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Thrush is an infection of the mouth caused by the Candida fungus, also known as yeast. Candida infection is not limited to the mouth; it can occur in other parts of the body as well, causing diaper rash in infants or vaginal yeast infections in women.

What causes thrush?

Small amounts of the Candida fungus are present in the mouth, digestive tract, and skin of most healthy people and are normally kept in check by other bacteria and microorganisms in the body. However, certain illnesses, stress, or medications can disturb the delicate balance, causing the fungus Candida to grow out of control and causing infection.

Thrush can affect anyone, though it occurs most often in babies and toddlers, older adults, and people with weakened immune systems. Examples of medications that upset the balance of microorganisms in the mouth include corticosteroids, antibiotics, and birth control pills. Illnesses or medical situations that make Candida infection more likely to develop include uncontrolled diabetes, HIV infection, cancer, dry mouth, or pregnancy (caused by the hormonal changes that occur with pregnancy). People who smoke or wear dentures that don’t fit properly also are at increased risk for thrush. In addition, babies can pass the infection to their mothers during breast-feeding.

While healthy children and adults can be effectively treated, the symptoms may be more severe and difficult to manage in those with weakened immune systems.

What are the symptoms of thrush?

Thrush usually develops suddenly, but it may become chronic, persisting over a long period of time. A common sign of thrush is the presence of creamy white, slightly raised lesions in your mouth -- usually on your tongue or inner cheeks -- but also sometimes on the roof of your mouth, gums, tonsils, or back of your throat. The lesions, which may have a "cottage cheese" appearance, can be painful and may bleed slightly when you scrape them or brush your teeth. In severe cases, the lesions may spread into your esophagus, or swallowing tube, causing the following symptoms:

  • Pain or difficulty swallowing
  • Fever, if the infection spreads beyond the esophagus

Thrush can spread to other parts of the body, including the lungs, liver, and skin. This happens more often in people with cancer, HIV, or other conditions that weaken the immune system.

How is thrush diagnosed?

Your dentist can make the diagnosis by examining your mouth. He or she looks for the distinctive white lesions on your mouth, tongue, or checks. Lightly brushing the lesions away reveals a reddened, tender area that may bleed slightly. A microscopic examination of tissue from a lesion can confirm the diagnosis.

Thrush that may extend into your esophagus may require other tests to make the diagnosis. Such tests might include taking a throat culture (swabbing the back of your throat with sterile cotton and studying the microorganisms under a microscope), performing an endoscopy of your esophagus, stomach, and small intestine (examining the lining of these body areas with a lighted camera mounted on the tip of a tube passed through these areas), or taking x-rays of your esophagus.

How is thrush treated?

Antifungal medications, which are generally taken for 10 to 14 days, are often prescribed to treat thrush. These medicines are available in tablets, lozenges, or liquids that are usually "swished" around in your mouth before being swallowed. Your dentist will have a specific treatment approach designed for you based on your age and the cause of the infection. Because the presence of Candida infection can be a symptom of other medical problems, your dentist may suggest you seek care from a medical doctor as well so that any underlying health problems you have can be treated.

How can thrush be prevented?

The following practices can help minimize your chance of developing thrush:

  • Follow good oral hygiene practices: Brush your teeth at least twice a day and floss at least once a day.
  • Avoid mouthwashes or sprays: These products can destroy the normal balance of microorganisms in your mouth.
  • See your dentist regularly: This is especially important if you have diabetes or wear dentures.
  • Limit the amount of sugar and yeast-containing foods you eat: Foods such as bread, beer, and wine encourage Candida growth.
  • If you smoke, quit: Ask your doctor or dentist about ways to help you kick the habit.


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