What Is Oral Thrush?
Illustration of the yeast microbe Candida, which causes thrush.
Oral thrush (oropharyngeal candidiasis) is a superficial yeast infection of the mouth that may involve the tongue, inner cheek (buccal mucosa), inner lip region, and occasionally the gums (gingiva).
While it is most commonly seen in young infants, thrush may affect toddlers, and to a lesser degree, older children and occasionally adults. Oral thrush diagnosed in older children, teenagers, and any adult should always lead to a search for an underlying medical condition (diabetes, use of immunosuppressive therapy, etc.).
What Are Causes and Risk Factors of Oral Thrush?
Thrush is a yeast infection of the mouth and tongue. The infection is most common in older adults, babies, and those who have compromised immune systems.
Thrush is caused by an overgrowth of the yeast Candida albicans, which is commonly found on skin surfaces, the oral cavity, and throughout the intestinal tract of healthy individuals.
Newborn infants often are exposed to the fungus during vaginal delivery and may develop oral evidence of thrush within 10 days post-delivery. Breastfeeding infants may infect their mother's nipple area during breastfeeding. In addition, a Candida overgrowth in the stool may be associated with a characteristic diaper rash. Contamination of formula bottle nipples and pacifiers with the Candida fungus may also introduce the yeast into a child's oral cavity.
In older children and adults, oropharyngeal candidiasis is associated with several risk behaviors, including prolonged or repeated use of oral antibiotics, prednisone (or other steroid medications), smoking, dentures, use of birth control pills, and medical conditions especially diabetes (either type I or type II) or any diseases that can suppress your immune system (HIV/AIDS).
Perhaps the most common association for developing thrush is an improper technique during the use of inhalers containing corticosteroids for the control of asthma or COPD (chronic obstructive pulmonary disease). Such medications require rinsing your mouth with water and then spitting out the water to eliminate any non-inhaled medication. Patients using a metered-dose inhaler (MDI) for the administration of their steroids are recommended to use a "spacer" to lessen the amount of potential residual steroid left in the mouth.
Those individuals with the above risk factors may also develop Candida overgrowth of the esophagus. To confirm such a diagnosis requires an endoscopy. A gastroenterologist (GI doctor) performs this study. During the procedure, the doctor passes a flexible tube with a camera at the end from the mouth to the esophagus to the entry point into the stomach.
What Are Symptoms and Signs of Oral Thrush?
Oral thrush is characterized by a thick white coating of the tongue, inner cheeks, inner lip region, or gums. This coating may be differentiated from the very common off-white discoloration of the tongue associated with breast milk or infant formula debris by several means:
- Oral Candida infection is a very bright white color—milk debris is an off-white color.
- Oral Candida infections may also involve the buccal surface, inner lip area, and gingiva, while milk debris is limited to the tongue.
- Oral Candida is rather adherent to an involved skin surface while milk debris may more easily be wiped off with a damp facecloth.
Neither thrush nor milk debris cause discomfort nor other symptoms when limited to the mouth.
Maternal nipple/areola candidiasis commonly causes signs and symptoms like redness and tenderness of the involved area. The rash associated with Candida diaper dermatitis is generally not as bothersome as the more common diaper rash associated with irritation from excessive stool and urine contact with the infant's skin.
Is Oral Thrush Contagious?
Oral thrush is passed to a person via a number of mechanisms:
- Newborn infants may become exposed during a vaginal birth if their mother has a vaginal yeast infection.
- Utilization of Candida-contaminated bottle nipples may also cause exposure.
- Another mechanism to develop oral thrush is the overgrowth of the normally small amount of Candida in the mouths of older children, teenagers, and adults.
- Improper technique while utilizing an inhaled corticosteroid (not using a spacer) and failing to rinse and spit with water following usage of an inhaled corticosteroid are also common mechanisms leading to the development of oral thrush.
- Oral thrush is not transmitted from animals.
It is important to note that within a short time following birth all individuals have C. albicans on the skin, in the mouth, in the intestinal tract, and vaginal tract (teens and older). The development of candidal disease is generally not transferred from a host to a non-colonized recipient (with the exception of the newborn infant); rather, the development of symptoms and signs represents an overgrowth of the yeast for a number of potential reasons that are reviewed above.
When Should Someone Seek Medical Care for Oral Thrush?
Medical care should be sought when thrush is suspected in a child outside of the infant age range when over-the-counter remedies (see below) are not helpful, or if the infection is painful (maternal breast involvement—for example, cracking or bleeding of the nipple).
A healthcare professional should evaluate all teens and adults with thrush.
How Do Healthcare Professionals Diagnose Oral Thrush?
The diagnosis of oral thrush generally does not require laboratory testing—visual inspection of the mouth is all that is necessary to confirm the diagnosis.
What Is the Incubation Period for Oral Thrush?
The time between birth through a Candida-infected vaginal canal and the development of oral thrush is approximately seven to 10 days. This is the only case of transmission from an infected host to a non-colonized individual. Past the neonatal period, the development of candidal disease reflects an overgrowth of already present Candida yeast colonies.
What Healthcare Specialists Treat Oral Thrush?
Primary care providers (pediatricians, family practice, and internal medicine physicians) are all trained in the diagnosis and treatment of oral thrush.
Older children, teenagers, and adults without an obvious cause to develop oral thrush (for example, improper technique using inhaled corticosteroids) should have a thorough evaluation by a healthcare professional since there are several serious conditions that may predispose to the development of oral thrush (for example, weakened immune system).
What Are Medications and Treatments for Oral Thrush?
Two broad categories of treatments exist to treat oral thrush—a traditional medical approach and a homeopathic approach. Traditional medications may either be topically applied (for example, nystatin, 1% gentian violet) or ingested in liquid form (for example, fluconazole [Diflucan]).
Nystatin is generally applied 4 times a day for approximately 5-7 days. One study (treating HIV/AIDS patients) demonstrated a cure rate of 52% (vs. 87% when employing fluconazole; the immune-compromised status of the study population may have affected outcomes). When treating infants and toddlers, the application using a small gauze or Q-tip is more effective than just drinking the preparation. Most pediatricians will elect topical nystatin in lieu of oral medications for ease of administration, reserving the use of fluconazole for treatment failures; 1% gentian violet is rarely used due to the long-lasting bright purple stain it makes in the mouth or on clothing/bed linen.
Fluconazole is a once-a-day preparation that is used for 14 days. Primary side effects are few (5% or less) and generally intestinal in nature (upset stomach, vomiting, and/or diarrhea). It is rare that such side effects necessitate the discontinuation of the medication. Relapse rates (return of symptoms after apparently successful therapy) are less with fluconazole when compared to nystatin.
Regardless of which approach is used, the application of the medication to baby bottle nipples, pacifiers, or the nipples of breastfeeding mothers is felt to increase the rate of success of therapy by lessening the likelihood of reintroduction of Candida to the infant.
What Are Home Remedies for Oral Thrush?
Nontraditional/homeopathic remedies to treat thrush include:
- Swabbing the mouth area with pure, virgin coconut oil (caprylic acid is the active ingredient)
- Yogurt swabs of the oral area and application to the mother's nipples
- Application of white distilled vinegar and/or a dilute baking soda (1 tsp/8 oz water) to the mother's nipples
- Application of acidophilus to infant oral-involved areas and maternal nipples
- Application of a dilute concentration of apple cider vinegar, tea tree oil, or essential oils to the involved areas
These approaches have not been rigorously and scientifically studied and are recommendations based on anecdotal reports.
How Can People Prevent Oral Thrush?
Since an oral thrush infection generally represents an overgrowth of the yeast Candida albicans that is commonly found in the oral cavity, prevention strategies focus on limiting such overgrowth and limiting repeated reexposure to Candida.
Nursing mothers should avoid damp or wet nursing pads and consider air-drying their nipples if they or their infant develop repeated yeast infections. Similarly, soap and water hygiene for bottle nipples and pacifiers will lessen oral candidiasis. For those needing daily-inhaled corticosteroids for effective asthma control, use of a spacer when using a metered-dose inhaler (MDI) and rinsing and spitting out with water following MDI or nebulizer administered corticosteroids is imperative.
What Is the Prognosis for Oral Thrush?
The prognosis for infants who experience thrush is excellent. The function and effectiveness of the immune system mature as an individual pass from infancy to childhood to adulthood. As such, the frequency of thrush diminishes with age.
Older children, teens, and adults who develop thrush (and are not employing inhaled corticosteroids) should have a thorough evaluation by their physician to identify the underlying reason causing them to be prone to oral thrush.
Reviewed on 10/25/2022
Gupta, Aditya, et al. "Fungal Skin Infections." Pediatrics in Review 38.1 January 2017.
Kimberlin, David W., ed. Red Book: 2018 Report of the Committee on Infectious Diseases, 31st Edition. United States: American Academy of Pediatrics, 2018.
United States. Centers for Disease Control and Prevention. "Oropharyngeal/Esophageal Candidiasis ('Thrush')." Feb. 13, 2014. <http://www.cdc.gov/fungal/diseases/candidiasis/thrush/>.