Oral candidiasis, also called oral thrush, is a fungal infection of the mouth caused mainly by Candida albicans. Candida species are part of the normal oral microbiota, but under specific conditions they can shift from harmless colonizers to pathogenic organisms capable of invading oral tissues. This infection can appear on the tongue, inner cheeks, palate, or gums. It may also involve the corners of the mouth, leading to angular cheilitis.
The infection can occur in individuals of all ages, but it is more frequent in infants, older adults, people using inhaled corticosteroids, denture wearers, and those with weakened immune systems. Oral candidiasis is generally not dangerous in healthy people, but it can cause discomfort.
Why Does Oral Candidiasis Occur?
The transition of Candida from a commensal organism to a pathogen occurs when the host's protective mechanisms are disrupted. Several factors contribute to this imbalance. Reduced salivary flow, whether due to medications or medical conditions, decreases the natural cleansing effect of saliva. Antibiotic use can disrupt the balance of oral bacteria that normally keep fungal growth in check.
Immune suppression is a central factor. Conditions such as HIV infection, diabetes mellitus, malignancies, and therapies like chemotherapy or high-dose corticosteroids weaken the body's ability to control fungal colonization. Researchers have also shown that denture use, especially when dentures are worn at night, creates an environment with reduced oxygen and increased moisture, which supports fungal proliferation.
Lifestyle factors such as smoking and poor oral hygiene may increase risk. High-carbohydrate diets can influence fungal metabolism and adherence to oral tissues. The presence of biofilms on dental appliances further protects Candida from natural immune responses. When these combined influences are present, fungal cells multiply excessively and invade superficial epithelial layers.
How Does Oral Candidiasis Present Clinically?
Oral candidiasis may present in several forms that differ in appearance and symptoms. The most recognized form is pseudomembranous candidiasis, characterized by white, creamy plaques on oral surfaces. These plaques can be wiped away, leaving red or slightly bleeding mucosa. Patients often report a burning sensation, altered taste, or mild mouth soreness.
Another form, erythematous candidiasis, appears as red, inflamed patches, often on the palate or tongue. This type may occur after antibiotic use or in denture wearers. Chronic hyperplastic candidiasis is less common and presents as white plaques that cannot be removed through scraping. Angular cheilitis involves cracking at the corners of the mouth, often combined with saliva pooling and secondary infection.
Infants may show fussiness, difficulty feeding, and white patches on the tongue or cheeks. Adults may experience discomfort during swallowing if the infection spreads down the throat. In immunocompromised patients, oral candidiasis can be more persistent and may progress to esophageal involvement.
Can A Dermatoscope Assist in Detecting Oral Candidiasis?
When a dermatoscope is used on mucosal surfaces it can reveal features that are consistent with oral candidiasis, so it can be used as an adjunct to help recognise the infection.
• White, yellow-white or grey-white structureless areas
• Bright-red eroded zones where papillae are lost and vessels are exposed, together with dotted (and a few linear) blood vessels
A dermatoscope can help visualize features suggestive of oral candidiasis, but it cannot independently confirm the diagnosis. Diagnosis still relies on clinical examination, response to therapy, and—when needed—laboratory testing such as KOH smear, fungal culture, or cytology.
How Is Oral Candidiasis Treated?
Treatment depends on the severity of the infection and the patient's overall health. For mild cases, topical antifungal medications are the first choice. These may include nystatin oral suspension or clotrimazole troches. They act locally and generally cause few systemic effects.
For moderate to severe cases, or when topical treatment is ineffective, systemic antifungal medications may be used. Fluconazole is commonly prescribed due to its predictable absorption and effectiveness. In cases where resistance is present or fluconazole cannot be used, alternatives such as itraconazole or posaconazole may be considered.
Dentures should be cleaned thoroughly, and antifungal agents may be applied to their surfaces. Denture wearers are advised to avoid wearing them overnight. For individuals using inhaled corticosteroids, proper inhaler technique and rinsing the mouth after use can significantly reduce the risk of recurrence.
Can Oral Candidiasis Be Prevented?
Prevention focuses on reducing risk factors. Regular oral hygiene practices, including toothbrushing and cleaning of dental appliances, play an important role. Denture wearers should ensure proper fit and avoid wearing dentures during sleep.
For individuals taking inhaled corticosteroids, rinsing the mouth thoroughly after each use helps reduce fungal growth. Good control of underlying conditions such as diabetes is also crucial. Avoiding smoking and limiting high-sugar foods can reduce risk as well.
People with dry mouth can benefit from adequate hydration and saliva-stimulating strategies. Maintaining balanced oral microbiota through consistent hygiene is important for long-term prevention.