Oral thrush is a yeast infection of the inside of the mouth. Its main symptom is the appearance of creamy white spots on the tongue or insides of the cheeks. Oral thrush can cause discomfort but is not usually a serious condition. Treatment options include warm salt water mouth rinses and pharmacy medications.
Oral thrush occurs when a yeast infection develops on the tongue and inside of the mouth. It can occur at any age but most commonly affects infants and the elderly.
Oral thrush is generally a benign condition in healthy people but may cause problems for those with weakened immune systems. It can also be a sign of weakened immunity.
In people with lowered immunity, thrush may spread to the tonsils or back of the throat, which may make swallowing difficult. And left untreated, oral thrush can spread further and lead to a serious infection affecting the blood, heart, brain, eyes, bones, or other parts of the body.
Oral thrush in adults is not contagious. However, infants with oral thrush can pass on the infection to their mother’s nipples during breastfeeding.
Oral thrush is due to overgrowth of a candida yeast on the moist surfaces that line the inside of the mouth and tongue.
Candida, which is a type of fungus, is a normally harmless inhabitant of the skin and digestive tract. However, under certain conditions (such as an underlying health condition or use of some medications) candida can grow more quickly and create an infection.
The following are factors that can increase the risk of developing an oral thrush:
- Infancy or old age
- Weakened immunity due to cancer, certain immune system deficiency disorders, or infection with HIV
- Diabetes that is untreated or poorly controlled may result in high levels of sugar (glucose) in the saliva, which encourages the growth of candida
- Dry mouth due to disease of the salivary glands or certain medications, e.g. antihistamines, diuretics
- Broad-spectrum antibiotics, which can alter the normal balance of your body’s micro-organisms
- Inhaled corticosteroids and prednisone, which can weaken the local immunity
- Vaginal thrush infections during pregnancy, which can be passed to new-borns
- Thrush (candida) infection elsewhere in an infant, e.g. nappy dermatitis
- Dentures, especially if they fit badly or are not regularly cleaned
- Injury or trauma to the mouth
- Some types of nutritional deficiency, e.g. iron deficiency and/or B vitamin deficiency
Signs and symptoms
In adults and older children, signs and symptoms of oral thrush may include:
- Red inflamed areas in the mouth dotted with creamy white patches, which if wiped off leave red lesions that can bleed
- Cracks and redness at the corners of the mouth
- Loss of taste
- Unpleasant taste in the mouth
- Inside of the mouth may be painful, e.g. a sore tongue or sore gums
- Burning or soreness that makes eating and drinking difficult
- Redness and pain under dentures.
In infants, typical signs and symptoms of oral thrush are:
- Tongue is covered in a thick white coating that cannot be easily rubbed off
- White spots on the inside of the cheeks
- Fussiness, irritability, and feeding difficulties
- Nappy rash.
Women who develop candida infection of the breast may experience these signs and symptoms:
- Abnormally red, sensitive, cracked, or itchy nipples
- Nipple and areola may have a shiny appearance
- Pain in both nipples or breasts during or after feeds, which can be quite severe and last for up to an hour
- Stabbing or stinging pain deep within the breast.
A GP should also be consulted if oral thrush develops in older children, teenagers, or adults to check for an underlying medical condition or other cause.
Oral thrush can be diagnosed by its characteristic appearance. However, examination with a microscope and culture of skin swabs and scrapings can help to confirm a diagnosis of candida infection.
In cases where you have difficulty swallowing, an endoscopy (using an endoscope, which is a long, usually flexible tube with a lens at one end and a video camera at the other) may be performed to see the extent of the infection into the digestive tract.
Swabs may be taken if a candida infection of the nipples and breast is suspected in women who are breastfeeding, and who develop breast pain after feeds, having previously had no pain after feeding.
For babies, talk with your midwife, Plunket nurse, pharmacist or doctor about appropriate treatment options.
For adults or older children, warm salt water rinses (half a teaspoon of salt in one cup of water, rinse and spit out) can be used to treat mild cases. Antifungal mouthwashes and application of topical antifungal agents in the form of gel or lozenges can also be used (discuss appropriate options with your pharmacist).
Treatment should be continued for several weeks or until symptoms have been clear for at least one week.
More persistent or severe cases may require treatment with oral antifungal drugs prescribed by your doctor. See your doctor if there is no improvement after one week of treatment with saline mouthwash or an oral medication, or if you have difficulty or pain when swallowing.
An important measure to prevent oral thrush is to maintain good oral hygiene by:
- Brushing teeth regularly
- Using warm saline water as a mouth wash
- Avoiding use/overuse of antiseptic mouthwashes, which can alter the microbial flora of the mouth in some people. Drinking or rinsing with water and after inhalation of topical corticosteroid for asthma
- Sterilising dummies and feeding bottles after each use
- Treating dry mouth or a vaginal candida infection as soon as possible
- Removing dentures at night
- Keeping dentures clean, e.g. cleaning them with an anti-candida preparation
Further information and support
Freephone: 0800 611 116
Freephone: 0800 933 922
Mayo Clinic (2018). Oral thrush (Web Page). Rochester, NY: Mayo Foundation for Medical Education and Research. https://www.mayoclinic.org/diseases-conditions/oral-thrush/symptoms-causes/syc-20353533 [Accessed: 28/07/18]
Ministry of Health (2015). Candidal infections (Web Page). Wellington: New Zealand Ministry of Health. https://www.health.govt.nz/our-work/life-stages/breastfeeding/health-practitioners/candidal-infections [Accessed: 30/07/18]
NHS Choices (2017). Oral thrush (mouth thrush) (Web Page). Redditch: National Health Service (NHS) England. https://www.nhs.uk/conditions/oral-thrush-mouth-thrush/ [Accessed: 28/07/18]
Oakley, A. (2017). Oral candidiasis (Web Page). Hamilton: DermNet New Zealand. https://www.dermnetnz.org/topics/oral-candidiasis/ [Accessed: 28/07/18]
O’Toole, M.T. (Ed.) (2013). Thrush. Mosby’s Dictionary of Medicine, Nursing & Health Professions (9th ed.). St Louis, MI: Elsevier Mosby.
Updated: July 2018
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