Candidiasis Explained: Types, Signs, and How It’s Treated

Medically Reviewed by Dr. Rae Osborn, Ph.D.

Candidiasis, a fungal infection, is caused by the overgrowth of Candida species, most often Candida albicans, a type of yeast. Candida organisms naturally live in parts of the body, including the mouth, throat, intestines, vagina, and even on the skin. Under normal conditions, they remain harmless when balanced with healthy bacteria and immune defenses. However, when these fungi multiply excessively, they can cause localized infections, such as oral thrush, vaginal yeast infection, or cutaneous candidiasis. In more severe cases, they may progress to life-threatening systemic disease. Thus, candidiasis is often described as a fungal infection that arises when natural defenses are compromised.

Globally, candidiasis is considered one of the most common fungal infections. According to recent epidemiological studies, recurrent vulvovaginal candidiasis (VVC) affects nearly 138 million women annually, with about 75% of women experiencing at least one episode in their lifetime. Oral candidiasis remains the most common fungal infection of the mouth and throat.

What Causes Candidiasis?

Normal Presence of Candida in the Body

Candidiasis is not always a sign of poor hygiene or infection. The human body naturally hosts Candida species, especially Candida albicans, as part of its normal flora. These fungi live in the mouth, throat, intestines, vagina, and skin without causing symptoms. In healthy individuals, the growth of Candida is controlled by friendly bacteria (such as Lactobacillus, in the vagina) and a functioning immune system.

However, when this balance is disturbed, Candida may overgrow and invade surrounding tissues, leading to localized infections or, in severe cases, systemic candidiasis.

Primary Causes and Risk Factors for Candidiasis

The main cause of candidiasis is the overgrowth of Candida albicans. The factors contributing to this condition can include the following:²

• Weakened Immune System, due to HIV/AIDS, TB, Myxoedema, Addison's disease, nutritional deficiencies, cancer therapy, or organ transplantation.

• Disrupted Body Microbiome, often after prolonged use of antibiotics or corticosteroids, which can reduce protective bacteria.
• Hormonal fluctuations, such as during pregnancy, due to menopause, or when using birth control pills, may increase vaginal yeast infection risk.
• Uncontrolled blood sugar levels, especially in diabetes, create an ideal environment for fungal growth.

Other risk factors include

• Excessive moisture in skin folds, leading to cutaneous candidiasis.
• Low birth weight or prematurity in infants (predisposing them to diaper rash or oral thrush).
• Poorly fitted dentures, poor oral hygiene, or dryness of mouth (xerostomia).
• Hospitalization and invasive medical devices like catheters and IV lines (raising the risk of invasive candidiasis).

Link Between Candidiasis and Psoriasis

Candidiasis is a fungal infection, whereas psoriasis is a chronic autoimmune inflammatory skin disease in which the immune system mistakenly attacks healthy skin cells. Although they are distinct conditions, research suggests a possible link between the two. Individuals with psoriasis often show increased colonization of Candida species, particularly in the skin, oral cavity, and intestines. Certain Candida species can trigger cytokine production by the immune system, which can induce psoriasis flares. Furthermore, the use of immunosuppressive agents or topical corticosteroids in the management of psoriasis may increase susceptibility to candidiasis.

Types of Candidiasis

Candidiasis is not a single disease but rather a spectrum of fungal infections that affect different parts of the body. Symptoms may include itching, burning, redness, white patches, or systemic illness, depending on the site of the infection and severity. The various clinical types of candidiasis are given below:

Oral Candidiasis

Commonly called thrush, this candidiasis is the most recognizable form of fungal infection. More than 90% of individuals with HIV experience at least one episode of oral thrush during their lifetime. Besides HIV, weakened immune defences, particularly in infants, older adults, and immunocompromised individuals (e.g., those with chronic conditions such as diabetes, hypothyroidism, or hypoparathyroidism), can be a risk factor. Nutritional deficiencies (iron, folic acid, zinc, vitamin B12, and vitamin C) can further compromise immunity and increase susceptibility to fungal infections. The use of inhaled corticosteroids for asthma or COPD without rinsing the mouth afterward is another possible causative factor. Wearing dentures or orthodontic appliances (braces) that are not cleaned regularly can increase the risk, creating a breeding ground for fungi. Dry mouth (xerostomia), often caused by medications or aging, reduces the presence of protective antifungal proteins (e.g., histatin, calprotectin) in saliva, which can lead to oral candidiasis. Other potential causes include smoking and alcohol consumption, which can disrupt the balance of oral flora.

Symptoms

The most common oral candidiasis symptoms include:

• White, creamy plaques on the tongue, inner cheeks, throat, or palate that may be easily wiped off, leaving a red base.
• Burning sensation in the mouth or throat.
• Cracks at the corners of the mouth (angular cheilitis).
• Difficulty swallowing or pain when eating.
• In severe cases, it spreads to the esophagus (esophageal candidiasis), causing chest pain and difficulty swallowing.

Variants

• Pseudomembranous candidiasis – the typical form, showing creamy white patches that can be scraped away.

• Atrophic candidiasis – often seen under dentures, with red, sore tissue.

• Candidiasis of the oesophagus – extends into the food pipe, leading to pain on swallowing (odynophagia). This is often a sign of immunosuppression like HIV/AIDS.

Prevalence

The condition is more common in:

• Infants (due to immature immunity, birth canal exposure).
• Older adults (especially denture wearers).
• Hospitalized patients and those with HIV/AIDS, diabetes, or cancer.

Differential diagnosis

• Oral Candidiasis vs Leukoplakia – The clinical appearance of oral candidiasis can resemble several other oral pathologies. Leukoplakia presents as white plaques that cannot be wiped off and often carry precancerous potential, whereas pseudomembranous candidiasis lesions are removable but leave an erythematous base.

• Erythroplakia, Lichen Planus, Pemphigus – Erythroplakia and oral lichen planus cause red or erosive patches but lack fungal hyphae under microscopy. Pemphigus vulgaris and mucous membrane pemphigoid may present with mucosal erosions but typically include blister formation.

• Oral Hairy Leukoplakia – It is caused by the Epstein-Barr virus (EBV) and seen mostly in patients with HIV. While oral hairy leukoplakia is not responsive to antifungal therapy, the treatment may be used if there is a co-occurring Candida infection. Therefore, microscopy or culture confirmation is important for diagnosis.

Vaginal Candidiasis

Commonly called a vaginal yeast infection, vaginal candidiasis is caused by the overgrowth of Candida albicans in the vaginal mucosa.⁷

Symptoms

The most common vaginal candidiasis symptoms include:

• Severe vaginal itching and irritation.
• Thick, white, “cottage cheese-like” discharge.
• Redness, burning, and pain during urination or sex.
• In recurrent cases, symptoms may be more intense (severe yeast infection symptoms).

Prevalence

Around 75% of women experience at least one episode in their lifetime, and 40–45% have recurrent infections. The risk increases with antibiotic use, pregnancy, diabetes, and oral contraceptives. It is more common in:

• Women of reproductive age.
• Pregnant women.
• Women on birth control pills, antibiotics, or immunosuppressive therapy.

Differential diagnosis

• Bacterial Vaginosis vs Trichomoniasis vs Candidiasis – The symptoms of vulvovaginal candidiasis often overlap with other vaginal infections. Bacterial vaginosis typically causes a thin, grayish discharge with a distinct fishy odor and lacks the intense itching seen in yeast infections. Trichomoniasis, caused by Trichomonas vaginalis, presents with a frothy green-yellow discharge and may show motile protozoa on microscopy.

• Dermatitis or STIs – Contact dermatitis or allergic vaginitis can mimic redness and irritation but occur after exposure to soaps, spermicides, or hygiene products. Sexually transmitted infections, such as chlamydia and gonorrhea, may also cause discomfort and discharge but are distinguished via NAAT testing.

Cutaneous Candidiasis

It refers to the infections affecting the skin surfaces, such as the umbilicus, groin, under the breasts, nails, and moist areas.

Symptoms

The most common cutaneous candidiasis symptoms include:

• Red, itchy, beefy-looking rash.
• Satellite pustules (small pus-filled blisters) or vesicles (small clear fluid-filled blisters) around the main rash.
• Scaling, fissures, and discomfort.
• Commonly mistaken for other skin infections.

Variants

• Intertriginous candidiasis: In body folds (groin, under breasts).
• Candidiasis navel: Infection in the umbilical region.
• Candidiasis on lips/cheilitis: Painful cracks at the corners of the mouth.

Differential diagnosis

• Candidiasis vs Tinea Cruris – Tinea cruris (jock itch) is a dermatophyte infection characterized by dry scaling edges with central clearing, unlike the beefy-red lesions with satellite pustules seen in candidiasis.
• Candidiasis vs Dermatophytosis – Dermatophytosis affects the keratinized areas, such as the scalp and nails, whereas Candida favors mucocutaneous folds.
• Superficial Candidiasis vs Tinea Versicolor – Pityriasis (tinea) versicolor, caused by Malassezia species, manifests as hypo or hyperpigmented macules without the erythematous inflammation of candidiasis.
• Inverse Psoriasis – Inverse psoriasis is an autoimmune condition that can appear in body folds as red, shiny lesions, but it lacks satellite pustules.

Invasive/Systemic Candidiasis

While less common, invasive candidiasis is the most dangerous form of the disease. It occurs when Candida enters the bloodstream (candidemia) or internal organs.

Symptoms

The most common systemic candidiasis symptoms include:

• Persistent fever and chills unresponsive to antibiotics.
• Low blood pressure due to sepsis.
• Organ-specific symptoms (e.g., kidney dysfunction, endophthalmitis).

Prevalence

This condition is common in:

• Hospitalized patients in ICUs.
• Individuals with weakened immune systems.
• Patients with central venous catheters, prolonged antibiotics, or parenteral nutrition.

Differential diagnosis

• Candidiasis vs Candidemia – Candidemia is specifically Candida in the bloodstream, confirmed by positive blood cultures. Invasive candidiasis is broader and includes candidemia or deep-seated tissue/organ infection (hepatosplenic, endocarditis, peritonitis) that may be culture-negative. Work-up typically combines serial blood cultures, fungal biomarkers such as 1,3-β-D-glucan, targeted imaging, ophthalmic exam, and sometimes PCR. High-risk ICU patients not improving on antibiotics often warrant empiric echinocandin therapy while diagnostics proceed.
• Sepsis from Bacterial Infections – This is often difficult to distinguish. Both can present with fever, hypotension, and organ dysfunction, but clues to Candida include broad-spectrum antibiotic exposure, central venous catheters, TPN, recent abdominal surgery/leaks, neutropenia, or prolonged ICU stay. Bacterial cultures are often positive in bacterial sepsis; in invasive candidiasis, they may be negative while 1,3-β-D-glucan is elevated. Procalcitonin tends to be higher in bacterial sepsis (not definitive).

Other Forms of Candidiasis

• Diaper Candidiasis: It is a common concern among parents. While diaper rash can be irritant or allergic in nature, diaper candidiasis typically presents as a red rash with satellite lesions and may affect infants, particularly those younger than 1 year, with low birth weight or frequent antibiotic exposure.
• Nail Candidiasis (a form of Onychomycosis): This form involves nail candidiasis, where nails become thick, brittle, and discolored. It may accompany mucocutaneous (mucous membrane and skin-related) or systemic disease.
• Intertriginous candidiasis: It occurs in skin folds where friction and moisture are common, e.g., under the breasts or groin.
• Candidiasis of the intestinal tract: It is associated with Candida overgrowth and yeast infection in the gut, leading to bloating, diarrhea, or abdominal pain as the microbiome is disrupted.
• Stomatitis candidiasis: Candida infection of the oral mucosa (skin covering the oral cavity) leading to painful inflammation and ulcers.

Differential Diagnosis – Summary Table

Diagnosis

Candidiasis can mimic several other skin infections, oral lesions, and gynecological conditions, making an accurate diagnosis essential. Since symptoms can vary depending on the affected area, doctors rely on a combination of physical examination, laboratory tests, and imaging when needed.

Physical Examination

It is often the first step. The doctor would look for:

• White patches in the mouth or throat (oral thrush).
• Red, moist rashes with satellite pustules in skin folds (cutaneous candidiasis).
• Thick white vaginal discharge (vaginal yeast infection).

These signs often provide enough evidence for a presumptive diagnosis. However, because candidiasis symptoms can overlap with conditions like bacterial vaginosis, trichomoniasis, leucoplakia, and dermatophytosis, laboratory confirmation is recommended in recurrent or complicated cases.

Swabs, Scrapings, and Culture Tests

• Swab or scraping samples are collected from the affected area (mouth, vagina, skin).
• The specimen is examined under a microscope with potassium hydroxide (KOH) preparation, revealing budding yeast and pseudohyphae.
• Culture tests (e.g., Sabouraud agar, Chromagar Candida) identify the specific Candida species (like Candida albicans, Candida glabrata, Candida auris).
• Cultures are particularly important in recurrent infections or when antifungal resistance is suspected.

Blood Tests and Systemic Evaluation

For invasive or systemic candidiasis, diagnosis often requires:

• Blood cultures to detect candidemia.
• Serological tests (e.g., beta-D-glucan, PCR-based tests) to confirm fungal presence.
• Blood work also helps assess underlying risk factors, like blood sugar levels in diabetes.

Endoscopy or Imaging

• In suspected esophageal candidiasis, endoscopy may reveal white plaques along the esophagus.
• CT or MRI scans may be required if the infection spreads to deep tissues or organs.

How to Treat Candidiasis Infections

The treatment of candidiasis depends on the type of infection, severity, and the patient’s overall health.

Topical Antifungals

These agents are the first-line treatment for mild infections involving the skin, oral cavity, and vaginal mucosa. They are safe, widely available, and usually effective within 1–2 weeks.

• Skin and Cutaneous Candidiasis: Treated with topical creams, lotions, or powders containing clotrimazole, miconazole, or ketoconazole. These agents can help reduce itching, redness, and rash in the affected area.
• Vaginal Yeast Infections: Short courses of intravaginal antifungal creams or pessaries (clotrimazole, miconazole, or nystatin) are effective. These are available in single-dose, 3-day, or 7-day regimens.
• Oral Thrush (Mild Cases): Nystatin suspension (“swish and swallow”) or clotrimazole troches are often prescribed.

Oral Antifungal Medications

These agents are used when topical therapy is ineffective or when infections are more extensive.

• Fluconazole: Commonly prescribed for oral candidiasis, esophageal candidiasis, and recurrent vaginal infections (example: 100 mg daily for 7–14 days).
• Itraconazole and Posaconazole: Effective against non-albicans species and resistant strains.
• Voriconazole: Reserved for severe or resistant cases.

Intravenous (IV) Antifungal Therapy

For invasive candidiasis and hospitalized patients, IV antifungal therapy is often life-saving.

• Echinocandins (caspofungin, micafungin, anidulafungin): First-line for candidemia and invasive candidiasis due to strong efficacy and fewer side effects.
• Amphotericin B: Used in severe or refractory cases, though associated with kidney toxicity.
• Fluconazole IV: Considered in stable patients without resistant species.

The hospitalized patients often require long courses (2–6 weeks) of therapy, along with removal of infected catheters or devices to prevent recurrence.

How to Prevent Candidiasis Infections

Dietary Adjustments

• Consuming a diet rich in whole grains, vegetables, lean proteins, and probiotic fermented foods supports a balanced gut microbiome.
• Foods to avoid include high-sugar items (cakes, sweets, sugary drinks), refined carbohydrates (white bread, pasta), and alcohol, all of which promote fungal growth.
• Reducing yeast-containing foods, such as beer, wine, and certain cheeses, may also help individuals prone to recurrent infections.

Probiotic Use

Probiotics like Lactobacillus and Bifidobacterium aid in restoring healthy bacterial balance in the gut and vaginal flora, naturally suppressing Candida overgrowth. Probiotics can be consumed through:

• Supplements (capsules or powders).
• Fermented products, such as kefir, sauerkraut, yogurt, and kimchi.

Regular probiotic use has been linked to lower recurrence of vaginal yeast infections and oral candidiasis.

Hygiene and Clothing

• Maintain Hygiene. Clean dentures daily and avoid sleeping with them in place, rinse the mouth after inhaled corticosteroids, and wash hands frequently to prevent spreading. Ensure proper oral care through brushing and flossing regularly.
• Keep skin folds dry, especially in humid climates. Powders and breathable fabrics can reduce moisture.
• Wear loose, cotton-based clothing and avoid tight underwear to limit fungal growth in warm, moist areas.

Managing Underlying Conditions

• Diabetes management: Keeping blood sugar under control lowers the risk of recurrent candidiasis.
• Avoid unnecessary antibiotics or steroids: Only use these medications under medical guidance.
• Strengthen immunity: Adequate sleep, balanced nutrition, and exercise help maintain immune defences.

Regular Medical Check-ups

Those with compromised immunity, such as individuals with HIV/AIDS, undergoing cancer therapy, or post–organ transplant, are advised to attend routine medical check-ups. Early monitoring can detect oral thrush, systemic candidiasis, or cutaneous infections before they worsen.

How Is Candidiasis Treated During Pregnancy?

VVC is a common condition during pregnancy due to elevated estrogen and glycogen levels in vaginal secretions. Candida can store glycogen.

Treatment options for candidiasis during pregnancy include:

• Topical azoles (imidazole/triazole): Preferred treatment for 7 days; safe during pregnancy.
• Nystatin: Safe alternative; especially recommended in cases resistant to azole antifungals.
• Clotrimazole (vaginal cream or suppository): Safe in all trimesters; recommended dose is 2% cream or 100 mg suppositories for 7 days, depending on severity.
• Oral fluconazole: A short-term, low dose of 150 mg can be administered as second-line therapy in severe cases.

When to See a Doctor

If There Are Persistent or Recurrent Infections

If you experience recurrent vaginal yeast infections, chronic oral thrush, or skin rashes that keep returning, it may indicate an underlying issue like diabetes, weakened immunity, or antibiotic overuse. Clinical assessment can assist in identifying and treating the root cause.

If Not Responding to OTC Treatments

Most superficial candidiasis responds to topical antifungal medications. However, if symptoms persist beyond 7–10 days despite treatment, a stronger oral or prescription antifungal may be required. Persistent infection can also suggest infection by non-albicans Candida species, which may be resistant to common treatments.

If You Develop Signs of Systemic Infection

Seek immediate medical care if you deal with:

• Fever and chills unresponsive to antibiotics.
• Unexplained fatigue, organ pain, or low blood pressure.
• Difficulty swallowing or chest discomfort (possible esophageal candidiasis).

These symptoms may indicate invasive candidiasis, which is potentially life-threatening and requires urgent hospital-based care with IV antifungal therapy.

If You Are Immunocompromised

Individuals with HIV/AIDS, cancer, organ transplants, or long-term steroid use should be especially cautious. Even mild thrush or skin infections in these groups may progress quickly to systemic candidiasis. Prompt medical evaluation ensures timely treatment and prevents complications.

What Happens If Candidiasis Is Not Treated?

If left untreated, candidiasis may progress to serious complications, including:

• Oral candidiasis: Spreads to the esophagus, causing painful swallowing and malnutrition.
• Vaginal candidiasis: Severe itching, redness, burning, and pain during urination or sex.
• Cutaneous candidiasis: Secondary bacterial skin infections, spreading rashes.
• Nail candidiasis: Permanent nail damage, paronychia (painful swelling around nails).
• Systemic candidiasis: Sepsis, organ failure, and death if untreated.

FAQs

Does candidiasis cause bad breath?

Yes. Oral candidiasis (thrush) can cause bad breath (halitosis) due to fungal overgrowth, inflammation, and breakdown of tissues in the mouth. Good oral hygiene and antifungal treatment usually resolve this symptom.

Does candidiasis cause infertility?

Candidiasis itself does not directly cause infertility. However, recurrent vaginal yeast infections (RVVC) can cause discomfort, pain during intercourse, and inflammation, which may indirectly affect fertility if untreated. Unlike certain STIs, candidiasis is not considered a sexually transmitted disease.

Can candidiasis cause abdominal pain?

Yes, in some cases. Candidiasis of the intestinal tract or systemic candidiasis can cause bloating, cramps, or abdominal discomfort. However, abdominal pain is not a typical feature of mild oral or vaginal candidiasis. Overgrowth in the gut (Candida overgrowth and yeast infection) is also linked to digestive discomfort in some individuals. Persistent abdominal pain should be evaluated to rule out other conditions.

Can candidiasis cause weight loss?

Uncomplicated skin or oral infections do not cause weight loss. However, systemic candidiasis symptoms, such as prolonged fever, fatigue, poor appetite, and digestive involvement, can result in unintended weight loss, especially in hospitalized patients and those with weakened immune systems.

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