What is it?
Black hairy tongue develops when the thread-like papillae on the top of the tongue are not shed as they normally would be and grow longer instead. The lengthened papillae give a hair-like look; food debris, bacteria and pigments collect between them. The colour is not always black: it can also be brown, yellowish, greenish or grey.
Alarming as the appearance is, the change is only on the surface. There is no hair on the tongue and no hair is growing; what you see is lengthened papillae. Most people have no pain. Some describe a metallic taste, bad breath, a feeling of thickness on the top of the tongue, or gagging when it touches the palate.
The change starts in the back and middle part of the tongue and does not usually spread towards the tip. It is not an infection, it does not pass from person to person and it has not been linked to cancer. Once the triggers have gone and mechanical cleaning becomes regular, the appearance is expected to settle.
Signs
You will not necessarily have all of these at once.
Why does it happen?
- 01
Papillae that are not shed
The surface of the tongue is normally worn down all the time by chewing and cleaning. In people who eat soft food, who chew less or who never clean their tongue, this natural wear is reduced and the papillae grow longer.
- 02
Habits that leave colour behind
Cigarettes and other tobacco products, strong tea and coffee cling easily to the lengthened papillae. They are not the only cause of the condition, but they decide how dark the appearance becomes.
- 03
Dry mouth and certain medicines
When there is less saliva, the surface cannot clean itself. This appearance has been reported more often after a course of antibiotics and in people taking bismuth-containing stomach medicines.
- 04
Mouthwashes and a lapse in mouth care
Oxidising mouthwashes, or antiseptic mouthwashes used continuously for a long time, can change the balance of bacteria in the mouth and the colour of the surface. Brushing less often speeds the picture up.
How does it progress?
- Colour change
A change of colour on the surface
The middle and back of the top of the tongue darkens. The papillae have not yet lengthened noticeably; this stage often goes unnoticed.
- Lengthening
Papillae lengthen and the hair-like look appears
The papillae grow long enough to be seen with the naked eye, the build-up between them increases and the appearance becomes obvious. People usually come to the clinic at this stage.
- Symptoms
Taste and odour symptoms are added
A metallic or unpleasant taste, bad breath and the feeling of the tongue touching the palate can appear. What produces the symptoms is not the colour but the layer of bacteria collecting between the papillae.
- Settling
Improvement with cleaning
With regular mechanical cleaning and fewer triggers, the papillae start to shed and the colour lightens. This change is normally measured in weeks rather than days.
How is it treated?
The diagnosis is made from the appearance; further tests are usually not needed. The dentist first tells this picture apart from the ones that look like it: a white layer that can be wiped off points to thrush, while a dark patch that stays fixed in one spot calls for a separate assessment. You will also be asked about the medicines and mouthwashes you use.
Mechanical cleaning, not medicine, is at the centre of treatment. The top of the tongue is cleaned twice a day with a soft brush or a tongue cleaner, from back to front and without pressing; the mouth is then rinsed with plenty of water. A slight gag in the first few days is normal, and sticking the tip of the tongue out reduces it.
Alongside this, the triggers need to be reviewed: cutting down on or stopping smoking, limiting dark drinks, drinking more water, and talking to your dentist about mouthwashes you have been using for a long time. Do not stop any medicine on your own; if a change is needed, plan it with the doctor who prescribed it.
- The dark patch stays in one spot and does not lighten with cleaning
- There is a painful sore that does not heal, or a hardened area, on your tongue
- The change of colour comes with difficulty swallowing or with bleeding
How is it prevented?
- Clean your tongue every day; regular mechanical cleaning is the most effective measure in this condition.
- Stay away from tobacco products; rinse your mouth with water after strong tea and coffee.
- Do not keep using antiseptic mouthwashes for weeks on end without advice from your dentist.
- If your mouth is dry, have the reason looked into; if the dryness is not dealt with, the appearance is expected to come back.
Frequently asked questions
- Is this a fungal infection?
- No. In thrush the white layer comes away when wiped with gauze, leaving a red surface underneath; in black hairy tongue the lengthened papillae do not wipe off. The two can also occur together, which is why the distinction has to be made at an examination. Antifungal medicines on their own do not change this appearance.
- How long does it take to clear?
- No exact time can be given. When cleaning is kept up regularly and the triggers are reduced, the appearance is expected to lighten over weeks. If cleaning slips or smoking continues, the picture commonly comes back; that does not mean the treatment has not worked.
- Can toothpaste or mouthwash change the colour?
- Some antiseptic and oxidising mouthwashes can contribute to staining of the tongue and the teeth when used for a long time. If you use such a product, tell your dentist; it is sensible to review together how long you need to keep using it.
This content is for general information and does not replace an in-person examination. Symptoms overlap between conditions, and a diagnosis can only be made clinically.