Coated tongue: a list of the possible causes


White, yellow, brown: the tongue can be many colours. But if the coating persists, it's time to start searching for clues. Although the causes of a coated tongue vary – and are mostly harmless – in rare cases it can also indicate a serious disease.

White coating on the tongue: where does this come from?

If you haven't eaten for a while, you are likely to get a whitish coating on your tongue. This is caused by food residues remaining on the tongue. It's harmless and easy to remove, either with solid food or by cleaning.

However, the tongue’s rough surface also provides room for all kinds of viruses and bacteria. This means that the coating can also be the symptom of a range of diseases. A strong white coating on the tongue can indicate a stomach flu or cold, inadequate oral hygiene, oral thrush or digestive problems. The coating is a natural condition for people with a fissured (also known as “geographic”) tongue.

It's worth taking a closer look

Diseases like periodontitis, typhus, syphilis, various preliminary stages of cancer or an immune deficiency can also manifest on the tongue. In this respect, the tongue acts as a mirror to our health. Although the causes are usually harmless, it's still worth taking a closer look.

If a disease is the cause, the disease should be treated – and not just the symptoms.

Tongue coating – meaning of the colour

The colour of the coating narrows down the possible causes. Besides white, tongues can also be coated yellow, red, brown, grey or black. Although the causes are usually harmless, it's still worth taking a closer look.

  • Yellow: a yellow tongue is a sign of jaundice or a sick gall bladder or liver. A fungus on the oral mucous membrane can also be yellowish and creates a furry feeling on the tongue.
  • Red: a strongly reddened tongue can be caused by an inflammation of the tongue (glossitis) or a vitamin B12 deficiency. If the tongue surface resembles that of a raspberry, the reason could be scarlet fever or Kawasaki syndrome.
  • Brown: a brown coated tongue can be due to a kidney weakness. Medication, digestive problems, certain foods and zealous use of a mouth rinse also further the condition.
  • Grey: a greyish tongue indicates an iron deficiency or anaemia .
  • Black: a black tongue is usually caused by coffee, tobacco and strongly colouring foods. In rare (and harmless) cases, the reason could be “black hair tongue”. This is when the papillae grow and the tongue looks as though it's covered in hair. Eating causes the papillae to turn black.

Which foods and drinks cause a coated tongue?

Tobacco and coffee have a strong colouring effect. They cause the tongue to turn brown or black, as do balsamic vinegar and soya sauce. Red wine and dark berries like blackberries and wild blueberries, as well as pomegranate seeds, colour the tongue dark red. Beetroot also has a strong colouring effect.

Remove tongue coating with simple household remedies

The most natural way to remove a harmless and slightly whitish coating is to eat solid food. Chewing raw and fibre-rich foods like wholegrain crackers and vegetables will do the trick. The friction on the tongue causes the coating to loosen and disappear. The coating can also be removed with a tongue scraper or by oil pulling. If a disease is the cause, the disease should be treated – and not just the symptoms.

When to see a doctor?

In the case of a permanent conspicuous coating on the tongue, it’s time to see a doctor. A smear test will indicate what the exact cause is. If there are no other visible symptoms, it's better to first see a dentist to rule out any causes originating in the mouth.

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