Oral thrush Dr Trisha Macnair Oral thrush, also known as candidiasis or moniliasis, is an infection of the mouth caused by a yeast called Candida albicans.

In this article

What's the cause? What are the symptoms?

Who's affected? What's the treatment?

The yeast Candida albicans is all around us. Most people have some on their skin and it can be found in the mouths of more than half of us, but it doesn't usually cause any problems.

However, if the immune system is weakened or the normal environment of the mouth changes (if the healthy bacteria are killed, for example, or if too little saliva is produced or the acidity of the mouth changes) then candida yeasts may grow and cause symptoms.

Oral thrush usually causes white, creamy or yellow raised spots on the surface of the pink membranes in the mouth. These are sometimes described as having a 'cottage-cheese' or 'curd-like' appearance, and can be confused with milk residues on a baby's tongue after a feed.

The spots can be scraped off, leaving a tender, red area beneath, which may bleed. The spots are usually limited to the mouth but may spread down the throat. They're not usually very painful but may interfere with feeding.

Older children and adults may complain of burning or soreness in the mouth or throat, or at the angles of the lips. Thrush doesn't usually cause a temperature - if your baby has a fever get medical advice.

Severe thrush may be a sign of an important underlying illness but this is rare in small babies.

Oral thrush is common in newborn babies but rarely linked to any serious problems. In children and adults, exposure to the factors that encourage the growth of candida may lead to thrush.

These factors include anything that reduces natural resistance, such as general illness, viral infections, antibiotics (which kill off the protective bacteria in the mouth) and other medications, including the steroids often used in asthma treatments.

Almost everyone who wears dentures will have candida in their mouths but problems only tend to develop when they don't fit properly and damage the delicate membranes in the mouth.

In most cases, especially in babies, thrush can be diagnosed simply by looking at the spots. In difficult cases a sample may be scraped off and sent to the laboratory for analysis.

If there are predisposing causes (especially in older children or adults) these should be investigated and treated first.

Otherwise, treatment consists of anti-fungal medicines such as nystatin (which can be given as drops or pastilles) or miconazole.

It's unusual for a breastfeeding baby to develop thrush, but if this happens the mother should use an antifungal cream on her nipples to prevent cross-infection between mother and child.

In bottle-fed babies, the bottle teats should be thrown away and new ones bought because the yeast may get into the teats and cannot be easily eradicated.

Oral thrush usually responds quickly to these treatments. If it persists, it may be necessary to check for any underlying illness that could be causing it.

This article was last medically reviewed by Dr Rob Hicks in July 2006.