthetics, like the lidocaine used by dentists to numb the mouth
• Systemic anti-inflammatories, including corticosteroids
• Low-powered laser, which provides immediate pain relief, and which may prevent certain ulcers from recurring.

Topical mouthwashes containing diclofenac are valuable additions to the armamentarium of medicines to treatment painful, inflammatory mouth conditions as these have been shown to provide effective pain relief in patients with aphthous ulceration and in the postoperative period after periodontal (gum) surgery.^6,7,8 Such preparations carry advantages such as no teeth staining, no damage to teeth enamel, no irritation to the oral mucosa, no risk of fungal growth, no drying of salivary glands, and no numbness or stinging sensations.⁶ It has further been shown that diclofenac mouthwash is as effective as oral diclofenac when it comes to pain relief following periodontal surgery, but without the systemic adverse effects.⁷ It may also be beneficial for stomatitis or oral mucositis following chemotherapy or radiation therapy.⁹

Prevention

Although it is not always possible to prevent all causes of stomatitis, one may be able to reduce the risk by:^1,3

• Maintaining good oral hygiene which includes brushing your teeth twice daily, flossing once daily and getting regular dental cleanings
• Eating balanced meals and drinking enough water daily
• Quitting smoking
• Not sharing foods, drinks, or cosmetics (such as lip balm) and avoiding intimate contact (like kissing) with someone with a cold sore.

References

1. Cleveland Clinic; Stomatitis; My.clevelandclinic.org [Internet]; 01 Oct 2024; available from https://my.clevelandclinic.org/health/diseases/stomatitis-oral-mucositis
2. Oakley A; Stomatitis; DermNet [Internet]; 2011; available from https://dermnetnz.org/topics/stomatitis
3. Hennessy BJ; Mouth sores and inflammation; MSD Manual – Consumer Version; msdmanuals.com [Internet]; Apr 2025; available from https://www.msdmanuals.com/home/mouth-and-dental-disorders/symptoms-of-oral-and-dental-disorders/mouth-sores-and-inflammation#Causes_%E2%80%A6
4. Department of Dermatology; Oral Mucosal Diseases; UC Davis Health (Medical School) [Internet]; available from https://health.ucdavis.edu/dermatology/specialties/medical/oral.html
5. Wong T, Yap T, Wiesenfeld D; Common benign and malignant oral mucosal disease; Australian Journal of General Practice; Sep 2020; 49(9) [doi: 10.31128/AJGP-02-20-5250-01]
6. Mainali A, Bajracharya D; Efficacy of 0.074% diclofenac mouthwash in pain management of recurrent aphthous ulcers; Journal of Nepal Dental Association; Jul-Dec 2013; 13(2): 42-45
7. Mishra, A, Amalakara J, Avula H, Reddy K; Effect of diclofenac mouthwash on postoperative pain after periodontal surgery; Journal of Clinical and Diagnostic Research; 2017 Apr; 11(4): ZC24-ZC26
8. Agarwal S, Mathur S, Kothiwale S, Benjamin A; Efficacy and acceptability of 0.074% diclofenac-containing mouthwash after periodontal surgery: a clinical study; Indian Journal or Dental Research; 2010; 21(3): 408-412
9. Brennan PA, Lewthwaite R, Sakthithasan P, McGuigan S, Donnelly O, Alam P, Gomez RS, Fedele S; Diclofenac mouthwash as a potential therapy for reducing pain and discomfort in chemo-radiotherapy-induced oral mucositis; Journal of Oral Pathology & Medicine; 2020; 00:1-4