Oral thrush

Also known as candidiasis or candidosis

Oral thrush is an infection in the mouth usually caused by the fungus (yeast) Candida albicans.

Key points

  1. According to the New Zealand Dermatological Society, 50% of people carry candida in their mouths.
  2. It only causes a problem when the yeast is able to reproduce and invade the moist surfaces of the mouth (called the mucosae), creating inflammation and tissue damage.
  3. Anyone can develop oral thrush, but it is more common in babies and older people.

Causes

Candida is kept at bay by a fine balance of conditions in the mouth. When this balance is upset, either through an underlying condition or the use of medications, the candida is able to grow more quickly and create an infection. Some of the factors that make a person more likely to develop thrush include:

Symptoms

undefinedOral thrush is usually quite easy to identify by looking in the mouth. Symptoms may include:

  • A white or cream-coloured patch on the tongue, the inside of the cheeks, or the roof of the mouth (red or bleeding tissue may be revealed if the white layer is scraped off).
  • Red and sore patches in the soft patches of the mouth, tongue or roof of mouth, especially in denture wearers.
  • Pain in the mouth.
  • Red sores and cracks in the corners of the mouth.
  • Fussiness and not feeding well in babies.

In a breastfed baby with oral thrush, the mother may also have symptoms in one or both breasts:

  • red, sensitive or itchy nipples
  • flaky or shiny skin on the areola (the dark area surrounding the nipples)
  • pain in the breast or nipples during or between feeds.

Treatment

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For most people, oral thrush is mild and can be resolved either by:

  • Warm salt water rinses with half a teaspoon of salt in one cup of water, rinse and spit out, don’t swallow.
  • Sterilisation of dummies, bottles and teats.
  • Oral antifungal medication (prescription only).

Antifungal medication

  • Babies birth to six months: 
    • Nystatin suspension (Nilstat Oral drops), 1 ml, four times per day, for seven days.
  • Child six months to two years: 
    • Nystatin 1.25 ml (¼ teaspoon) four times daily, smeared around the mouth, avoiding the back of the throat to prevent obstruction.
  • Adult and child over two years: 
    • Nystatin 2.5 ml (½ teaspoon) in the mouth after food, four times daily, kept near the lesions before swallowing.
  • Dentures:
    • Nystatin gel may be applied directly to denture in evening and leave overnight.
  • Duration: 
    • Treatment should be continued for at least one week after the symptoms have disappeared.
  • Refer: 
    • Seek specialist advice if oral thrush persists after 2 weeks of treatment with oral anti-fungal medication. Recurrent or persistent thrush may indicate an underlying condition that requires treatment.

In people with reduced immunity, thrush can be more troublesome and widespread and may require treatment with intravenous (medicine injected into the vein) or oral medication.

Prevention

  • Make sure that all feeding equipment, dummies and toys that have been in contact with the baby’s mouth are sterilised.
  • For breast-feeding mothers the same product used for the baby may be used on the mother’s nipple.
  • In older children with asthma and on inhaled corticosteroids, use a spacer, rinse the mouth with water afterwards and reduce dose of steroid if appropriate. NOTE: Tooth brushing after using an inhaled corticosteroid is not recommended. The reduction in oral pH caused by the inhaler, and the mechanical abrasion from the toothbrush, increases tooth surface loss.
  • Practice good oral hygiene.
  • Eat natural yoghurt or take probiotics, e.g. acidophilus, particularly if you are taking antibiotics.
  • Carefully clean dentures every day. 

Learn more

Oral candidiasis DermNet NZ, 2013
Oral thrush in newborns – a parent's guide Family Doctor NZ, 2015