What causes black spots on the tongue?

A "spot" is different from a whole black tongue. If the entire top of your tongue looks dark and furry, that is usually black hairy tongue, a coating problem. This page is about separate dots, freckles or patches that stay in one place.

Dark tongue spots fall into three broad groups:

• Pigment in the tissue itself - melanin, the same pigment that colors skin, sitting in the tongue lining. This does not scrape off.
• Something trapped or deposited - surface stain, dried blood, or tiny metal particles from old silver fillings.
• Blood vessels - a blood blister or a dilated vein, which tends to look dark red, purple or blue-black.

A quick self-check helps sort them: gently wipe the spot with gauze or run a clean tongue scraper over the area once. Stain and coating move or lighten. Pigment, blood blisters and filling particles do not.

Pigmented fungiform papillae

Fungiform papillae are the small mushroom-shaped bumps scattered over the tip and sides of the tongue. In some people the tips of these bumps hold extra melanin, which makes them look like a sprinkle of tiny black or brown dots. A 2023 review in PMC describes this as a benign pigment pattern that is relatively common in people with darker skin; it cites one US study that found it in 30% of Black women and 25% of Black men, and a South African study that found 6-8%. It needs no treatment.

Staining

Coffee, black tea, red wine, dark berries, licorice and tobacco can stain the rough surface of the tongue, especially where the coating is thicker. Bismuth subsalicylate (Pepto-Bismol) reacts with sulfur in saliva to form black bismuth sulfide. The NHS lists a black tongue as a common, harmless side effect that clears after you stop the medicine.

Blood blister or bruise

Biting your tongue, a sharp chip of food or a dental procedure can leave a small dark red to black blood blister. These usually fade within one to two weeks as the blood is reabsorbed.

Amalgam tattoo

DermNet describes an amalgam tattoo as a flat blue, black or slate-gray spot caused by a fragment of silver filling lodged in the mouth lining during dental work. It is most often on the gum next to a filling but can appear on the tongue. It is harmless and causes no symptoms.

• Smoker's melanosis: a reactive brown-black pigmentation seen in roughly 21-30% of smokers in published reviews. It usually affects the gums but can involve the tongue, and it tends to fade gradually after quitting.
• Medication pigment: some drugs, including certain antimalarials, minocycline, amiodarone and some chemotherapy agents, can darken areas of the mouth.
• Melanotic macule: a flat, evenly colored, well-defined freckle-like spot, usually under 1 cm. It is benign, but inside the mouth it often needs a biopsy to confirm, because there are no reliable visual rules that separate it from early melanoma.
• Oral melanoma: rare, but serious. It is more common on the palate and gums than the tongue. Warning features are a spot that is raised, growing, has irregular borders or uneven color, bleeds or ulcerates.

Widespread new dark patches in the mouth together with tiredness, weight loss, dizziness on standing or salt craving can point to Addison's disease, an adrenal problem that needs medical tests rather than oral care.

This table is a guide for deciding whether to book a visit, not a way to diagnose yourself. Photos taken a few weeks apart in the same light are useful to show your dentist.

• Stop or pause the likely stain source (coffee, tea, tobacco, bismuth) for a week and see if the spots fade.
• Clean the top of your tongue once a day with a scraper or soft brush to remove the stained coating. Do not scrub hard at a spot that does not move; it will not lift pigment and can cause a sore.
• Leave a blood blister alone. Do not pop it. Cool drinks help if it is tender.
• Do not stop a prescribed medicine you suspect is causing pigment without talking to the prescriber first.

Not sure whether you are looking at a spot or a coating? Our tongue color checker walks through the main differences.

Most dark spots are diagnosed by looking at them and asking about your history: how long the spot has been there, medicines, smoking and recent dental work. A dental x-ray can sometimes show filling particles behind an amalgam tattoo. If the cause is not clear, or the spot is raised, enlarging or irregular, the usual next step is a small biopsy under local anesthetic. A biopsy is the only way to rule out melanoma, and finding one early matters.