What is thrush?

Thrush is an infection of the mouth caused by the Candida fungus, also known as yeast. Candida infection 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. They are normally kept in check by other bacteria and microorganisms in the body. However, certain illnesses, stress, or medications can disturb this balance, causing the fungus Candida to grow out of control and cause 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:

Factors that make Candida infection more likely to develop include:

  • Uncontrolled diabetes
  • HIV infection
  • Cancer
  • Dry mouth
  • Pregnancy (caused by the hormonal changes that occur with pregnancy)
  • Smoking
  • Wearing dentures that don’t fit properly

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 a little 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
  • A feeling that food gets stuck in the throat or mid-chest area
  • 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.

Cleveland Clinic is a non-profit academic medical center. Advertising on our site helps support our mission. We do not endorse non-Cleveland Clinic products or services. Policy