Is a black tongue dangerous?

Usually not. Bismuth staining and black hairy tongue are both harmless and reversible. The exceptions are a distinct dark spot that does not wipe away, which should be examined, and black tongue that comes with symptoms such as pain or black stools unrelated to medicine.

Why did I wake up with a black tongue?

The most common reason is a bismuth stomach remedy taken the evening before. Overnight, saliva flow drops and the bismuth has time to react on the tongue surface. If you took nothing like that, slowly building hairy tongue is the next most likely cause, and it often becomes noticeable in the morning when the coating is thickest.

How long does a black tongue last?

Bismuth darkening usually fades within a few days of stopping the medicine. Black hairy tongue typically clears within one to two weeks once you clean the tongue daily and cut back on triggers. If it lasts longer, see a dentist.

Can antibiotics turn your tongue black?

Yes. Antibiotics can shift the balance of bacteria and yeast in the mouth, and several, including penicillins, erythromycin and tetracyclines, have been linked to black hairy tongue. It normally improves after the course ends. Keep taking the antibiotic unless the prescriber tells you otherwise.

Is black hairy tongue contagious?

No. It is an overgrowth of your own tongue papillae and the normal mouth bacteria living on them. Cleveland Clinic notes that sexually transmitted infections do not directly cause it.

Black Tongue: Causes, Pepto-Bismol and When to Worry

What a black tongue usually is

The black color almost never comes from the tongue tissue itself. In most cases it sits on the surface: either a chemical deposit from a medicine, or a layer of debris and bacteria held in place by the tiny threadlike bumps (filiform papillae) that cover the top of the tongue.

Those papillae normally shed and renew. When they shed too slowly, they lengthen, trap food pigments and bacteria, and the tongue can look black, brown or furry. Cleveland Clinic describes this black hairy tongue as temporary, harmless and fairly common, especially in men over 65. MedlinePlus puts it bluntly: a black or brown tongue is unsightly, but it is not harmful.

The searches people run for a "black tongue medical condition" are usually looking for one of the causes below, so it helps to work through them in order of how often they happen.

Common causes of a black tongue, from most to least likely

1. Pepto-Bismol and other bismuth products

Bismuth subsalicylate, the active ingredient in Pepto-Bismol and many store-brand stomach remedies, reacts with sulfur compounds in the mouth to form a black salt (bismuth sulfide). The tongue can turn black within hours of a dose, sometimes along with black stools. MedlinePlus says the darkening is harmless and usually goes away a few days after you stop the medicine. A Pepto tongue is typically smooth and evenly dark, without the furry texture of hairy tongue. Our page on black tongue from Pepto-Bismol covers this in detail.

2. Black hairy tongue

The tongue looks fuzzy or furry, most often toward the back, while the tip and sides stay pink. Cleveland Clinic and DermNet list the usual triggers:

Not cleaning the tongue, and a soft diet that does not rub the papillae down
Smoking or chewing tobacco
Heavy coffee or tea drinking, and heavy alcohol use
Dry mouth or dehydration
Antibiotics and some other medicines (DermNet names penicillin, erythromycin, tetracyclines, lansoprazole and olanzapine, among others)
Frequent peroxide or chlorhexidine mouthwash
Radiation therapy to the head and neck, and conditions that weaken the immune system

3. Staining without overgrowth

Tobacco, coffee, black tea, some foods and colored bacteria can stain normal-length papillae, according to the MSD Manual. This gives a patchy gray-brown to black film that scrapes or brushes off and returns if the habit continues.

4. A dark spot rather than a dark tongue

A single blue-black or slate-gray spot, often on the underside or side, is a different situation. It can be an amalgam tattoo (a fragment of silver filling lodged in the tissue), which is harmless, but a mole or melanoma can look similar. Any dark spot that is new, raised or changing needs a professional look.

How to tell the causes apart

Clue	Pepto / bismuth	Black hairy tongue	Dark spot or patch
Onset	Hours after a dose	Builds over days to weeks	Often noticed by chance
Texture	Smooth	Furry, "hairy"	Flat or raised, smooth
Where	Whole top surface	Middle and back of tongue	One defined area
Scrapes off?	Partly	Gradually, over days	No
Clears when	A few days after stopping the medicine	1-2 weeks of daily cleaning	Does not clear; needs assessment

If you are unsure, the tongue color checker walks through the same questions.

What to do at home

Stop the obvious trigger. If you took Pepto-Bismol in the last day or two, wait it out; the color should fade on its own. Do not stop a prescription medicine on your own; ask the prescriber if you suspect it.
Clean the tongue every day. Cleveland Clinic and DermNet both recommend gently removing the overgrowth with a tongue scraper or soft toothbrush. Scrape back to front, rinse the scraper, repeat a few times. Our guide to scraping a hairy tongue covers technique.
Drink more water and cut back on coffee, tea and alcohol while it clears.
Pause peroxide or oxidizing mouthwashes and use a plain, alcohol-free rinse instead.
Stop or reduce tobacco. It is one of the most consistent triggers.

Most hairy tongue cases improve noticeably within a week of daily cleaning and clear within two.

Treatment a professional may use

A dentist or doctor can usually diagnose black hairy tongue just by looking. If cleaning has not worked, Cleveland Clinic notes they may treat a bacterial or yeast overgrowth with an antimicrobial or antifungal, or suggest a topical retinoid. Trimming the papillae with a laser is a rare last resort. They will also review your medicines and check that a dark area is not a pigmented lesion that needs a biopsy.

When a black tongue needs to be checked

See a dentist or doctor if the black color has not improved after two weeks of daily tongue cleaning and stopping obvious triggers, or straight away if you see a defined dark spot rather than a coating. If you also have black, tarry stools and you have not taken bismuth or iron, that can signal bleeding in the upper digestive tract and needs prompt medical attention, according to MedlinePlus.

Why is my tongue black?