Black hairy tongue: causes, treatment and when to see a dentist

The Primary Care Dermatology Society (PCDS), which writes guidance for UK primary care, says that no treatment is required for hairy tongue. It adds that gentle daily debridement with a tongue scraper or a soft toothbrush can remove the keratinised tissue. In plain terms, you are brushing off the layer of dead surface cells that has built up on the back of the tongue.

Patient.info, the UK clinician-facing reference, describes the same approach: the condition is treated by improving oral hygiene, brushing the tongue or using a tongue scraper, eating more fruit and roughage in the diet, and using a sodium bicarbonate mouthwash. It names pineapple as a useful food. These are general suggestions rather than a trial-based protocol, so treat them as sensible, low-risk steps.

NHS advice on a white or sore tongue is consistent with this. It says to use a soft toothbrush on your teeth, to brush your tongue or use a scraper, and not to smoke or drink alcohol. It also advises against toothpaste that contains sodium lauryl sulphate and against hot, spicy or acidic food and drink that may irritate the tongue.

A pharmacist can help if you are unsure what is causing the change, whether anything over the counter might help, and whether you should see a dentist or GP.

• Brush your teeth twice a day with a soft toothbrush and a fluoride toothpaste.

• Clean the tongue once or twice a day with a scraper or soft brush, working from the back forwards without scrubbing so hard that it bleeds.

• Cut down on smoking and alcohol, which the NHS lists as things to avoid when the tongue is sore or white.

• Ask your dentist or pharmacist whether any mouthwash or medicine you use could be contributing.

PCDS says hairy tongue occurs most commonly in smokers and in people with poor oral hygiene, and has been associated with the use of certain antibiotics. Patient.info says that if the tongue is furred and brown or black, or appears hairy, particularly towards the back, this is likely to be due to poor oral hygiene, and that at its extreme the condition is called black hairy tongue.

Not every dark tongue is true hairy tongue. The NHS lists a black tongue among the common side effects of Pepto-Bismol (bismuth subsalicylate), a medicine bought from pharmacies and shops for indigestion, heartburn and diarrhoea. The NHS describes this side effect, along with black poo, as harmless and likely to go away on its own. If it bothers you or does not go away, the NHS advises speaking to a pharmacist or doctor.

Other things can make the mouth more prone to a coated tongue. The NHS lists dry mouth, smoking and fasting or crash dieting among the causes of bad breath, and dry mouth itself can be caused by dehydration, medicines, breathing through the mouth at night, anxiety and cancer treatment. If your tongue is coated and you also have a dry mouth, it is worth dealing with both.

The change is usually on the top surface of the tongue, particularly towards the back. The surface looks furry or carpet-like, and the colour can range from white or tan through to brown or black, according to PCDS. The "hairs" are not real hair. They are elongated papillae, the small projections that normally give the tongue its slightly rough texture.

PCDS says most people are asymptomatic. Some notice bad breath or an abnormal taste. The condition is not described as painful. A sore tongue, a burning feeling or bleeding suggests something else is going on, and the NHS advises seeing a GP or dentist if tongue pain or itchiness does not go away or gets worse.

It is a cosmetic and sometimes slightly unpleasant change in the surface of the tongue rather than a disease of the tongue itself. The tongue is covered in tiny papillae. When the surface cells are not shed and cleaned away as they usually would be, keratin accumulates and the papillae lengthen into strands. Debris and bacteria collect between them and stain the surface.

The medical name is lingua villosa nigra. In everyday use, people also call it a hairy tongue, a black tongue or a dark, furry tongue. PCDS includes it in its list of common benign tongue appearances alongside geographic tongue, fissured tongue and atrophic (smooth) glossitis.

None of the UK sources we read gives a fixed timescale, so it would be wrong to promise one. The sources do describe the approach: remove or reduce the things that encourage it, such as smoking, and clean the tongue gently every day. If a tongue is dark because of Pepto-Bismol, the NHS says the effect usually goes away on its own.

If the colour or coating does not improve after you have improved your oral hygiene and stopped any obvious trigger, see a dentist. The NHS makes the same point for bad breath, advising a dental visit if it does not go away after treating it yourself for a few weeks.

The UK sources describe hairy tongue as an accumulation of keratin on the tongue, not as an infection that is passed on. There is no reason to avoid sharing food or kissing because of it. Oral thrush is a different condition that can look like a coated tongue. The NHS says oral thrush in adults is not contagious either.

A coated or discoloured tongue is not always hairy tongue. The NHS says a white tongue can be a sign of a health condition such as anaemia, scarlet fever, lichen planus, leukoplakia, geographic tongue, mouth ulcers or oral thrush, and that you should not self-diagnose. If you are worried, see a GP.

Oral thrush is worth knowing about because it can occur alongside a coated tongue. The NHS describes a red mouth with white patches that leave red spots when wiped off, and says it is more common in people who take antibiotics over a long time, use asthma inhalers, wear dentures, have cancer treatment, or have a long-term condition such as diabetes or HIV.

Hairy tongue is not usually serious, but some features need a proper look. The NHS says to see a GP or dentist if tongue pain or itchiness does not go away or gets worse, or if you have white patches on your tongue. PCDS notes that early mouth cancer may appear as a red or white patch and may be ulcerated, so a patch that does not behave like a coating deserves assessment.

Be especially careful with a single dark patch. PCDS notes that oral melanoma is rare, but its pigmentation varies from dark brown to blue-black. A dark area that stays put, is not on the top of the tongue, is raised, bleeds or is growing should not be assumed to be hairy tongue.

See a GP if you have difficulty or pain swallowing, or if you have a weakened immune system or take immunosuppressant medicines and notice a coating or white patches, since the NHS gives those as reasons to see a GP about oral thrush. Call 111 if you are unsure where to go.

• A dark patch that does not scrape away or change with cleaning.

• Pain, bleeding, a lump or an ulcer on the tongue.

• A white or red patch that does not rub off.

• Tongue symptoms that do not go away or get worse.

• A coated tongue with a weak immune system, or difficulty swallowing.

Most people can start with a pharmacist, who can advise on cleaning, on medicines that might be responsible and on whether to be seen. A dentist is the natural next step for a persistent coating, because they can examine the whole mouth and check teeth and gums, which also affect bad breath. A GP can review medicines and general health, and either can refer on if something looks unusual.

Dental care may be NHS or private depending on where you live and how you register, and charges differ across England, Wales, Scotland and Northern Ireland. Referral for a specialist opinion on a persistent or unusual patch is usually arranged through a dentist or GP. Private dental or oral medicine appointments follow the same clinical approach and, in general, the findings should still be shared with your GP.