Mouth ulcers

Mouth ulcers are open sores on the moist lining inside your mouth. They can occur on the tongue, gums, inner cheeks, inside the lips, or roof of the mouth. Another name for an ulcer is a lesion, meaning an area of damaged tissue.

Many mouth ulcers are minor and heal without leaving a scar. Common canker sores, also called aphthous ulcers, are not contagious. They are different from cold sores, which usually form on or around the lips and are caused by the herpes simplex virus.

An ulcer can also result from injury, infection, medicine, or a health condition affecting another part of the body. Its location, appearance, duration, and accompanying symptoms can help narrow down the cause.

A mouth ulcer may begin with tingling, burning, or tenderness. It often develops into a shallow round or oval sore with a pale, white, yellow, or grey centre and a red border.

Pain can become worse when you eat, drink, brush your teeth, or talk. Spicy, salty, acidic, very hot, or rough foods may sting. A sore on the tongue or near a tooth can also hurt when it rubs against nearby surfaces.

You may have one ulcer or several at once. Some are larger or deeper than typical canker sores and take longer to heal. Depending on the cause, other symptoms may include swollen gums, blisters, fever, a rash, swollen glands, diarrhoea, eye irritation, or sores elsewhere on the body.

Common canker sores are small, painful ulcers that often return from time to time. Their exact cause is not always clear. Episodes may be associated with stress, tiredness, hormonal changes, illness, or minor mouth injuries. They can also run in families.

Minor injury or irritation is another frequent cause. You might bite your cheek or tongue, burn your mouth, or scrape the lining with hard food. A sharp tooth, rough filling, braces, or poorly fitting dentures can repeatedly rub one area.

Food and oral-care products may trigger or aggravate ulcers in some people. Acidic foods can irritate an existing sore. Some people report fewer recurring ulcers after avoiding toothpaste containing sodium lauryl sulfate, a foaming ingredient, although it is not a trigger for everyone.

Less common causes include viral infections, nutritional deficiencies, and reactions to medicines. Low levels of iron, vitamin B12, or folate can be associated with recurring ulcers. Do not stop a prescribed medicine without discussing it with a healthcare professional.

Conditions involving the immune system can occasionally cause repeated or severe ulcers. Examples include coeliac disease, inflammatory bowel disease, and Behçet disease. These usually cause other symptoms as well.

An ulcer that does not heal can rarely be a sign of mouth cancer. Most mouth ulcers are not cancer, but a persistent sore needs examination, especially if there is also a lump, a red or white patch, unexplained bleeding, or difficulty swallowing.

Call emergency services if mouth or throat swelling is making it difficult to breathe, or if you have other signs of a severe allergic reaction.

Seek same-day medical advice if pain or swelling prevents you from drinking, or if you have signs of dehydration such as very dark urine, passing much less urine, marked dizziness, or unusual drowsiness. Prompt advice is also appropriate if you have a weakened immune system and develop spreading mouth sores, fever, or feel significantly unwell.

Book an appointment with a doctor or dentist if:

• An ulcer has lasted longer than three weeks
• Ulcers are unusually large, deep, frequent, or slow to heal
• A sharp tooth, filling, brace, or denture keeps rubbing the area
• You have fever, weight loss, ongoing diarrhoea, eye symptoms, or genital ulcers
• There is a persistent lump, unexplained bleeding, or red or white patch
• Pain makes eating difficult despite self-care

A persistent ulcer may need a prompt specialist assessment. This is a precaution to identify its cause, not a sign that it is necessarily serious.

A doctor or dentist will ask when the ulcer began, whether it returns, and what seems to trigger it. They may ask about medicines, dental appliances, diet, digestive symptoms, skin or genital sores, and recent infections.

They will examine the ulcer and the rest of your mouth. Its location and appearance may suggest trauma, a canker sore, infection, or another cause. Teeth, fillings, dentures, and braces may be checked for rough edges.

Tests are not usually needed for a typical ulcer that is healing. Blood tests may be considered for repeated, severe, or multiple ulcers to look for anaemia, nutritional deficiencies, inflammation, or coeliac disease. A swab may be used if infection is suspected.

A persistent or unusual area may require a biopsy. This means removing a small tissue sample for examination under a microscope.

Most minor ulcers heal on their own. While the area recovers, you can reduce irritation by choosing soft, cool foods and avoiding foods that are spicy, salty, acidic, sharp, or very hot. Drink regularly and use a soft toothbrush.

A gentle salt-water mouth rinse may soothe the area. Spit it out rather than swallowing it. Avoid putting aspirin directly on an ulcer because it can damage the mouth lining.

A pharmacist can suggest suitable pain-relieving gels, protective pastes, mouth rinses, or other non-prescription products. Follow the product directions and check whether it is suitable for your age, health conditions, pregnancy, and other medicines.

For severe or recurring canker sores, a clinician may prescribe a corticosteroid treatment for the mouth. Corticosteroids like prednisone or hydrocortisone reduce inflammation and often work best when started early. Treatment for another cause may include correcting a confirmed nutritional deficiency, adjusting an irritating dental appliance, or managing an underlying condition.

A small canker sore or minor injury often improves within several days and heals within one to two weeks. Larger ulcers may take longer and can sometimes leave a scar.

Ulcers caused by ongoing rubbing may keep returning until the sharp or poorly fitting surface is corrected. Recurrent canker sores can appear in episodes, with symptom-free periods in between.

Arrange follow-up if an ulcer is not clearly healing, returns more often, changes in appearance, or begins to affect eating and drinking. Keeping a brief record of episodes, foods, medicines, and other symptoms may help identify a pattern.

Are mouth ulcers contagious?

Common canker sores and ulcers caused by injury are not contagious. Some infections that cause mouth sores can spread to other people, so avoid sharing utensils or kissing if you also have blisters, fever, or a suspected infection.

Is a mouth ulcer the same as a cold sore?

No. Canker sores usually occur inside the mouth and are not caused by the cold-sore virus. Cold sores commonly form as grouped blisters on or near the lips, although herpes infections can sometimes affect the inside of the mouth.

Should I pop or scrape an ulcer?

No. An ulcer is not a fluid-filled spot that needs draining. Picking or scraping it can increase pain, delay healing, and introduce infection.

Can stress cause mouth ulcers?

Stress may be linked with episodes of recurrent canker sores, but it is rarely the only possible factor. Consider medical or dental advice if ulcers are persistent, severe, or accompanied by other symptoms.