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Oral thrush (oral candidiasis) is a yeast infection that forms due to the overgrowth of Candida fungus. The most common type of Candida fungus that causes thrush is Candida albicans. These fungi live in the mucous membranes lining in the mouth.
Most people have small traces of Candida in their mouths. In some cases, the fungi can overgrow and cause thrush. However, if you have a strong immune system, the fungus does not overgrow. Thus, you will not develop this condition.
Candidiasis most commonly affects people with weakened immune systems, such as infants or adults taking certain medications. Although, the condition can affect people of all ages.
Thrush is difficult to notice, at least at first, and does not cause severe pain. The condition is also uncomfortable to deal with on a daily basis. Although, it typically doesn’t indicate a serious medical problem.
Candidiasis is a widespread condition that creates white spots (lesions) that wipe off but leave a red, raw base. The lesions can either develop on the tongue, palate, or buccal mucosa (lining of the cheeks and back of the lips). The condition may also cause mild burning.
Thrush can cause some, or all, of the following symptoms:
Thrush can be triggered by a variety of factors, including existing medical conditions and poor oral health:
Antibiotics are commonly prescribed to sick patients to fight off harmful bacteria. However, children and adults taking antibiotics may develop thrush symptoms because the medications also temporarily kill harmless bacteria. Thus, weakened immune systems create a perfect environment for Candida fungus to thrive.
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Dry mouth is an oral condition that occurs when the salivary glands in the mouth do not produce enough saliva to keep the mouth wet. Consequently, inadequate saliva production increases the risk of oral thrush.
Using an old toothbrush with harbored fungus can also cause thrush. It is recommended to switch toothbrushes or toothbrush tips at least every three months to prevent the spread of bacteria and fungus.
Herpes simplex virus type 1 (HSV-1) is a highly contagious infection that causes cold sores and may also cause mild candidiasis. HSV-1 is a lifelong disease that spreads through close personal contact, such as kissing, and sharing utensils.
Oral thrush is the most common fungal infection cancer patients get while receiving treatment. However, cancer treatments weaken the immune system, which can trigger the growth of Candida fungus.
Pregnant women are at a higher risk of developing oral candidiasis. This is due to extreme changes in hormones. If a woman has a yeast infection while giving birth, the infection can also be transferred to the baby during labor.
sing steroid medications long-term can cause this condition. Moreover, if you frequently use an asthma inhaler that contains steroids, you have an increased risk of developing oral candidiasis.
Pacifiers and baby bottles can make a baby’s mouth too moist, creating the ideal environment for yeast to grow in. So, to help prevent oral candidiasis, babies should not go to sleep with a bottle in their mouths and pacifier use should be limited throughout the day. In addition, thoroughly clean pacifiers and bottle nipples in the dishwasher or soak them in hot water after each use to remove bacteria and fungus.
The American Academy of Pediatrics recommends stopping pacifier use altogether after a baby turns 6 months old to prevent thrush, other oral conditions, and ear infections.
High levels of glucose make it easier for Candida fungus to grow. More specifically, diabetics who do not monitor their blood sugar accurately have a higher risk of developing yeast infections.
People who have diabetes, HIV/AIDS, or take steroid medications are also at risk of developing thrush. In these cases, thrush can be life-threatening.
Additionally, young children are more likely to develop the condition if they:
Thrush is a non-life-threatening infection that typically goes away within a few days to a week with proper treatment. If it doesn't resolve within this timeframe, contact your dentist as soon as possible.
To prevent this condition from developing, dentists recommend the following:
The best way to prevent thrush is to practice good oral hygiene. Children and adults should brush their teeth at least twice a day with fluoridated toothpaste. They should also visit a dentist every six months for teeth cleanings, use mouthwash regularly, and floss daily. Eating unsweetened yogurt can also reduce symptoms and discomfort of candida infections.
“Candida Infections of the Mouth, Throat, and Esophagus | Fungal Diseases | CDC.” Centers for Disease Control and Prevention, Centers for Disease Control and Prevention, https://www.cdc.gov/fungal/diseases/candidiasis/thrush/index.html.
Oral thrush: Overview. Cologne, Germany: Institute for Quality and Efficiency in Health Care (IQWiG); 2006. https://www.ncbi.nlm.nih.gov/books/NBK367586/.
“Oral Thrush.” Mayo Clinic, Mayo Foundation for Medical Education and Research, 8 Mar. 2018, https://www.mayoclinic.org/diseases-conditions/oral-thrush/symptoms-causes/syc-20353533.
Nowak, Arthur J. Pediatric Dentistry: Infancy through Adolescence. Elsevier, 2019.
“Thrush (Oral Candida Infection) in Children.” Thrush (Oral Candida Infection) in Children - Health Encyclopedia - University of Rochester Medical Center, https://www.urmc.rochester.edu/encyclopedia/content.aspx?contenttypeid=90&contentid=P02690.