What is a mouth ulcer, and how is it different from a cold sore?
A mouth ulcer of the common kind – an aphthous ulcer, also called a canker sore – is a small, painful sore in the soft tissues inside the mouth. According to the Mayo Clinic, it can appear on the inside of the cheeks and lips, on top of or under the tongue, at the base of the gums or on the soft palate. It is usually round or oval, with a white or yellow centre and a red border. A tingling or burning feeling may be noticed in the area a day or two before the ulcer appears. Ulcers can appear on their own or several at a time.
A mouth ulcer should not be confused with a cold sore. According to the Mayo Clinic, canker sores do not appear on the outer surface of the lips, are not caused by the herpes virus and are not contagious. The Cleveland Clinic also stresses that, unlike cold sores, which are caused by a virus, they cannot be passed on.
Anyone can get mouth ulcers. According to the Cleveland Clinic, they are most common in teenagers and people in their twenties and are more common in women. In many people they start at a young age and come back over the years; getting a first ulcer after the age of 40 is unusual.
What causes mouth ulcers?
According to the Cleveland Clinic and the Mayo Clinic, the exact cause of aphthous ulcers is unknown. The sources list a number of things that can make ulcers more likely or trigger them:
| Group | Examples |
|---|---|
| Minor injuries inside the mouth | Biting your cheek, a sharp tooth or rough filling, ill-fitting dentures or a brace, brushing too hard, burns from hot food or drink (NHS, Oral Health Foundation) |
| Foods and products | Sensitivity to certain foods (the Mayo Clinic gives chocolate, eggs, nuts, and spicy or acidic foods as examples); toothpastes and mouthwashes containing sodium lauryl sulphate (SLS) (NHS, Mayo Clinic) |
| Changes in the body | Tiredness, stress and anxiety; hormonal changes such as periods or pregnancy; stopping smoking (NHS, Mayo Clinic) |
| Deficiencies and medicines | Iron, zinc, folic acid, vitamin B and vitamin D deficiency; some medicines, such as certain painkillers and beta blockers (NHS) |
| Underlying conditions | Coeliac disease, inflammatory bowel disease such as Crohn’s disease, Behçet’s disease, conditions that weaken the immune system (NHS, Mayo Clinic) |
According to the Oral Health Foundation, the most common cause is minor injury; these ulcers are usually single and heal once the cause is removed. Ulcers that keep coming back in people who are otherwise healthy are called recurrent aphthous stomatitis; the cause is unknown and they are not contagious. The same source also points out that a mouth ulcer can sometimes be the first sign of another illness.
How long do mouth ulcers last, and what types are there?
According to the NHS, mouth ulcers usually heal by themselves within one to two weeks; MouthHealthy, the American Dental Association’s patient website, gives the same time frame. How long healing takes depends on the type of ulcer:
| Type | Features | Healing |
|---|---|---|
| Minor ulcers | The most common type; according to the Cleveland Clinic, usually smaller than 1 cm | According to the Mayo Clinic, usually within 1–2 weeks, without scarring |
| Major ulcers | Larger and deeper, can be very painful; according to the Oral Health Foundation, they can hurt when swallowing and may appear near the tonsils | According to the Mayo Clinic, can take up to six weeks and may leave a scar; the Cleveland Clinic says they can last for months |
| Herpetiform ulcers | Uncommon. According to the Mayo Clinic, 10 to 100 pinhead-sized sores appear in clusters and can merge | Usually 1–2 weeks, mostly without scarring |
According to the Cleveland Clinic, the pain usually eases within a few days.
What can you do at home?
Minor ulcers usually heal without treatment; the aim is to avoid irritating the ulcer and to ease the pain until it heals. The NHS recommends the following:
- Use a toothbrush with soft bristles, and keep up your usual oral care.
- Choose soft foods, and drink cool drinks through a straw.
- Avoid very spicy, salty or acidic food, hard and crunchy food, and very hot or acidic drinks.
- Do not use toothpastes containing sodium lauryl sulphate.
- You can rinse with salt water: dissolve half a teaspoon of salt in a glass of warm water, rinse your mouth and spit it out.
MouthHealthy also notes that hot, spicy and acidic foods can irritate the ulcer. The NHS mentions antimicrobial mouthwashes and pain-relieving gels, sprays or mouthwashes that are available from pharmacies without a prescription; the Cleveland Clinic recommends mouthwashes without alcohol. Ask your pharmacist or doctor which product is suitable for you, and mention any medicines you take regularly. According to the NHS, for severe, persistent or infected ulcers a dentist or doctor may prescribe a steroid spray or tablets, stronger pain-relieving gels or antimicrobial mouthwashes.
What if you keep getting mouth ulcers?
Ulcers that keep coming back may call for a search for the cause. The Cleveland Clinic lists ulcers that come back two or three times a year among the reasons to see a doctor and notes that they can point to an underlying condition. The doctor may order blood tests to check for deficiencies or other conditions.
Identifying your own triggers can also help. The Cleveland Clinic and the Mayo Clinic suggest noticing which foods, products or situations are followed by ulcers and avoiding them, trying a toothpaste without SLS, using a soft toothbrush and managing stress. The Mayo Clinic advises asking a dentist about sharp tooth edges or dental appliances that cause sores. According to the Oral Health Foundation, if the cause is a sharp tooth or a rough filling, a dentist can smooth it, and dentures that rub can be adjusted.
The NHS recommends seeing a GP if you have ulcers in the mouth together with sores elsewhere on the body, for example on the skin or the genitals, or if your joints are painful, red and swollen.
Which mouth ulcers should be seen by a dentist or doctor?
According to the NHS, see a dentist or GP if a mouth ulcer:
- lasts longer than three weeks
- is different from your previous ulcers, for example larger than usual or near the back of your throat
- bleeds, or becomes more painful and red, which may be a sign of infection
The Mayo Clinic and the Cleveland Clinic add the following: ulcers that last longer than two weeks or are larger than 1 cm, ulcers spreading to the outer surface of the lips, pain you cannot manage, ulcers that make eating or drinking difficult, and a high temperature or flu-like symptoms with the ulcer. The time frames given by the sources differ slightly, but the shared message is the same: do not keep waiting for an ulcer to heal if it behaves differently from usual or is not getting better.
Can a mouth ulcer that does not heal be a sign of mouth cancer?
It can, although most mouth ulcers are harmless. According to the NHS, a mouth ulcer that lasts a long time should be checked, because it can sometimes be a sign of mouth cancer. The Oral Health Foundation also asks that any ulcer lasting longer than three weeks be checked.
The NHS lists the following possible symptoms of mouth cancer:
- a mouth ulcer that lasts longer than three weeks
- red or white patches inside the mouth
- a lump in the mouth or on the lip
- pain in the mouth that does not go away
- difficulty swallowing or speaking, or a hoarse voice that does not go away
- a lump in the neck or throat
- unexplained weight loss
According to the NHS, these symptoms are very common and can be caused by other conditions, so having them does not mean you have mouth cancer, but they should still be checked by a doctor or dentist. The risk factors listed by the NHS include smoking and chewing tobacco, drinking a lot of alcohol, leukoplakia (a condition that causes white patches in the mouth), heavy sun exposure affecting the lips and some types of HPV. The Oral Health Foundation states that the risk is much higher when tobacco and alcohol are used together, and adds that regular dental check-ups usually include a check for mouth cancer.
How do we assess mouth ulcers at Rönesans?
At the examination, we ask where the ulcer is, how large it is, how long you have had it and whether you have had similar ulcers before, and we check for anything that could be irritating it, such as a sharp tooth edge, a rough filling, an ill-fitting denture or a part of a brace that is digging in. Prosthetic dentistry (including dentures), orthodontics and endodontics (root canal treatment) are among the areas of treatment at our practice, so if the cause is a tooth, a filling, a denture or a brace, what can be done about it can be discussed at the same appointment. If the ulcer cannot be linked to a cause in the mouth, lasts a long time or comes with other symptoms, further assessment may be needed; in that case, as the sources recommend, you should see your GP or family doctor. The dentist decides how to proceed after the examination.
If treatment is needed, you receive a written treatment and cost plan showing the procedures and the unit and total costs, and you know from the start which dentist will look after you. Costs are confirmed after the examination, based on the treatment plan. Follow-up after treatment runs through a defined process at our practice. Our practice in Serdivan, Sakarya, is open Monday to Friday from 10:00 to 22:00 and on Saturday from 10:00 to 19:00 (Türkiye time). You can communicate with us in English or German; to arrange an appointment, message us on WhatsApp or use our contact page.