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Oral thrush

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What is oral thrush?

Oral thrush, known as candidiasis, is a yeast infection that occurs in the mouth, the infection is caused by a group of yeast called Candida albicans. Usually harmless, the fungal infection is not contagious and commonly occurs when the natural bacterial balance in the body is disrupted.

Who is more at risk of developing oral thrush?

People most at risk of developing thrush are those with weakened immune systems, or those who have had a change within their mouths which allows the bacteria to grow, for example those who wear dentures.

You may develop thrush in your mouth if:

  • You’re very young as the immune system is still developing
  • You're pregnant as natural hormonal changes make you more susceptible
  • You are elderly as your immune system can be suppressed
  • You have diabetes, as this can affect the tissue inside your mouth
  • You have an infection that affects your immune system, such as HIV
  • You have a treatment that reduces your immunity, for example if you are having treatment for cancer

What causes thrush in the mouth?

The group of yeasts that cause oral thrush, are always present in your mouth, digestive system and on your skin in small quantities, in these amounts they are harmless. These yeasts are usually kept under control by other bacteria in your body, however during times of stress or ill health your natural bodily balance may be moved out of harmony. These changes can cause the candida organisms to grow and multiply uncontrollably, and it is this reaction that causes thrush and its symptoms to appear.

There are a number of reasons why oral thrush develops which include:

  • Antibiotics – taking a long course or high dose can increase your risk of developing oral thrush
  • Using an asthma inhaler
  • Wearing dentures, especially if they are ill fitting
  • Practising poor oral hygiene
  • Smoking
  • Having a dry mouth – this may be caused by medication or a medical condition
  • Having cancer treatment such as chemotherapy or radiotherapy

What does thrush look like?

Oral thrush commonly appears as a white coating in the mouth, you may notice white patches on your tongue, inner cheeks and back of the throat. Along with a discoloured mouth oral thrush causes inflamed red spots, bad breath and soreness. When aggravated these spots can bleed and become sore. Read our oral thrush symptoms guide to find out about other signs of oral thrush.

How is thrush in the mouth treated?

Oral thrush tends to be easy to treat, however the treatment your doctor will give you depends on the cause and severity of the infection. Find out more about how oral thrush is treated in our treatment guide

Are there any natural remedies for oral thrush?

Similarly to other oral infections, gargling salt water can help to relieve your symptoms and ease your throat. Also many people use prebiotic yoghurt to treat oral thrush, but make sure that you use unsweetened yoghurt as the yeast eats sugar and this causes it to grow.

Can you pass on oral thrush through kissing?

Oral thrush is not contagious however when you kiss somebody the bacteria from their mouth is transferred to yours. This means that the thrush yeast can enter your mouth or vice versa, this does not mean that you will get oral thrush, however it can develop if the circumstances are right.

I've had oral thrush in the past, can I get it again?

Yes, if you have had oral thrush before and received treatment then it does not mean that you are immune from getting the infection again.

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