You may already know that your fingernails and stool can reveal a lot about how healthy you are. 

But it turns out that some health issues can show up on your tongue, too. Certain conditions can change its colour and even its texture.

According to the health information site Medical News Today: “Changes in tongue colour can indicate an underlying health issue, such as an infection.” 

Sometimes, the signs can point to something serious, they add ― for instance, a blue tongue can reveal very low oxygen.

What does my tongue colour say about my health?

Healthy tongues usually look pink and not too pale, the site says. 

Here’s what other colours may be symptoms of, per Medical News Today:

1) Black

• drinking coffee and tea
• rarely, diabetes or HIV
• bad oral hygiene
• medications, such as some antibiotics
• tobacco use
• radiation therapy

2) White

• oral thrush
• leukoplakia (white patches, often from smoking, that can sometimes develop into cancer)
• lichen planus (a type of rash)

3) Purple

• poor blood circulation and heart issues
• Kawasaki disease (a rare but serious inflammation of blood vessels)

4) Red

• vitamin D deficiency
• scarlet fever
• glossitis (inflammation of the tongue, especially if bumpy
• Kawasaki disease

5) Gray

• geographic tongue (a harmless inflammatory condition)
• eczema

6) Yellow

• bad oral hygiene 
• a dry mouth 
• rarely, diabetes or jaundice 

7) Orange

• bad oral hygiene
• a dry mouth
• some antibiotics

8) Green

• poor oral hygiene 
• oral thrush
• leukoplakia
• lichen planus
• rarely, syphilis
• rarely, oral cancer

9) Blue

• a lack of oxygen from the lungs
• blood disorders
• blood vessel disease
• kidney disease

When should you see a doctor?

Health information site Healthline writes: “As a good rule of thumb, see your doctor if you notice any significant changes in the colour of your tongue, especially if it lasts longer than two weeks.” 

If you notice any significant or sudden changes, see your GP as soon as you can, and if you suspect low oxygen, call 999 or go to A&E. 

That doesn’t just apply to the colour of your tongue either ― any new lumps, patches, or swelling warrant a doctor’s visit.