On history taking, patients will often complain of patchy white lesions on the tongue and/or buccal mucosa. 

Additionally, it is crucial to elicit forms of immunosuppression such as smoking, antibiotic and/or steroid use, immunosuppressing drugs in transplant patients, use of dentures, malnutrition, etc.

Clinically, oral candidiasis consists of white pseudomembranous plaques. They are difficult to remove and affect the oral mucosa, tongue, hard, and soft palates. It is usually painless, associated with a loss of taste and angular cheilitis (cracking of the skin at the corner of the patient's mouth).

The plaques are often challenging to scrape off with a tongue blade. After scraping, inflamed, painful lesions often remain that may bleed.

Patients may also have a candidal rash in other regions of their bodies as well. Clinicians need to check for candidal diaper dermatitis as well.

Diagnosis of oral candidiasis is often clinical, based on appearance and risk factors. Additionally, the appearance of an erythematous, inflamed, and bleeding base after scraping off the plaques also leads to a likely oral thrush diagnosis.

For further confirmation, plaques can be cultured. Alternatively, a gram stain of plaques showing large, ovoid, gram-positive yeast is diagnostic. Lastly, pseudohyphae with a potassium hydroxide stain can be visible.

In addition to the confirmation of candidiasis, testing to diagnose an underlying immunocompromising condition is important. Patients should be interviewed, examined, and tested accordingly for diseases such as HIV, adrenal insufficiency, malnutrition, steroid use, and diabetes. 

Treatment focuses on Candida species. It should be targeted to the extent of the involvement and degree of immunosuppression of the patient. In general, antifungal agents are the recommended treatment. These treat infection by altering RNA or DNA metabolism or causing intracellular accumulation of peroxide in the fungal cells.

For patients with a mild presentation or having their first presentation of the disease, topical treatment is the recommended therapy. One option is clotrimazole troches 10 mg orally five times daily (dissolved over 20 minutes). Another is nystatin oral suspension (100000 units/mL) 5 mL orally four times daily (swished for several minutes then swallowed).[6][7] In the appropriate circumstances, miconazole oral gel may also be an option.[8]

For moderate to severe disease, fluconazole 200 mg orally once then 100 mg orally once daily for a total of 7 to 14 days is recommended. Data regarding the safety of fluconazole during breastfeeding is reassuring.[9]

For refractory disease, options are Itraconazole oral solution 200 mg once daily without food for 28 days, posaconazole suspension 400 mg orally two times daily for 3 days, then 400 mg orally daily for a total of 28 days and voriconazole 200 mg orally two times daily for 28 days.

Additionally, single-dose oral fluconazole 150 mg has shown to be effective in patients with advanced cancer, thus helping reduce pill burden.[10]

For vaginal candidiasis, several over the counter options are available: clotrimazole 1% cream vaginally for 7 to 14 nights, clotrimazole 2% cream vaginally for 3 nights, miconazole 2% cream vaginally for 7 nights, miconazole 4% cream vaginally for 3 nights, miconazole 100 mg suppository vaginally for 3 nights, tioconazole 6.5% ointment vaginally once. There are also prescription therapies: nystatin 100000-unit vaginal tablet for 14 nights, terconazole 80 mg one suppository vaginally for 3 nights, terconazole 0.8% cream vaginally for 3 nights, butoconazole 2% cream one applicator vaginally once (do not use during the first trimester of pregnancy). Lastly, an oral therapy option is fluconazole 150 mg PO once (may repeat in 72 hours if symptoms persist).

Dosing for these regimens should be adjusted according to weight for pediatric patients.

In addition to treatment, patients should receive counseling on how to decrease immunosuppressing conditions such as uncontrolled diabetes, smoking, and malnutrition. 

When suspecting the diagnosis of oral candidiasis in a patient with oral lesions, a differential diagnosis of oral hairy leukoplakia (a condition triggered by the Ebstein-Barr virus), angioedema, aphthous stomatitis, herpes gingivostomatitis, herpes labialis, measles (Koplik spots), perioral dermatitis, Steven-Johnsons syndrome, histiocytosis, blastomycosis, lymphohistiocytosis, diphtheria, esophagitis, syphilis and streptococcal pharyngitis amongst other conditions must be considered.

The prognosis of a patient with oral thrush often is dependent on his or her degree of immunosuppression. Those that are otherwise immunocompetent will often achieve resolution of the disease and symptoms. Those that are immunocompromised often need concomitant treatment of their immunosuppressing condition to fully recover.

Although unlikely in an immunocompetent host, oral candidiasis can lead to pharyngeal involvement. Symptomatically, this can lead to dysphagia and respiratory distress.

A significant concern for immunocompromised patients is the systemic dissemination of the disease.

Candidal esophagitis is a particularly common complication of oral candidiasis in those with HIV/AIDS.

Patients with oral thrush should receive counseling regarding the future spread of the disease. They also need to understand the importance of diagnosing and treating any immunosuppressing conditions.

One of the most critical educational pearls regarding the diagnosis and treatment of candidal thrush is clinical suspicion. A healthcare provider must take a thorough history to know when a patient has an immunocompromising condition. Knowing this can lead to the healthcare provider evaluating for thrush in the first place and being aware of the possibility of other, potentially life-threatening, systemic infections.

Oral candidiasis is a diagnosis that is important to make. Patients usually have white and/or gray patches in their oral mucosa. They may also have systemic manifestations of their immunocompromised state. Examples of these are dysphagia secondary to pharyngeal candidiasis, failure to thrive, and sepsis. Case management for the majority of these patients will be by the primary care provider, nurse practitioner, and obstetrician.

Since the diagnosis and treatment of oral candidiasis have several important implications for the patient, healthcare professionals must work together. Registered nurses, physician assistants, nurse practitioners, and physicians must collaborate both in triage and diagnostic areas to correctly diagnose oral thrush. Pathologists may be involved to assess culture and stain oral scrapings. Depending on the underlying immunosuppressing condition, oncologists and infectious disease specialists may provide consult. As oral candidiasis is often the first sign of a significant systemic immunocompromising condition, the hand-off from the primary healthcare provider to see the patient to the specialists that will continue to monitor their chronic illness is very important. The pharmacist should educate the patient on the importance of medication compliance, as well as well as verifying medication dosing and checking for drug-drug interactions, and reporting any concerns to the healthcare team. Patients with diabetes should be urged to monitor their blood sugar levels. Also, the patient should receive instruction to quit smoking. Patients who take inhaled steroids should be asked to perform water gargles after each use and follow up with the clinician. Nursing will administer medications for inpatients and provide significant counseling to reinforce the points above. Only with an interprofessional collaborative team approach can candidiasis treatment achieve optimal patient results. [Level V]

Lastly, it is imperative that healthcare providers treating those susceptible to oral candidiasis be aware of the utility of preventive strategies. For example, via randomized controlled trials, probiotics, for example, have been shown to prevent oral candidiasis in the elderly.