Mouth ulcers, patches and sore tongue

The mouth changes constantly. Ulcers appear and go, patches come up, the tongue looks different from one week to the next, and almost all of it is harmless and settles on its own. One rule does most of the useful work: anything in the mouth that has not healed within three weeks needs looking at. Not worrying about — looking at.

That rule is worth more than any amount of inspection, because the changes that matter are rarely dramatic and are frequently painless.

It is also worth saying what the mouth does not do. Reading general health off the colour of the tongue — a dark tongue meaning one deficiency, a pale tongue another — has no clinical basis, and the practice sends people looking for the wrong things. What the mouth genuinely shows is more specific, and more useful.

Mouth ulcers

The commonest thing in this article by a wide margin. Recurrent aphthous ulcers come in three forms: minor ones under about ten millimetres, which account for roughly eight cases in ten and heal in a week to ten days without scarring; major ones, larger, more painful, which can last weeks and leave a scar; and herpetiform ulcers, pinhead-sized but appearing twenty or thirty at a time and sometimes merging — which despite the name have nothing to do with herpes.

Common triggers:

• Injury — a toothbrush, a sharp edge on a tooth or filling, a rubbing denture, a bitten cheek. A traumatic ulcer should heal once the cause is dealt with, and one that does not is exactly the situation the three-week rule exists for.
• Stress, and hormonal change, including before a period and around the menopause.
• Toothpaste containing sodium lauryl sulfate, the foaming agent, which some people react to. Switching to a brand without it is a cheap experiment for anyone with frequent ulcers.
• Some foods, commonly chocolate, coffee, tomatoes, citrus fruit, nuts and strongly spiced food.
• Some medicines, including nicorandil, anti-inflammatories such as ibuprofen, and beta blockers.
• Giving up smoking, which commonly provokes a bout and is not a reason to start again.

Frequent or severe ulcers are worth investigating rather than enduring. They can point to low iron, vitamin B12 or folate, and to coeliac disease, Crohn's disease, lupus or Behçet's — so a pattern of them is a reason to see a GP for blood tests as well as a dentist for the mouth.

Most need no treatment beyond time. For the ones that hurt enough to interfere with eating: a benzydamine spray or rinse numbs and soothes and is available over the counter, diluted chlorhexidine mouthwash may shorten them and prevents secondary infection, and a soft or child's toothbrush makes cleaning tolerable. Severe or major ulcers can be treated with a steroid preparation held in the mouth and spat out, which is prescribed rather than bought. Warm salt water rinses are mild, free and genuinely help; salt applied directly to an ulcer does not, and hurts.

White patches

Oral thrush is a fungal overgrowth: creamy white patches that wipe away to leave a red, sometimes sore surface underneath, often with a bad taste or a burning feeling. It is not a hygiene failure. It happens where something has changed the balance — an inhaled steroid for asthma (which is why those inhalers come with advice to rinse the mouth afterwards), a course of antibiotics, dentures, a dry mouth, diabetes, a weakened immune system, or simply infancy. It responds to an antifungal, from a pharmacist or on prescription. Thrush that keeps coming back in an adult with none of the obvious reasons is a prompt to look for the reason rather than to keep treating the symptom.

Frictional keratosis is a white, slightly thickened area where something rubs — a cheek-biting habit, a sharp tooth, a denture edge. The tissue is doing what skin does on a palm. It resolves once the cause is removed, and a patch that persists after the cause has gone is one to have assessed.

Oral lichen planus typically shows as fine white lacy lines, most often on the inside of the cheeks, sometimes with red or ulcerated areas that are sore and make spicy or acidic food difficult. It is an inflammatory condition rather than an infection, it tends to come and go over years, and the sore forms are treated with topical steroids. It is kept under review, because there is a small long-term increase in cancer risk associated with it — small, but the reason the review is offered.

A white patch that cannot be rubbed off and has no explanation is in a different category — leukoplakia — and is assessed rather than watched from home. It is not cancer, but it is recognised as a condition with potential to become so, and the usual course is examination and often a biopsy to find out what is actually there.

Red patches, and the mouth under a denture

A red patch, or a mixed red and white patch, that cannot be explained is the one to take most seriously. Red patches of this kind carry a higher risk of being or becoming something significant than white ones do, and UK referral guidance names them specifically as a reason for a dentist to arrange an urgent check.

Much more commonly, redness under a denture is irritation from the denture itself or thrush growing underneath it — both of which are treatable, and both of which are reasons to have the denture looked at rather than to live with a sore mouth. Cracking and soreness at the corners of the mouth, angular cheilitis, is usually a mixture of infection and something mechanical, such as a denture that has reduced the height of the bite, and sometimes a nutritional deficiency as well.

The tongue

Geographic tongue. Smooth red patches with slightly raised pale borders, in a map-like pattern that changes position over days and weeks. It is harmless, it is not an infection, and it does not need treating. Some people find it stings with acidic, salty or spicy food, which is the only practical consequence.

Black or brown hairy tongue. The small papillae on the tongue's surface become elongated and stained, so the surface looks furred. It is caused by the papillae not being worn down and then picking up colour — smoking, a dry mouth, a soft diet, infrequent tongue cleaning, some mouthwashes and some medicines, including bismuth preparations for indigestion, which turn the tongue black temporarily. It looks alarming and is entirely benign. It reverses with gentle tongue brushing or scraping and dealing with the cause. It is not a sign of infection elsewhere in the body.

A smooth, sore, red tongue, with the usual surface texture lost, is the one genuine case where the tongue reports something systemic: it can accompany iron, vitamin B12 or folate deficiency, and is worth a blood test. That is the grain of truth in the old idea of reading the tongue, and it is narrower and more specific than the idea suggests.

A burning or scalded feeling with nothing visible to see may be burning mouth syndrome. It is more common in women around and after the menopause, and it is real rather than imagined. Deficiencies, a dry mouth, thrush, diabetes and a reaction to a denture material are ruled out first, and where nothing is found it is treated as a nerve-related pain rather than as a mouth problem.

A coated tongue is the commonest cause of bad breath and responds to gentle cleaning. Bad breath that persists despite good cleaning is worth investigating rather than masking — it can indicate gum disease, a dry mouth, or something outside the mouth altogether.

A dry mouth

Saliva does more than most people credit: it washes away sugar and acid, buffers the mouth, carries the minerals that repair enamel, and keeps the soft tissues comfortable. Many common medicines reduce it — some antidepressants, blood pressure drugs, antihistamines, diuretics, strong painkillers — as do some conditions and some cancer treatments.

The consequences are a sharp rise in the risk of decay, more thrush, more soreness, and dentures that stop staying put. It is worth raising with a dentist, because the preventive measures change: high-fluoride toothpaste, more frequent varnish, saliva substitutes, frequent sips of water, sugar-free chewing gum to stimulate what saliva there is, and avoiding the sugary drinks that a dry mouth makes tempting.

Mouth cancer, and what not to wait out

Mouth cancer is uncommon, incidence in the UK has been rising, and the great majority of the changes described above are nothing to do with it. The reason it belongs in this article is that it is highly treatable when found early and considerably less so when found late, and the difference is usually weeks of delay rather than anything medical.

The signs that warrant acting on, where there is no obvious explanation and they have lasted three weeks:

• an ulcer anywhere in the mouth that has not healed
• a red patch, or a mixed red and white patch
• a lump or swelling on the lip or inside the mouth, or a thickening or hardening of the tissue
• a lump in the neck that is there all the time
• pain on swallowing, or persistent pain on one side of the throat
• a hoarse voice that does not clear
• numbness or tingling of the lip or tongue
• unexplained bleeding in the mouth
• a tooth that has become loose with no dental explanation, or dentures that suddenly stop fitting
• difficulty moving the jaw or tongue, or a persistent feeling of something stuck in the throat

Noisy or obstructed breathing is a different matter and needs attention the same day.

One point is worth emphasising because it runs against instinct: early mouth cancer is often painless. A patch or ulcer that does not hurt is not more reassuring than one that does — if anything it is less so, because pain is what usually drives people to get something seen. A painless ulcer that has sat in the same place for a month is precisely the thing to take in.

The main risk factors are tobacco in every form, including chewed and smokeless tobacco; alcohol; and the two together, which multiply each other rather than simply adding up. Betel quid, paan and areca nut carry substantial risk, with or without tobacco added, and are frequently left out of UK material. Human papillomavirus is associated with cancers further back, in the oropharynx. Sun exposure is the main risk for cancer of the lip, which is why lip balm with a sun protection factor is a sensible habit for anyone who works outdoors. A diet low in fruit and vegetables, and a previous mouth cancer, both raise risk. It is more common in men than in women.

But it also occurs in people with none of those risk factors, including lifelong non-smokers who barely drink, and the HPV-associated cancers often turn up in younger people. "I don't smoke" is not a reason to leave something for another month.

Where to take it

A dentist is the right person and usually the quickest route: examining the soft tissues of the mouth is a routine part of a dental check-up, and dentists can arrange an urgent specialist check directly. Where there is no dentist available, a GP can refer. Either way the thing to say is how long it has been there, because that is the detail the referral turns on.

See also cleaning teeth and gums, gum disease and why dental care matters.