Aphthous ulcers are very common and usually resolve on their own. Which features are normal, which need investigation, and what genuinely eases the pain.
An aphthous ulcer is a small, painful sore in the mouth with a yellowish-white centre and a red rim. Most people experience one at some point. It is usually harmless, but certain features take it out of the ordinary, and that distinction is worth knowing.
What it is, and how it differs from a cold sore
Aphthous ulcers appear on the movable mucosa inside the mouth — the inner cheek, inner lip, under and along the sides of the tongue. They are not contagious and are not caused by a viral infection. They occur singly or in small groups.
A cold sore is caused by the herpes virus, is contagious, and typically begins as small blisters at the border of the lip or on fixed mucosa such as the palate. The distinction changes treatment; antiviral medication has no role in aphthous ulcers.
Why they appear
There is no single cause; several factors usually combine. The commonest trigger is mechanical trauma: biting the cheek, brushing too hard, the sharp edge of a broken tooth, or an ill-fitting denture.
- Stress and irregular sleep
- Deficiency of iron, vitamin B12 and folate
- Phases of the hormonal cycle
- Sodium lauryl sulphate in some toothpastes
- Acidic and spicy foods, and nuts with hard shells
- The first period after stopping smoking
How they normally behave
An ordinary ulcer is no more than a few millimetres across and heals within seven to ten days without scarring. The first three days are the most painful; the pain then subsides quickly.
Recurring a few times a year is also not unusual. Recurrent ulceration reflects an individual predisposition and is not in itself a sign of disease.
When investigation is needed
Certain findings take the picture out of the ordinary and must be assessed. The most important is duration: a sore lasting beyond two weeks with no sign of healing is no longer regarded as a simple aphthous ulcer.
- A sore lasting more than two weeks and not shrinking
- A lesion over a centimetre across, deep, with a firm base
- A sore recurring repeatedly in the same place
- Accompanying fever, weight loss, joint pain or eye symptoms
- Similar sores outside the mouth, on the genitals or skin
- Numerous and continually recurring episodes
Conditions that may underlie them
Where ulcers recur frequently and severely, iron, B12 and folate are checked; correcting a deficiency markedly reduces episodes. Coeliac disease and inflammatory bowel disease can also present in this way.
Where mouth ulcers are accompanied by genital ulceration and eye findings, Behçet's disease comes to mind and further assessment should follow without delay. Medicines that suppress the immune system can also cause similar sores.
What actually eases the pain
There is no treatment that reliably shortens healing; the aim is to reduce pain and make eating easier. Gels containing a local anaesthetic help most when applied just before a meal.
Protective barrier pastes isolate the ulcer from mechanical irritation. In severe cases the dentist may prescribe a topical corticosteroid preparation. Salt water rinses keep the area clean but do not speed healing.
What to avoid
Pressing an aspirin or painkiller tablet directly onto the sore, though a common folk remedy, is wrong; its acidity creates a chemical burn and worsens the picture.
Until healing, avoid acidic fruit juices, heavily spiced food, hard-shelled nuts and very hot drinks. Switching to a toothpaste without sodium lauryl sulphate reduces the frequency of episodes in some patients with recurrent ulcers.
Can recurrence be reduced?
Yes, where a trigger can be identified. When mechanical causes such as a sharp tooth edge or an ill-fitting denture are corrected, recurrences in that area stop. This is the cause most easily found at examination and most easily resolved.
Correcting nutritional deficiencies, settling sleep and managing stress reduce the frequency of episodes. In some people the tendency persists all the same; the aim is then not to prevent episodes but to make them short and less painful.
