Why is my tongue gray?

Look closely, ideally in daylight. A gray coating sits on top of the tongue, is usually thickest toward the back, and partly lifts when you scrape or brush. A gray color change is in the tissue itself, looks the same after cleaning, and often shows in the lips and gums as well. The first is common and usually minor; the second needs more attention.

Being unwell

A fever, sore throat, cold or stomach bug means you eat less, drink less and often breathe through your mouth. Saliva stops rinsing the tongue properly and a thick coating forms. The MSD Manual lists fever, dehydration and mouth breathing among the causes of whitish tongue coatings; with time, and with stains from food, drink or tobacco, that coating can look dull gray. A gray tongue with a sore throat is usually this, although the NHS notes that scarlet fever starts with a white coating on the tongue alongside a sore throat and fever, so a child with these symptoms and a rash needs a doctor.

Smoking and vaping

Tobacco both dries the mouth and stains the coating. The MSD Manual names smoking and chewing tobacco as causes of stained papillae. A smoker's coating often looks gray-brown rather than white.

Dehydration and dry mouth

Not drinking enough, sleeping with your mouth open, and medicines that dry the mouth all let the coating build faster.

Skipped tongue cleaning

Brushing your teeth does not clean the top of the tongue. Without daily cleaning, the coating thickens and takes on color from coffee, tea and food.

• Geographic tongue. Cleveland Clinic notes that people with geographic tongue may develop whitish-gray borders around smooth red areas. The pattern moves over days or weeks. It is harmless. See our geographic tongue guide.
• Oral thrush. In babies, the NHS describes a white coating on the tongue that may turn yellow or gray and look like cottage cheese. In adults, thrush leaves red, sore areas when the patches are rubbed off. It needs antifungal treatment.
• Eczema. Cleveland Clinic mentions a 2017 study in which many people with eczema had gray or pale tongues. The evidence is limited.
• A slate-gray spot. DermNet describes an amalgam tattoo, a fragment of silver filling in the tissue, as a blue, black or slate-gray patch. It is harmless, but any new or changing dark spot should be checked.
• Silver supplements. Colloidal silver can cause argyria, a bluish-gray discoloration that NCCIH says is usually permanent. Cleveland Clinic notes it can affect the gums.

The NHS describes cyanosis as blue or gray skin or lips, and advises calling emergency services if it is on the lips, tongue or face and comes on suddenly, or comes with difficulty breathing, chest pain, confusion or dizziness. Cleveland Clinic adds that on darker skin, cyanosis may look more gray or white than blue. So a gray tongue in someone with dark skin who is breathless or unwell should not be dismissed as a coating. Check the lips, gums and nail beds as well; if they are gray too, treat it as an emergency.

1. Rehydrate. Sip water regularly through the day, more if you have a fever.
2. Clean the tongue gently once or twice a day. Scrape or brush back to front with light pressure. If you are ill and your throat is sore, a few gentle passes are enough. Our tongue scraper guide covers technique.
3. Keep brushing and flossing even when you feel unwell.
4. Avoid tobacco while you recover, and ideally for good.
5. Ease a blocked nose so you are not mouth breathing at night.

An illness-related coating usually fades within a few days of eating and drinking normally again. If you see raw, red areas under the gray when you wipe it, stop scraping and ask a pharmacist or doctor about thrush.

See a dentist or doctor if the gray coating lasts more than two weeks after you recover, if it hurts or bleeds when wiped, if a baby under 4 months has a coating that looks like cottage cheese, or if you notice a gray or dark spot that does not wipe away. Call 911 for a sudden gray or blue tongue and lips, or any gray color with breathing difficulty, chest pain or confusion.