Why do I have red and white spots on my tongue?

White on the tongue usually means something is sitting on top (coating, yeast) or the surface has thickened (keratin, as in leukoplakia). Red means the surface is thin, inflamed or raw, so blood vessels show through. Many conditions produce both at once: a white layer with a raw border, or a red sore with a pale center. The pattern of the two colors is what tells the conditions apart.

Geographic tongue

Smooth red patches where the papillae have temporarily flattened, outlined by slightly raised white or yellow-gray borders. The key sign is movement: the "map" changes over days or weeks. It is harmless and affects a small percentage of people. Our geographic tongue guide covers it fully.

Oral thrush

The NHS describes thrush as white patches in the mouth with a red, sore or itchy mouth; if you wipe the white away, the surface underneath is red and may bleed slightly. It is more common in babies, denture wearers, people using asthma inhalers and after long courses of antibiotics. Thrush needs antifungal treatment. See oral thrush on the tongue.

Canker sores

Round or oval shallow ulcers with a white or yellow base and a red halo. They hurt more than their size suggests and usually heal within one to two weeks.

Lie bumps

Inflamed taste bumps can be red or white, sometimes both side by side, and usually vanish within a couple of days.

Oral lichen planus

An immune condition that causes white lace-like lines, often with red, inflamed or eroded areas between them. On the tongue it can also form white plaques. Cleveland Clinic reports that about 1-4% of people with oral lichen planus develop oral cancer, with higher risk in the erosive (red, sore) form, so it is monitored. See oral lichen planus.

Speckled or non-homogeneous leukoplakia

Leukoplakia is a white patch that cannot be rubbed off. The NHS notes these patches can have red areas. Cleveland Clinic says non-homogeneous (irregular, red-and-white) leukoplakia is about seven times more likely to become cancerous than the flat, uniform white type. This is the single most important reason to get a fixed red-and-white patch checked. See leukoplakia.

Erythroplakia

A red velvety patch, sometimes with white flecks, that does not scrape off. It is considered precancerous and is diagnosed by biopsy.

Two practical tests: does the white come off with gentle wiping, and does the pattern stay in exactly the same place a week later? A patch that does not wipe off and does not move is the one to show a professional.

• Avoid spicy, acidic and very hot food while spots are sore; this helps geographic tongue, canker sores and lichen planus flares alike.
• Use a soft toothbrush and a toothpaste without sodium lauryl sulfate.
• Keep up gentle tongue cleaning on unaffected areas, but do not scrape over red, raw or ulcerated patches, and do not try to scrape off thrush patches.
• If you wear dentures, take them out at night and clean them daily; this is a common factor in thrush.
• If you smoke or chew tobacco, stopping lowers the risk associated with leukoplakia and erythroplakia.

A dentist will look at the pattern, check the cheeks, gums and the rest of the mouth, and ask about medicines, tobacco and alcohol. Thrush is treated with antifungal medicine. Geographic tongue usually needs reassurance only. A fixed white or red patch with no obvious cause is typically biopsied: the NHS describes taking a small piece of the patch to check for abnormal cells. Depending on the result, it may be monitored with regular check-ups or removed.