Is it thrush or just a white tongue?

Mayo Clinic explains that a white tongue usually happens when the papillae swell and trap bacteria, dead cells and debris, and that it is generally harmless and temporary. The usual triggers are everyday ones: not cleaning the tongue, dehydration, mouth breathing, smoking, alcohol, fever and a soft diet. Cleveland Clinic notes it often resolves on its own within a few weeks.

A practical test is gentle cleaning. If a scraper or soft brush lifts the film and the tongue underneath looks and feels normal, an ordinary coating is the likely explanation. For more on that, see why is my tongue white.

Cleveland Clinic describes thrush as creamy white, slightly raised patches, usually on the tongue or inner cheeks, that may also appear on the roof of the mouth, gums, tonsils or throat. The patches can be painful and may bleed a little when scraped. The NHS adds a red mouth, cracks at the corners of the mouth, an altered or unpleasant taste and difficulty eating or drinking.

Thrush usually develops fairly suddenly and does not clear with cleaning, because the yeast is growing in the surface tissue rather than sitting on top of it. Our guide to oral thrush on the tongue covers treatment in more depth.

If you have one of these, lean toward thrush and get it checked:

• A recent or long course of antibiotics
• A steroid inhaler for asthma or COPD
• Dentures, especially if worn overnight
• Diabetes, HIV, chemotherapy or immunosuppressant medicine
• A persistently dry mouth
• Smoking
• Being a baby or an older adult

These risk factors come from the NHS, Cleveland Clinic and DermNet. A healthy adult with none of them and a soft, painless coating is much more likely to have an ordinary white tongue.

Some white areas are neither coating nor thrush. The NHS explains that leukoplakia causes white patches that cannot be rubbed or scraped away, usually painless, and that a patch that does come off may be thrush instead. Oral lichen planus causes lacy white lines, and geographic tongue causes map-like red areas with white borders. Any fixed white patch should be examined by a dentist or doctor.

• Likely coating: drink more water, brush twice a day, clean your tongue gently once a day and review habits such as smoking and mouth breathing.
• Likely thrush: do not scrape it. Speak to a pharmacist about an antifungal treatment, or see a doctor if you have risk factors, pain swallowing, or it does not improve within a week of treatment.
• Patch that will not move: book a dental or medical appointment.

The NHS says oral thrush in adults is not contagious, so there is no need to avoid other people while you sort it out.