A few specific habits, conditions, and medications are known to increase a person's likelihood of developing the condition. Causes of yellow tongue include:
Oral hygiene products with oxidizing agents
Some oral hygiene products, such as mouthwashes, rinses, and toothpaste, contain chemicals or particles that cause dry mouth, irritate skin cells on the tongue, or cause them to change color.
Common compounds that are known to cause yellow tongue discoloration include:
- witch hazel
Poor oral hygiene
Teeth and tongue cleaning help reduce bacteria on the surface of the tongue, reducing the risk of developing yellow tongue.
Tobacco products contain compounds and toxins that can discolor skin cells or irritate them. Tobacco can also cause cells to enlarge, increasing the chances of them trapping particles and bacteria.
Mouth breathing or dry mouth
Saliva naturally helps clear excess bacteria and particles from the tongue's surface. Dehydration reduces saliva production, so bacteria and food particles remain near cells, increasing the risk of bacterial overgrowth. Mouth breathing, especially at night, increases the risk of dry mouth.
Black hairy tongue
Black hairy tongue is a fairly common, non-cancerous condition where bacteria or fungi cause an enlarged, elongated, hair-like carpet to appear on the surface of the tongue. Although the tongue most commonly appears black, it may also turn yellow, blue, or green.
Most people only seek treatment for the condition due to its appearance, though others experience nausea, gagging, bad breath, and a burning sensation in the mouth.
Foods with dyes, colorants, or those that stick to the tongue
Many foods contain dyes or colorants that can stain the tongue yellow, or are sticky and remain stuck to the tongue, discoloring its surface.
Certain medications and drugs
Several medications and drugs also contain staining particles, cause pigment discoloration, or weaken the immune system.
Common substances and medications that may increase the likelihood of developing yellow tongue include:
- diabetes and many diabetes management medications
- blood-thinning medications
- lansoprazole (Prevacid)
- chlorhexidine (found in some disinfectant mouth rinses)
- iron salts
- bismuth subsalicylate
- cancer and radiation medications
- antipsychotic medications
Some Illicit drugs, such as cocaine, can also cause the tongue to discolor.
Overgrowth of the bacteria Candida can cause white patches on the tongue that eventually develop a yellow tone.
Geographic tongue is a non-cancerous condition that causes red or white patches on the top and sides of the tongue that are often surrounded by a yellow border. The condition has no known cause but primarily affects children between the ages of 4 to 5. Patches tend to occur where skin cells are missing and occasionally are painful.
In people with jaundice, bilirubin, a chemical created by the breakdown of red blood cells, builds up abnormally in tissues. Sometimes, only specific parts of the body become yellowed, such as the whites of the eyes.
Other times, the entire skin may take on a yellow glow or hue. Unlike many of the causes of yellow tongue, jaundice requires immediate medical attention and often treatment as it is might be a sign of life-threatening conditions, such as liver failure.
Eczema and autoimmune conditions
Some autoimmune conditions such as eczema weaken the body's immune system, allowing otherwise harmless bacteria to overgrow on the tongue. In a 2017 study, out of 35 individuals with yellow tongue coating, 32 had acute or severe eczema.
In the same study, out of 122 patients with white tongue coating, only three had acute eczema.
Gastric conditions and infections
Conditions that cause inflammation of the gastric lining have been known to cause yellow tongue coating. Several studies have confirmed that a yellow, thickened tongue coating is associated with chronic cases of gastritis or inflammation of the stomach lining, especially when caused by the bacteria Helicobacter pylori.