Among individuals being treated in intensive care units, the mortality rate is about 30-50% when systemic candidiasis develops.

The diagnosis can typically be made from the clinical appearance alone, but not always. As candidiasis can be variable in appearance, and present with white, red or combined white and red lesions, the differential diagnosis can be extensive. In pseudomembraneous candidiasis, the membranous slough can be wiped away to reveal an erythematous surface underneath. This is helpful in distinguishing pseudomembraneous candidiasis from other white lesions in the mouth that cannot be wiped away, such as lichen planus, oral hairy leukoplakia. Erythematous candidiasis can mimic geographic tongue. Erythematous candidiasis usually has a diffuse border that helps distinguish it from erythroplakia, which normally has a sharply defined border.

Special investigations to detect the presence of candida species include oral swabs, oral rinse or oral smears. Smears are collected by gentle scraping of the lesion with a spatula or tongue blade and the resulting debris directly applied to a glass slide. Oral swabs are taken if culture is required. Some recommend that swabs be taken from 3 different oral sites. Oral rinse involves rinsing the mouth with phosphate-buffered saline for 1 minute and then spitting the solution into a vessel that examined in a pathology laboratory. Oral rinse technique can distinguish between commensal candidal carriage and candidiasis. If candidal leukoplakia is suspected, a biopsy may be indicated. Smears and biopsies are usually stained with periodic acid-Schiff, which stains carbohydrates in fungal cell walls in magenta. Gram staining is also used as Candida stains are strongly Gram positive.

Sometimes an underlying medical condition is sought, and this may include blood tests for full blood count and hematinics.

If a biopsy is taken, the histopathologic appearance can be variable depending upon the clinical type of candidiasis. Pseudomembranous candidiasis shows hyperplastic epithelium with a superficial parakeratotic desquamating (i.e., separating) layer. Hyphae penetrate to the depth of the stratum spinosum, and appear as weakly basophilic structures. Polymorphonuclear cells also infiltrate the epithelium, and chronic inflammatory cells infiltrate the lamina propria.

Atrophic candidiasis appears as thin, atrophic epithelium, which is non-keratinized. Hyphae are sparse, and inflammatory cell infiltration of the epithelium and the lamina propria. In essence, atrophic candidiasis appears like pseudomembranous candidiasis without the superficial desquamating layer.

Hyperplastic candidiasis is variable. Usually there is hyperplastic and acanthotic epithelium with parakeratosis. There is an inflammatory cell infiltrate and hyphae are visible. Unlike other forms of candidiasis, hyperplastic candidiasis may show dysplasia.

A diet that supports the immune system and is not high in simple carbohydrates contributes to a healthy balance of the oral and intestinal flora. While yeast infections are associated with diabetes, the level of blood sugar control may not affect the risk. Wearing cotton underwear may help to reduce the risk of developing skin and vaginal yeast infections, along with not wearing wet clothes for long periods of time.

Oral hygiene can help prevent oral candidiasis when people have a weakened immune system. For people undergoing cancer treatment, chlorhexidine mouthwash can prevent or reduce thrush. People who use inhaled corticosteroids can reduce the risk of developing oral candidiasis by rinsing the mouth with water or mouthwash after using the inhaler.

For women who experience recurrent yeast infections, there is limited evidence that oral or intravaginal probiotics help to prevent future infections. This includes either as pills or as yogurt.

The severity of oral candidiasis is subject to great variability from one person to another and in the same person from one occasion to the next. The prognosis of such infection is usually excellent after the application of topical or systemic treatments. However, oral candidiasis can be recurrent. Individuals continue to be at risk of the condition if underlying factors such as reduced salivary flow rate or immunosuppression are not rectifiable.

Candidiasis can be a marker for underlying disease, so the overall prognosis may also be dependent upon this. For example, a transient erythematous candidiasis that developed after antiobiotic therapy usually resolves after antibiotics are stopped (but not always immediately), and therefore carries an excellent prognosis—but candidiasis may occasionally be a herald of a more sinister undiagnosed pathology, such as HIV/AIDS or leukemia.

It is possible for candidiasis to spread to/from the mouth, from sites such as the pharynx, esophagus, lungs, liver, anogenital region, skin or the nails. The spread of oral candidiasis to other sites usually occurs in debilitated individuals. It is also possible that candidiasis is spread by sexual contact. Rarely, a superficial candidal infection such as oral candidiasis can cause invasive candidiasis, and even prove fatal. The observation that Candida species are normally harmless commensals on the one hand, but are also occasionally capable of causing fatal invasive candidiases has led to the description "Dr Jekyll and Mr Hyde".

The role of thrush in the hospital and ventilated patients is not entirely clear however there is a theoretical risk of positive interaction of candida with topical bacteria that could increase the risk for Ventilator Associated Pneumonia and other diseases.

The diagnosis is usually made based upon the clinical appearance, and swabs can be taken of the surface of the denture. Investigations to rule out possibility of diabetes may be indicated. Tissue biopsy is not usually indicated, but if taken shows histologic evidence of proliferative or degenerative responses and reduced keratinization and epithelial atrophy.

In most cases the diagnosis is established based on response to therapy. Patients in whom esophageal candidiasis is suspected should receive a brief course of antifungal therapy with fluconazole. If the infection resolves after treatment with fluconazole, then the diagnosis of esophageal candidiasis is made and no further investigation is needed. However, if the infection persists or if there are other factors involved which may warrant further investigation, then patient will undergo an esophagogastroduodenoscopy if it is safe to do so. Endoscopy often reveals classic diffuse raised plaques that characteristically can be removed from the mucosa by the endsocope. Brushing or biopsy of the plaques shows yeast and pseudohyphae by histology that are characteristic of "Candida" species.

Angular chielitis is normally a diagnosis made clinically. If the sore is unilateral, rather than bilateral, this suggests a local factor ("e.g.", trauma) or a split syphilitic papule. Angular cheilitis caused by mandibular overclosure, drooling, and other irritants is usually bilateral.

The lesions are normally swabbed to detect if Candida or pathogenic bacterial species may be present. Persons with angular cheilitis who wear dentures often also will have their denture swabbed in addition. A complete blood count (full blood count) may be indicated, including assessment of the levels of iron, ferritin, vitamin B12 (and possibly other B vitamins), and folate.

Angular cheilitis could be considered to be a type of cheilitis or stomatitis. Where Candida species are involved, angular cheilitis is classed as a type of oral candidiasis, specifically a primary (group I) Candida-associated lesion. This form angular cheilitis which is caused by Candida is sometimes termed "Candida-associated angular cheilitis", or less commonly, "monilial perlèche". Angular cheilitis can also be classified as acute (sudden, short-lived appearance of the condition) or chronic (lasts a long time or keeps returning), or refractory (the condition persists despite attempts to treat it).

The current first-line treatment is fluconazole, 200 mg. on the first day, followed by daily dosing of 100 mg. for at least 21 days total. Treatment should continue for 14 days after relief of symptoms.

Other therapy options include:

- nystatin is not an effective treatment for esophageal candidiasis. It can be used as (swish, do not swallow) treatment for oral candidiasis that occurs with the use of asthma pumps.

- other oral triazoles, such as itraconazole

- caspofungin, used in refractory or systemic cases

- amphotericin, used in refractory or systemic cases

The most important aspect of treatment is improving denture hygiene, i.e. removing the denture at night, cleaning and disinfecting it, and storing it overnight in an antiseptic solution. This is important as the denture is usually infected with "C. albicans" which will cause re-infection if it is not removed. Substances which are used include solutions of alkaline peroxides, alkaline hypochlorites (e.g. hypochlorite, which may over time corrode metal components of dental appliances), acids (e.g. benzoic acid), yeast lytic enzymes and proteolytic enzymes (e.g. alcalase protease). The other aspect of treatment involves resolution of the mucosal infection, for which topical antifungal medications are used (e.g. nystatin, amphotericin, miconazole, fluconazole or itraconazole). Often an antimicrobial mouthwash such as chlorhexidine is concurrently prescribed. Possible underlying disease (diabetes, HIV) should be treated where possible.

Chronic mucocutaneous candidiasis can be diagnosed in an affected individual via the following methods/tests:

Because many "Candida" species are part of the human microbiota, their presence in the mouth, the vagina, sputum, urine, stool, or skin is not definitive evidence for invasive candidiasis.

Positive culture of "Candida" species from normally sterile sites, such as blood, cerebrospinal fluid, pericardium, pericardial fluid, or biopsied tissue, is definitive evidence of invasive candidiasis. Diagnosis by culturing allows subsequent susceptibility testing of causitive species. Sensitivity of blood culture is far from ideal, with a sensitivity reported to be between 21 and 71%. Additionally, whereas blood culture can establish a diagnosis during fungemia, the blood may test negative for deep-seated infections because candida may have been successfully cleared from the blood.

Diagnosis of invasive candidiasis is supported by histopathologic evidence (for example, yeast cells or hyphae) observed in specimens of affected tissues.

Additionally, elevated serum β-glucan can demonstrate invasive candidiasis while a negative test suggests a low likelihood of systemic infection.

The emergence of multidrug-resistant "C. auris" as a cause of invasive candidiasis has necessitated additional testing in some settings. "C. auris"-caused invasive candidiasis is associated with high mortality. Many "C. auris" isolates have been found to be resistant to one or more of the three major antifungal classes (azoles, echinocandins, and polyenes) with some resistant to all three classes - severely limiting treatment options. Biochemical-based tests currently used in many laboratories to identify fungi, including API 20C AUX and VITEK-2, cannot differentiate "C. auris" from related species (for example, "C. auris" can be identified as "C. haemulonii"). Therefore, the Centers for Disease Control and Prevention recommends using a diagnostic method based on matrix-assisted laser desorption/ionization-time of flight mass spectrometry or a molecular method based on sequencing the D1-D2 region of the 28s rDNA to identify "C. auris" in settings were it may be present.

About 5-8% of the reproductive age female population will have four or more episodes of symptomatic Candida infection per year; this condition is called recurrent vulvovaginal candidiasis (RVVC). Because vaginal and gut colonization with Candida is commonly seen in people with no recurrent symptoms, recurrent symptomatic infections are not simply due to the presence of Candida organisms. There is some support for the theory that RVVC results from an especially intense inflammatory reaction to colonization. Candida antigens can be presented to antigen presenting cells, which may trigger cytokine production and activate lymphocytes and neutrophils that then cause inflammation and edema.

Preventative antifungal treatment is supported by studies, but only for specific high-risk groups in intensive care units with conditions that put them at high risk for the disease. For example, one group would be patients recovering from abdominal surgery that may have gastrointestinal perforations or anastomotic leakage. Antifungal prophylaxis can reduce the incidence of fungemia by approximately 50%, but has not been shown to improve survival. A major challenge limiting the number of patients receiving prophylaxis to only those that can potentially benefit, thereby avoiding the creation of selective pressure that can lead to the emergence of resistance.

Vulvovaginal candidosis is the presence of "Candida" in addition to vaginal inflammation. The presence of yeast is typically diagnosed in one of three ways: vaginal wet mount microscopy, microbial culture, and antigen tests. The results may be described as being either uncomplicated or complicated.

Management for an individual with chronic mucocutaneous candidiasis consists of the following(relapse occurs once treatment is ceased, in many cases):

Chronic ulcerative stomatitis is a recently discovered condition with specific immunopathologic features. It is characterized by erosions and ulcerations which relapse and remit. Lesions are located on the buccal mucosa (inside of the cheeks) or on the gingiva (gums). The condition resembles Oral lichen planus when biopsied.

The diagnosis is made with Immunofluorescence techniques, which shows circulating and tissue-bound autoantibodies (particulate stratified squamous-epithelium-specific antinuclear antibody) to DeltaNp63alpha protein, a normal component of the epithelium. Treatment is with hydroxychloroquine.

The diagnosis is usually made on the clinical appearance, and tissue biopsy is not usually needed. The histologic picture is one of superficial candidal hyphal infiltration and a polymorphonuclear leukocytic inflammatory infiltrate present in the epithelium. The rete ridges are elongated and hyperplastic (pseudoepitheliomatous hyperplasia, which may be mistaken for carcinoma).

Otomycosis is treated by debridment followed with topical azole antifungals, and symptomatically managed with oral antihistamines. Per a study in Iran 10cc acetic acid 2% plus 90 cc of isopropyl alcohol 70% was effective.

To avoid misdiagnosis as nail psoriasis, lichen planus, contact dermatitis, nail bed tumors such as melanoma, trauma, or yellow nail syndrome, laboratory confirmation may be necessary. The three main approaches are potassium hydroxide smear, culture and histology. This involves microscopic examination and culture of nail scrapings or clippings. Recent results indicate the most sensitive diagnostic approaches are direct smear combined with histological examination, and nail plate biopsy using periodic acid-Schiff stain. To reliably identify nondermatophyte molds, several samples may be necessary.

There are four classic types of onychomycosis:

- Distal subungual onychomycosis is the most common form of "tinea unguium" and is usually caused by "Trichophyton rubrum", which invades the nail bed and the underside of the nail plate.

- White superficial onychomycosis (WSO) is caused by fungal invasion of the superficial layers of the nail plate to form "white islands" on the plate. It accounts for around 10 percent of onychomycosis cases. In some cases, WSO is a misdiagnosis of "keratin granulations" which are not a fungus, but a reaction to nail polish that can cause the nails to have a chalky white appearance. A laboratory test should be performed to confirm.

- Proximal subungual onychomycosis is fungal penetration of the newly formed nail plate through the proximal nail fold. It is the least common form of "tinea unguium" in healthy people, but is found more commonly when the patient is immunocompromised.

- Candidal onychomycosis is "Candida" species invasion of the fingernails, usually occurring in persons who frequently immerse their hands in water. This normally requires the prior damage of the nail by infection or trauma.

Hygiene, in particular the regular cleaning of the glans, is generally considered sufficient to prevent infection and inflammation of the foreskin. Full retraction of the foreskin may not be possible in boys younger than about ten years and some may not be able to fully retract their foreskin for cleaning until their late teens.

Terms such as "plasma cell gingivostomatitis", "atypical gingivostomatitis" and "idiopathic gingivostomatitis" are sometimes a synonym for plasma cell gingivitis, or specifically to refer to a severe form of plasma cell gingivitis.

Diagnosis is typically suspected based on a women's symptoms. Diagnosis is made with microscopy (mostly by vaginal wet mount) and culture of the discharge after a careful history and physical examination have been completed. The color, consistency, acidity, and other characteristics of the discharge may be predictive of the causative agent. Determining the agent is especially important because women may have more than one infection, or have symptoms that overlap those of another infection, which dictates different treatment processes to cure the infection. For example, women often self-diagnose for yeast infections but due to the 89% misdiagnosis rate, self-diagnoses of vaginal infections are highly discouraged.

Another type of vaginitis, called desquamative inflammatory vaginitis (DIV) also exists. The cause behind this type is still poorly understood. DIV corresponds to the severe forms of aerobic vaginitis. About 5 to 10% of women are affected by aerobic vaginitis.

The International Statistical Classification of Diseases and Related Health Problems codes for the several causes of vaginitis are:

Prevention of candidiasis, the most common type of vaginitis, includes using loose cotton underwear. The vaginal area should be washed with water. Perfumed soaps, shower gels, and vaginal deodorants should be avoided. Douching is not recommended. The practice upsets the normal balance of yeast in the vagina and does more harm than good.

Prevention of bacterial vaginosis includes healthy diets and behaviors as well as minimizing stress as all these factors can affect the pH balance of the vagina.

Prevention of trichomoniasis revolves around avoiding other people's wet towels and hot tubs, and safe-sex procedures, such as condom use.

Some women consume good bacteria in food with live culture, such as yogurt, sauerkraut and kimchi, or in probiotic supplements either to try to prevent candidiasis, or to reduce the likelihood of developing bacterial vaginitis following antibiotic treatment. There is no firm evidence to suggest that eating live yogurt or taking probiotic supplements will prevent candidiasis.

Studies have suggested a possible clinical role for the use of standardized oral or vaginal probiotics in the treatment of bacterial vaginosis, either in addition to or in place of the typical antibiotic regimens. However, recent articles question their efficacy in preventing recurrence compared with other means, or conclude that there is insufficient evidence for or against recommending probiotics for the treatment of bacterial vaginosis.