When you can hardly eat or speak

What are canker sores?

Canker sores (aphthous ulcers) are small inflammatory lesions of the oral mucosa, usually round or oval in shape. They typically show a pale, often whitish area in the centre, surrounded by a reddened border. These painful spots most commonly occur on the soft tissues inside the mouth, for example on the inner cheek, the lips, the tongue, the palate or the gums.

Although they are usually harmless and tend to heal on their own without specific treatment, many people find them very bothersome, especially when speaking, chewing or swallowing. The size of canker sores can vary widely: some are only a few millimetres, while others can reach several centimetres.

Canker sores are among the most common changes of the oral mucosa and can occur singly or in multiples. Recurrences are also possible – this is then referred to as a chronic form. Because persistent or particularly severe canker sores can sometimes be a sign of more serious health issues, medical advice should be sought for unclear or long-lasting symptoms.

What forms of canker sores are there?

Canker sores can appear in different forms that vary in extent, number and course. Basically, three main types are distinguished. The most common is the so-called minor form. These are small, superficial mucosal lesions that usually occur in small numbers. This form is considered relatively harmless and generally resolves within a few days up to about two weeks.

Less common, but more pronounced, are the so-called major canker sores. They reach a larger size and are associated with more intense pain. Because they penetrate deeper into the tissue, the healing process often takes several weeks and may result in scarring. Another, rather rare, form is the herpetiform appearance. It is characterised by numerous very small lesions that can occur in clusters across the entire oral mucosa. Despite their small size, they often cause significant problems because they lie close together and occasionally merge.

There are also people who experience recurrent canker sores. Specialists describe this form as chronic-recurrent. It occurs particularly often in younger people and in women. With increasing age, the tendency to develop such lesions often decreases.

What are the symptoms of canker sores in the mouth?

The first signs of a canker sore are often abnormal sensations such as an unpleasant tingling or burning, already noticeable before a visible change of the mucosa appears. Many sufferers also report a tense feeling of pressure at the affected site.

As the condition progresses, pronounced pain often develops, which increases on touch or mechanical stress. Eating acidic or strongly seasoned foods can intensify the pain, as can movements involved in speaking or chewing. In severe cases – for example with large or deep mucosal lesions – general well-being can also be affected. In such situations some patients report fever, swollen lymph nodes or a general feeling of illness. Rarely, marked lesions may leave scarring after healing.

The number and arrangement of canker sores can also provide clues about their type. While some forms occur singly, others – such as the herpetiform variant – show many pinhead-sized lesions at the same time. These may look similar to a herpes infection, but are not virologically related. In recurrent canker sores, patients often describe a repeatedly similar course with comparable pain patterns and typical locations.

What causes canker sores in the mouth?

The exact triggers of canker sores are not yet fully understood. However, there are several factors that can favour their development. In many sufferers, a genetic component appears to play a role; that is, if close relatives are affected, the risk of developing them oneself is increased.

Moreover, the reaction of the oral mucosa to external irritants seems important. Small injuries in the mouth, for example from bites, poorly fitting dentures, hard toothbrushes or invasive dental treatments, can contribute to the formation of these painful lesions. Hormonal changes, such as those occurring during pregnancy, are also suspected of increasing the risk.

An insufficient supply of certain nutrients – especially iron, zinc, folic acid and vitamin B12 – can make the mucosa more susceptible. Such deficiencies often occur in the context of anaemia. Individual intolerances or reactions to certain foods, such as chocolate, coffee or highly spiced dishes, can also play a role.

Another possible influence is the body's immune system: if it is weakened – for example due to chronic illnesses or high levels of stress – the mucosa is less able to defend itself against irritation. Mental stress is also considered an aggravating factor, as psychological stress can impair the immune system and reduce the mucosa's ability to regenerate.

Some experts also suspect that certain ingredients, such as sodium lauryl sulfate in toothpastes, may slow healing or increase an existing sensitivity. Finally, there is evidence that chronic inflammatory conditions such as Crohn's disease or ulcerative colitis, as well as rare vascular disorders like Behçet's disease, can cause similar changes in the oral mucosa.

Are canker sores contagious?

Canker sores are not caused by contagious pathogens such as viruses or bacteria and are therefore not transmissible. There is no risk of contagion through direct contact, sharing cutlery or kissing. Even though they appear inflammatory, they are strictly localised and do not pose an infection risk to others. Even when they recur, the risk to people around the sufferer is excluded. Canker sores develop independently of infection and usually arise spontaneously in individual persons.

Should you see a doctor for canker sores?

A medical consultation is usually not necessary for canker sores because they are mostly harmless and heal on their own after a short time. However, there are situations where medical assessment is advisable. If the mucosal lesions occur particularly frequently or recur at increasingly shorter intervals, it should be checked whether an underlying disease is present.

The same applies to very large or numerous canker sores, as can be seen in certain special forms. A medical check-up is also recommended here to avoid possible complications. In addition, you should seek medical advice if general symptoms such as fever or persistent exhaustion occur, or if the mucosal lesions do not improve after several weeks.

Can you prevent canker sores?

Yes, there are several ways to reduce the risk of developing canker sores. First and foremost, irritating or injurious influences on the oral mucosa should be avoided as far as possible. For example, it can help to use a soft-bristled toothbrush and to pay attention to a gentle tooth-cleaning technique. The choice of toothpaste is also important: products without foaming agents such as sodium lauryl sulfate are generally better tolerated by sensitive individuals.

Diet can also play an important role. A varied and nutrient-rich diet supplies the body with important vitamins and trace elements, particularly folic acid, iron and vitamin B12. A deficiency in these nutrients is associated with an increased tendency to develop canker sores. Those who consciously avoid certain foods should ensure that potential nutritional gaps are compensated for.

In cases of recurrence it is worth observing possible individual triggers. Some people react sensitively to certain foods such as nuts, citrus fruits or very spicy dishes. Mechanical irritations, such as an ill-fitting orthodontic appliance or biting the inside of the cheek, can also play a role. In such situations, adjustments or dental advice may be helpful.

What you can do for canker sores: useful tips

• Avoid foods that further irritate the inflamed mucosa. These include crunchy or hard foods, acidic, salty and spicy dishes, carbonated drinks and alcohol. You can eat pureed food and soups to spare your oral mucosa. Cold foods are generally perceived as soothing.
• Maintain good oral hygiene, otherwise unhealthy bacteria can spread in the irritated mouth. Brush your teeth thoroughly with a soft toothbrush and do not forget to clean the interdental spaces with dental floss. Note that alcohol-based mouthwashes and toothpastes containing sodium lauryl sulfate can worsen symptoms.
• Use antiseptic mouthwashes containing chlorhexidine or triclosan. These will not speed up healing but can reduce the proliferation of harmful germs when a mucosal lesion is present.
• Tinctures based on myrrh or rhubarb root have a mild vasoconstrictive effect on the oral mucosa and help relieve pain.
• Squeeze a damp tea bag lightly, place it in the fridge for 20 minutes, press the tea bag onto the affected area and leave it for 15 to 20 minutes. Repeat this two to three times daily until the pain subsides. The tannins abundant in green and black tea have analgesic and anti-inflammatory effects. 
• Mix one teaspoon of honey with a quarter teaspoon of turmeric powder, apply the paste to the affected area and leave it for 15 to 20 minutes. Repeat this two to three times daily until the canker sores disappear. Honey and turmeric have antiseptic and anti-inflammatory properties.
• Rinse the mouth four to five times a day with a baking soda mixture. Use one teaspoon of baking soda for a glass of warm water. This mouth rinse helps restore the pH in the mouth.
• Another effective mouthwash can be prepared from five to seven drops of tea tree oil in a glass of water. Rinse your mouth with it three times a day to help prevent further canker sores. Tea tree oil is a strong antiseptic. 
• Aloe vera is known for its anti-inflammatory effect and can speed up the healing process. Extract the juice from an aloe vera leaf, apply it to the canker sores and leave it on for 30 minutes. Repeat this three or four times a day. 
• Hold a small ice cube directly over the wound and let it melt slowly to reduce pain and irritation. 
• For aphthous stomatitis or stomatitis, apply pain-relieving gels containing appropriate active ingredients directly to the blisters on the inside of the cheeks.
• If canker sores are very severe or recur frequently, medical advice is recommended. See a doctor also if canker sores lead to bacterial infections. 
• The best protection against inflammations, including in the oral mucosa, is an intact immune system. Eat healthily, get enough sleep, relax regularly and stay physically active to help prevent canker sores. 

Canker sores are usually harmless, but their symptoms can be very painful. Therefore it is important to act early and avoid irritants.