What causes a brown tongue?

The first question is whether the brown is on the tongue or in it.

• Brown coating is a film over the top of the tongue. It is usually thicker toward the back, looks slightly furry or matte, and comes away, at least partly, when you scrape or brush. This is by far the most common pattern.
• Brown pigment is color in the tissue itself. It looks like a flat, sharply edged freckle or patch, does not budge when scraped, and may be on the sides or underside of the tongue rather than the top.

A coating is a cleaning problem with a cleaning fix. Pigment needs a different line of thinking, covered further down.

Coffee, tea and tobacco

The papillae on the tongue are rough enough to hold debris, and the MSD Manual notes that smoking, chewing tobacco, certain foods and colored bacteria can stain them. Several cups of coffee or black tea a day, or any tobacco use, is the single most common reason a coating turns from white or yellow to tan and brown.

Not cleaning the tongue, soft diet, dry mouth

Brushing your teeth does little for the tongue's top surface. Without daily cleaning, plus the friction from chewing rough foods and a steady flow of saliva, the coating builds up and has time to stain. Dehydration, mouth breathing and medicines that dry the mouth all speed this up.

Early black hairy tongue

When the filiform papillae shed too slowly and lengthen, they trap even more pigment. Cleveland Clinic says black hairy tongue is most often black or brown, and DermNet describes it as usually brown or black. A brown tongue that looks furry rather than just stained may be an early stage of it. Antibiotics, heavy coffee, tobacco, alcohol and peroxide mouthwashes are known triggers.

Chlorhexidine mouthwash

MedlinePlus says chlorhexidine rinse, often prescribed after gum treatment or surgery, may stain your teeth, tongue and dental repairs. The staining is brown and builds with regular use. Do not stop a prescribed rinse early; ask your dentist about managing the stain.

Bismuth (Pepto-Bismol)

A bismuth stomach remedy usually gives a darker, gray-black color, but a light dose can look brown. It fades within days of stopping. See black tongue from Pepto-Bismol.

Brown color in the tissue has a different set of causes, and most of them are not hygiene-related:

• Natural (physiologic) pigmentation. The MSD Manual notes that hereditary brown areas in the mouth are particularly common in people with darker skin and people of Mediterranean descent. These are lifelong, even and painless.
• Smoking. Heavy smoking can cause dark brown discoloration of the mouth lining called smoker's melanosis, usually on the gums.
• Medicines. A published review lists antacids, some antibiotics, antidepressants, blood pressure drugs and others among medicines linked to flat, smooth pigmentation of the tongue, which usually fades after the medicine is stopped.
• Addison's disease. NIDDK lists darkening of the lips and of mucous membranes, such as the lining of the cheek, among the signs of this hormone condition, usually with tiredness, weight loss and dizziness on standing.
• Melanoma. MSD notes that some cancers, including malignant melanoma, can cause dark color changes in the mouth. This is rare but is the reason a new, changing or irregular brown patch should always be examined.

1. Scrape once or twice a day. Reach as far back as is comfortable, pull forward with light pressure, rinse and repeat three or four times. Most of the brown film should lift within a few days. Our step-by-step scraping guide covers technique and gag reflex tips.
2. Rinse with water after coffee or tea. It will not stop staining entirely, but it removes much of the pigment before it settles into the coating.
3. Cut back or stop tobacco. It is the most stubborn stain source and a major trigger for hairy tongue.
4. Drink more water through the day so saliva can keep rinsing the tongue.
5. Swap oxidizing mouthwashes (peroxide-based) for a plain alcohol-free rinse.

If the brown is thick, has been there for weeks, or the tongue looks furry, give it two weeks of daily scraping before judging the result. Hairy tongue papillae take time to shorten.

Simple staining usually improves within a few days of daily cleaning. Black hairy tongue, including its brown form, typically settles within one to two weeks, according to Cleveland Clinic. Chlorhexidine staining lingers while you use the rinse and needs a dental cleaning to remove from teeth. Pigment does not clear with cleaning at all, which is itself a useful test: if two weeks of scraping change nothing, the color is probably not a coating.

Book a dental visit if a brown coating does not improve after two weeks of daily cleaning, if the tongue hurts or burns, or if you think a medicine started it. Get a flat brown or black patch examined sooner, especially if it is new, has an irregular edge, is raised, or is growing. See a doctor promptly if darkening in the mouth comes with fatigue, weight loss, salt cravings or dizziness when you stand, since those together can point to an adrenal problem.