What is oral thrush?

Oral thrush, also known as oral candidiasis, is an infection in your mouth. Oral thrush is usually caused by a type of yeast fungus known as Candida.

Oral thrush causes changes in your mouth, such as:

• white patches
• sores in the corners of your mouth
• a burning feeling

Candida can cause infections in other moist areas, such as skin folds.

What causes oral thrush?

Oral thrush is caused by a fungus called Candida. There are different types of Candida that can cause oral thrush, but Candida albicans is the most common.

Around 1 in every 2 people have Candida in their mouth, but it does not always cause oral thrush. Candida causes oral thrush when the fungus multiplies and affects the lining of your mouth.

You are more likely to develop oral thrush if you:

• are an older adult
• have a chronic medical condition, such as cancer or diabetes
• take certain medicines such as antibiotics or inhaled corticosteroids
• smoke or vape
• have a dry mouth — this may be due to problems with your salivary glands or some medicines such as antihistamines
• have nutritional deficiencies
• wear dentures or have poor oral hygiene

Newborn babies and infants can get oral thrush:

• during breastfeeding, if their mother has nipple thrush
• during vaginal delivery, if their mother has vaginal thrush

Read more about oral thrush in children.

What are the symptoms of oral thrush?

Oral thrush often causes white patches in your mouth that can be wiped away to leave red areas that may bleed.

Other symptoms may include:

• pain or burning in your mouth
• changes to your tongue, such as red or smooth patches
• an unpleasant taste in your mouth
• changes to your sense of taste
• cracks or sores at the corners of your mouth
• sores underneath your dentures

When should I see my doctor?

You should see your doctor if you think you have oral thrush.

You should also see your doctor if:

• your symptoms of oral thrush come back after treatment
• you have changes in your mouth that you are worried about

Many treatments for oral thrush are available at your local pharmacy without a doctor's prescription. If you have had thrush before and know what it feels like, talk to your pharmacist and consider an over-the-counter treatment.

How is oral thrush diagnosed?

Your doctor can diagnose oral thrush by:

• asking about your symptoms
• asking about your medical history
• examining the inside of your mouth

If your symptoms do not get better with treatment or the diagnosis isn't clear, your doctor may take a swab of your mouth. This can help them confirm the diagnosis and choose the best treatment for you.

In rare cases, your doctor may refer you for:

• an endoscopy — this is to see if you also have thrush further down your digestive tract
• a biopsy — this is to rule out mouth cancer
• a blood test or urine test — this is to check for other conditions such as diabetes

How is oral thrush treated?

Self-care at home

Oral thrush can often be managed at home with good oral hygiene:

• Brush and floss your teeth regularly.
• Use warm saline water as mouthwash.
• If you wear dentures, make sure that they are cleaned properly. Take your dentures out overnight.
• Rinse your mouth after every meal.
• Drink plenty of water.

Medicines for oral thrush

Oral thrush is treated with topical antifungal treatments such as antifungal lozenges.

In some cases, your doctor may prescribe antifungal medicine as a tablet.

You will usually need to continue treatment for 1 to 4 weeks, or until you have had no symptoms for 7 days.

Every treatment is different, so ask your doctor or pharmacist if you have any questions.

What are the complications of oral thrush?

Complications of oral thrush are rare, but may include:

• the infection spreading to your oesophagus (food pipe)
• the infection spreading to other parts of your body
• liver problems caused by antifungal medicines

How can I prevent oral thrush?

Here are some tips to prevent oral thrush:

• If you use inhaled corticosteroids, gargle with water and then rinse your mouth after each inhalation.
• Avoid using antiseptic mouthwashes. These can change the balance of 'good' bacteria in your mouth, allowing Candida to grow and cause oral thrush.
• If you smoke or vape, try to cut down or quit.
• Reduce the amount of sugar in your diet.

Resources and support

The DermNetNZ page has more information about oral thrush.

If you or someone you know has diabetes, learn more about protecting your oral health at Diabetes Australia.

If you or someone you know has asthma or uses an inhaler, the Australian Dental Association has information about preventing oral thrush.

You can also call the healthdirect helpline on 1800 022 222 (known as NURSE-ON-CALL in Victoria). A registered nurse is available to speak with you 24 hours a day, 7 days a week.