Thrush (Oral Candidiasis)
A Candida yeast infection of the mouth and throat
Quick Facts
- Type: Fungal (yeast) infection
- Cause: Candida overgrowth, usually Candida albicans
- Hallmark: Creamy white patches in the mouth
- Common in: Infants, older adults, weakened immunity
Overview
Thrush, or oral candidiasis, is an infection caused by an overgrowth of a yeast called Candida, most often Candida albicans. Small amounts of Candida normally live in the mouth, digestive tract, and skin without causing problems. When the balance of microbes is disrupted or the immune system is weakened, the yeast can multiply and cause infection.
Thrush is most common in babies, older adults, people who wear dentures, and those with weakened immune systems. It is usually not serious in otherwise healthy people and responds well to antifungal treatment, but in people with compromised immunity it can spread further down the throat and require closer attention.
Symptoms
The classic sign is creamy white, slightly raised patches in the mouth. Other features include:
- White or yellowish patches on the tongue, inner cheeks, gums, tonsils, or roof of the mouth
- Redness, soreness, or a burning feeling that can make eating and swallowing uncomfortable
- A cottony feeling in the mouth or loss of taste
- Cracking and redness at the corners of the mouth (angular cheilitis)
- In infants, fussiness during feeding and possible white patches that do not wipe away easily
Wiping the white patches may leave a red, sometimes slightly bleeding surface. If the infection spreads to the esophagus, swallowing may become painful or feel obstructed, which needs prompt medical care.
Causes
Thrush develops when something tips the balance in favor of Candida overgrowth. Common triggers include:
- Antibiotics: They can reduce the helpful bacteria that normally keep yeast in check.
- Inhaled corticosteroids: Asthma and COPD inhalers can leave steroid residue in the mouth that encourages yeast.
- Dry mouth: Reduced saliva from medications or medical conditions allows yeast to flourish.
- Weakened immunity: Diabetes, HIV, cancer treatment, and immune-suppressing drugs all increase risk.
- Dentures: Poorly fitting or unclean dentures create a hospitable environment for Candida.
Risk Factors
- Infancy and older age
- Diabetes, especially when blood sugar is poorly controlled
- A weakened immune system from HIV, chemotherapy, or immunosuppressant medication
- Recent or long-term antibiotic use
- Use of inhaled steroids without rinsing the mouth afterward
- Smoking and wearing dentures
- Dry mouth
Diagnosis
A doctor or dentist can often diagnose thrush simply by examining the mouth, since the white patches and underlying redness are characteristic. Additional steps may include:
- Scraping a sample: Gently scraping a patch to view the yeast under a microscope or send for a fungal culture.
- Throat or esophagus exam: If swallowing is painful, an endoscopy may be done to check whether the infection extends into the esophagus.
- Testing for underlying causes: Checking for diabetes or other conditions if thrush keeps coming back.
Treatment
Thrush is treated with antifungal medication, with the choice depending on severity and the person's health:
- Topical antifungals: Nystatin liquid "swish and swallow" or clotrimazole lozenges are used for mild cases.
- Oral antifungal tablets: Fluconazole is often prescribed for more extensive infection or for people with weakened immunity.
- Treating the cause: Rinsing the mouth after steroid inhalers, improving denture hygiene, and controlling blood sugar help clear the infection and prevent recurrence.
Most cases improve within a week or two of starting treatment. Recurrent or severe thrush should prompt a search for an underlying condition.
Prevention
- Rinse your mouth with water (and spit it out) after using an inhaled corticosteroid, or use a spacer device
- Brush your teeth and tongue twice daily and clean dentures every night
- Remove dentures while sleeping and have their fit checked
- Keep blood sugar well controlled if you have diabetes
- Stay hydrated and treat dry mouth
- Avoid smoking
When to See a Doctor
See a doctor or dentist if you have white patches in your mouth that do not clear, if eating becomes painful, or if thrush keeps returning. Seek prompt care if you:
- Have a weakened immune system and develop oral thrush
- Have pain or difficulty swallowing, which can signal spread to the esophagus
- Are caring for an infant who refuses to feed
People with HIV, cancer treatment, or other immune-weakening conditions should be evaluated quickly, as infection can spread more readily.
Frequently Asked Questions
What causes thrush in the mouth?
Thrush is caused by overgrowth of Candida yeast that normally lives harmlessly in the mouth. It tends to appear when something disrupts the balance, such as antibiotics, inhaled steroids, dry mouth, diabetes, or a weakened immune system. Babies and older adults are especially prone.
Is oral thrush contagious?
Thrush is generally not considered contagious in the usual sense, since Candida is already present in most people. However, the yeast can pass between a breastfeeding mother and baby, and people with weakened immunity are more susceptible to developing an infection.
How is thrush treated?
Mild thrush is treated with topical antifungals such as nystatin rinse or clotrimazole lozenges, while more extensive infection may need oral fluconazole tablets. Treating the underlying cause, such as rinsing after steroid inhalers or improving denture care, helps prevent it from returning.
How can I prevent oral thrush from inhalers?
Rinse your mouth with water and spit it out after each use of an inhaled corticosteroid, and consider using a spacer device. Good oral hygiene and regular dental care also reduce the risk. These steps remove steroid residue that would otherwise encourage yeast growth.
When is thrush serious?
In healthy people thrush is usually mild and easily treated. It is more concerning in those with weakened immune systems, where it can spread into the esophagus and cause painful swallowing. Painful or difficult swallowing, or recurrent thrush, should be evaluated by a doctor.
References
- Centers for Disease Control and Prevention (CDC). Candidiasis (Candida infection).
- Mayo Clinic. Oral thrush — Symptoms and causes.
- MedlinePlus, U.S. National Library of Medicine. Thrush.
- National Health Service (NHS). Oral thrush (mouth thrush).