Oral thrush is a condition that occurs when there is an overgrowth of the Candida fungus in the mouth.

Candida is a fungus that is present on and in the human body at all times, but most of the time it’s kept in check by other microorganisms. Oral thrush, also called candidiasis, occurs when this balance is upset and a Candida overgrowth happens in the lining of the mouth.

Causes for this can include the use of certain medications (like antibiotics or corticosteroids), hormonal changes in pregnancy, uncontrolled diabetes, HIV, cancer treatment and dry mouth. Smoking or wearing dentures are also risk factors for developing oral thrush.

A Candida overgrowth can also manifest as a vaginal yeast infection (vaginal thrush), nappy rash in babies or as a rash under large breasts.

What are its symptoms?

Oral thrush symptoms include:

  • Slightly raised sores with a ‘cottage cheese’ appearance in the mouth. These creamy, white lesions may be present on the tongue and inner cheeks and less commonly on the gums, roof of the mouth and back of the throat.
  • Slight bleeding if sores are scraped
  • Pain and difficulty eating or swallowing
  • Cracks in the corner of the mouth
  • Diminished sense of taste
  • Feeling as if food is getting stuck in the throat
  • Fever, if the infection spreads past the oesophagus.

How is it diagnosed?

An oral thrush diagnosis can usually be made by a healthcare provider identifying the characteristic white lesions in the mouth. In cases where the diagnosis needs to be confirmed, a sample of the fungus scraped from the inside of the mouth will be examined under a microscope.

In severe cases, a throat culture may be taken or an endoscopy – in which a flexible tube equipped with a tiny camera at the end is put down the throat to allow a doctor to see inside your oesophagus and stomach – may be performed to assess the extent of the infection.

What are your treatment options?

The mainstay for oral thrush treatment is antifungal medication. Prescribed by a doctor, this can include antifungal mouthwash and lozenges or stronger systemic medication – pills that treat the entire body, not just the affected area – may be prescribed.

It’s important that any underlying condition contributing to the Candida overgrowth be addressed too.

Can it be prevented?

Oral thrush prevention depends largely on maintaining the correct balance of microorganisms in the body. As such, it is important to take a probiotic whenever taking antibiotics – this is something you can discuss with your healthcare provider.

Oral hygiene – brushing and flossing your teeth regularly – is very important for lowering your risk of oral thrush, as is avoiding sugar and yeast in the diet – both cause the Candida fungus to flourish.

Quitting smoking can also help to reduce your oral thrush risk.

The accuracy of this information was checked and approved by physician Dr Thomas Blake in May 2015