Why is my tongue blue?

• The tongue and lips turned blue or gray suddenly, with no blue food or drink to explain it
• Difficulty breathing, fast breathing, choking or noisy breathing
• Chest pain, confusion, dizziness, unusual drowsiness or collapse
• A baby or child with a blue tongue or lips who is struggling to breathe or feed, grunting, flaring the nostrils, or whose chest sucks in with each breath

These are the warning signs listed by the NHS and Cleveland Clinic for cyanosis. The NHS advises not driving yourself to the emergency room. The call handler will tell you what to do while you wait.

Oxygen-rich blood is bright red; blood low in oxygen is darker and looks blue through thin tissue. Cleveland Clinic separates two kinds of cyanosis:

• Peripheral cyanosis affects only the hands, feet, fingers or toes, often from cold or tight clothing. It is rarely life-threatening.
• Central cyanosis shows in the tongue, lips, gums, cheeks or chest. It means the blood leaving the heart is low in oxygen, and Cleveland Clinic says serious heart, lung or blood conditions may be the cause.

That is why a blue tongue is more significant than blue fingers. Many newborns have bluish hands and feet in their first hours (acrocyanosis), which is normal, but a blue tongue or lips in a baby is not.

Color can be harder to see on brown or black skin. Cleveland Clinic notes cyanosis may look more gray or white on darker skin, and the NHS suggests checking the tongue, gums, lips and inside of the eyelids.

The causes of central cyanosis listed by the NHS and Cleveland Clinic include:

• Airway problems: choking, croup, epiglottitis
• Lung problems: asthma attacks, pneumonia, COPD, pulmonary embolism, high altitude
• Heart problems: heart failure, congenital heart defects, cardiac arrest
• Other: seizures, drug overdose and toxic exposures

A rarer cause is methemoglobinemia, where hemoglobin carries oxygen but cannot release it properly. MedlinePlus lists bluish skin as the main sign and names the numbing agent benzocaine, some antibiotics such as dapsone, and nitrites among the triggers, alongside inherited forms. Headache, dizziness, tiredness and shortness of breath can come with it, and severe shortness of breath is a reason to call 911.

Blue food dye

Blue raspberry candy, freezer pops, slushies, frosting, sports drinks and blue cereals are by far the most common reason a healthy person sees a blue tongue. The dye clings to the rough papillae and sits on the surface. The lips and gums are their normal color, the person feels completely well, and the blue fades within a few hours.

A blue-black spot

A single small blue, black or slate-gray spot, often near a filling or on the underside of the tongue, can be an amalgam tattoo: a fragment of silver filling lodged in the tissue. DermNet and the MSD Manual describe these as harmless. Because a mole or melanoma can look similar, any new or changing dark spot should still be examined.

Veins under the tongue

The underside of the tongue always looks somewhat bluish because large veins lie close to the surface. Prominent ones are common with age.

Colloidal silver

Taking colloidal silver can cause argyria, a buildup of silver that turns tissue bluish-gray. The NIH's NCCIH says this discoloration is usually permanent, and Cleveland Clinic notes it can affect the gums.

Dye stain fades on its own, but you can speed it up:

• Drink water and eat a normal meal; saliva and food wash dye off the surface.
• Brush your teeth, then gently brush or scrape the tongue from back to front.
• Avoid harsh scrubbing or hydrogen peroxide. They irritate the tongue and are not needed.

If the blue has not faded by the next day, or the lips and gums look blue too, it is not a dye stain. See a doctor, and call 911 if there are any breathing or chest symptoms.

If you ate or drank something blue the evening before, overnight staining is the likely answer. If not, take it seriously. Look at your lips and nail beds in good daylight, and notice how you are breathing. A blue tongue on waking with breathlessness, chest pain, confusion or unusual sleepiness needs emergency care. A blue tongue that persists without symptoms still needs a same-day medical review to check oxygen levels.