Oral thrush is a common and usually harmless fungal infection in the mouth. It mostly affects children under two years of age.

The main symptom of oral thrush is one or more white spots or patches in your baby's mouth. The patches can look like curd or cottage cheese.

Other symptoms include:

• refusing the breast or fussiness at the breast when you try to feed
• a whitish sheen to their saliva

Read more about the symptoms of oral thrush in babies.

Treating thrush in babies

Many cases of oral thrush clear up in a few days without the need for treatment.

If symptoms persist or they are particularly troublesome, ask your health visitor for advice or visit your GP.

There are several antifungal gels that can treat oral thrush. It is important to speak to your GP or pharmacist before you use them as some gels are not suitable for very young babies.

Read more about treating oral thrush in babies.

Why does my baby have oral thrush?

Oral thrush is caused by a strain of yeast fungus called candida albicans, which lives on the skin and inside the mouth of most people.

It doesn't cause symptoms usually, but it can cause an infection in people with a weakened immune system. As the immune systems of newborn babies are still developing, they are more vulnerable to infection.

Read more about the causes of oral thrush in babies.

Who is affected

Oral thrush is a common condition, affecting around 1 in 20 babies.

It is most common in babies around four weeks old, although older babies can get it too. Premature babies (babies born before 37 weeks) have an increased risk of developing oral thrush.

Symptoms of oral thrush can include one or more white spots or patches in and around the baby's mouth.

These may look yellow or cream-coloured, like curd or cottage cheese. They can also join together to make larger plaques.

You may see patches:

• on your baby's gums
• on the roof of their mouth (palate)
• inside their cheeks

You can easily rub the patches off. The tissue underneath will be red and raw. It may also bleed a little.

The patches may not seem to bother your baby. But if they are sore, your baby may be reluctant to feed.

Other symptoms

Other signs and symptoms of oral thrush in babies are:

• a whitish sheen to their saliva
• fussiness at the breast (keeps detaching from the breast)
• refusing the breast
• clicking sounds during feeding
• poor weight gain
• nappy rash

Some babies may dribble more saliva than normal if they have an oral thrush infection.

Many cases of thrush clear up without needing treatment. However, if these symptoms are particularly troublesome or persistent, ask your health visitor for advice or speak to your GP. 

Read more about treating oral thrush.

If there is any doubt about the diagnosis your GP can take a swab from your baby's mouth and send it to a lab to be tested.

Oral thrush is caused by a yeast fungus called candida albicans. Healthy people have this fungus in their mouths and it does not normally cause problems.

However, if the level of fungus increases too much (called overgrowth), membranes (mucosa) in your baby's mouth can become infected.

Immature immune system

Oral thrush may occur in babies because their immune systems take time to mature, making them less able to resist infection.

Oral thrush is more common in premature babies (babies born before 37 weeks of pregnancy) because:

• their immune systems are not as strong
• they have not had as many of their mother's antibodies passed to them

Antibiotics

Oral thrush infections can also happen after treatment with antibiotics. This is because antibiotics reduce the levels of healthy bacteria in your baby's mouth, which allows fungus levels to increase.

If you are breastfeeding and have been taking antibiotics for an infection, your own levels of healthy bacteria can be affected, making you or your baby more prone to a thrush infection.

In babies, oral thrush is not usually due to poor hygiene.

Mild oral thrush infections in babies often clear up after a few days without treatment.

However, if you are concerned, visit your GP. You can also ask your health visitor for advice, or call NHS Direct on 0845 4647.

Antifungal medicine

If your GP decides your baby needs treatment, they will probably prescribe an antifungal medicine.

If your baby is less than four months old, a medication called nystatin may be recommended.

In babies older than four months, a medication called miconazole is likely to be recommended. This is because there is a small risk of miconazole causing choking if it's not applied properly.

Nystatin

Nystatin comes as a liquid medicine (suspension). You put the liquid directly on the affected area using a dropper (oral dispenser) supplied with the medicine.

Nystatin does not usually cause any side effects and most babies will have no trouble taking the medication.

Miconazole

Miconazole is available as a gel. You apply the gel to the affected areas using a clean finger. It's important only to apply a little at a time and to try to avoid the back of your baby's mouth to reduce the risk of choking.

A small number of babies are sick after being treated with miconazole. This side effect usually passes and is not cause for concern.

General advice on treatment

Medication is most effective if you use it after your baby has had a feed or drink.

Continue to use the medicine for two days after the infection has cleared up as this will help prevent the infection from coming back.

If treatment hasn't cleared the thrush after seven days, contact your GP for advice.

Your GP will look in your baby's mouth and will be able to diagnose oral thrush based on the visible symptoms.

Taking swabs does not help with diagnosis as healthy babies carry the fungus in their mouths.

In most cases, there is no known cause for oral thrush infections in babies. Some doctors suggest that the steps below may help to prevent infection:

• If your baby uses a dummy, sterilise all their dummies regularly, as well as any toys designed to be put in their mouth, such as teething rings.
• If you bottle feed your baby, sterilise the bottles and other feeding equipment regularly, especially the teats.

Some doctors also suggest giving your baby a drink of sterilised water after a feed, to rinse away any milk left in their mouth.