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Oral thrush

What is oral thrush?

Oral thrush is a yeast infection in the mouth caused by the Candida albicans fungus.

Symptoms of oral thrush include sore, white patches in the mouth, an unpleasant taste in the mouth, a burning sensation affecting the tongue, and problems swallowing.

Oral thrush can affect people of all ages, including adults with weakened immune systems.

Thrush is caused by Candida yeast.

What causes thrush?

Small amounts of the Candida albicans 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 medication can disturb the delicate balance, causing the candida organisms to grow out of control, causing thrush.

Medication that upsets the balance of microorganisms in the mouth and may cause thrush include corticosteroids, antibiotics, and birth control pills. Illnesses or medical conditions that make candida infection more likely to develop include uncontrolled diabetes, HIV infection, cancer, dry mouth (perhaps caused by certain drugs), or pregnancy (caused by the hormonal changes that occur with pregnancy). People who smoke or who wear dentures that don't fit properly are also at increased risk of thrush. In addition, babies can pass the infection to their mothers during breast-feeding.

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 oesophagus (gullet) causing:

  • Pain or difficulty swallowing
  • A feeling that food gets stuck in the throat or mid-chest area
  • Fever, if the infection spreads beyond the oesophagus

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

How is thrush diagnosed?

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

Thrush that extends into your oesophagus may require other tests to make the diagnosis. Such tests might include taking a throat culture - swabbing the back of your throat with a sterile cotton bud and studying the micro-organisms under a microscope - and performing an endoscopy of your oesophagus, stomach and small intestine. This involves examining the lining of the gullet and bowel with a lighted camera mounted on the tip of a tube passed through these areas. A special X-ray of your oesophagus may also be taken.

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WebMD Medical Reference

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