You see: strawberry red

It could mean: you have a vitamin deficiency. A glossy, bright red tongue may be a sign your body is lacking iron or B12. “Vitamin B12 and iron are needed to mature papillae (small bumps) on the tongue,” says Dr Naomi Ramer. “If you are deficient in those vitamins, you lose those papillae, which can make your tongue appear very smooth.” If you are experiencing a vitamin deficiency you’ll most likely notice other symptoms as well, such as fatigue, weakness, balance problems, and memory difficulties.
In severe cases, this can cause pain when eating hot liquids or spicy food. Vegetarians are especially prone to low levels of B12, which is found in certain meats. “If you notice your whole tongue is a strawberry red colour, and you are a vegetarian, ask your doctor about taking supplements,” says Dr Dale Amanda Tylor. Notable vitamin deficiencies can also be associated with an autoimmune disease in the gastrointestinal (GI) tract, in which the stomach doesn’t absorb vitamins.
You see: brown or black fuzz

It could mean: you don’t have the best oral hygiene or tongue health. A tongue covered in dark hairs (actually called black hairy tongue) may look nasty, but doctors agree that it’s not cause for major concern. “We have papillae, small bumps on the surface of our tongue, which grow throughout our lifetime,” explains Dr Ada Cooper.
Papillae are normally worn down by chewing and drinking, but sometimes they can become overgrown, which makes them more likely to harbour bacteria or become discoloured from food. This can cause bad breath or taste abnormalities. “Typically [black and hairy tongue] is brought on by smoking, drinking coffee and dark teas, or poor dental hygiene,” says Dr Jack Krikor Der-Sarkissian. “Removing the offending cause, like smoking, and brushing the tongue or using a tongue scraper, may be all you need.”
These useful tips will help you say goodbye to bad breath for good.
You see: cottage cheese white

It could mean: you have a yeast infection. A lumpy, white-coated tongue could be thrush, an oral yeast infection caused by overproduction of candida. The condition is often linked to antibiotics. “Your tongue is home to naturally occurring bacteria and yeast. When you take an antibiotic, which selectively kills off bacteria, it can allow yeast, which is not killed by antibiotics, to take over,” says Dr Tylor. Thrush, which might cause taste disturbances or a bit of pain, can also occur in those with weakened immune systems. Typical in young children, thrush also affects people with autoimmune diseases, people with diabetes that isn’t well managed, chemotherapy patients, and the elderly. If you suspect you might have thrush, see your doctor.