Candidiasis: Symptoms, Causes, Testing, and Treatment

Candida is a genus of fungi comprising over 150 species, with the most common pathogenic types being Candida albicans, Candida glabrata, Candida tropicalis, and Candida parapsilosis. Under normal conditions, small amounts of Candida exist on the skin, in the gastrointestinal tract, the vagina, and the mouth, without causing any harm. However, when the balance of the microbial flora is disrupted or the immune defenses are weakened, Candida can overgrow and cause an infection known as candidiasis.

Candida infections range from superficial forms such as oral thrush and vaginal candidiasis to more serious and systemic conditions like invasive or bloodstream candidiasis, which can be life-threatening if not promptly treated. Accurate diagnosis and understanding of the underlying causes are critical for effective disease management, particularly within the scope of Functional Medicine, which investigates not just symptoms, but also deeper biological mechanisms and interactions.

Diagnostiki Athinon, through specialized Functional Medicine testing, provides the necessary tools for in-depth evaluation of the body's microbial health and metabolic balance, offering a personalized approach to managing fungal overgrowth.

Epidemiological Data

Candida albicans is the most frequent cause of fungal infections in humans, responsible for approximately 70% of candidiasis cases. Candida infections vary from mild to life-threatening, depending on the site of infection, the species involved, and the host’s immune status.Αccording to global epidemiological data:

• Approximately 75% of women will experience at least one episode of vaginal candidiasis in their lifetime.
• In 5–10% of these cases, the condition will be recurrent (≥4 episodes per year).
• Oral candidiasis is more commonly observed in infants, the elderly, and immunocompromised individuals.
• Systemic Candida infections are often recorded in intensive care units and among patients with cancer, organ transplants, or HIV/AIDS.

In Greece, epidemiological data remain limited. However, studies from major hospitals confirm that Candida albicans continues to dominate, while infections from non-albicans species are increasing, especially in hospitalized patients. This rise is associated with the extensive use of antibiotics, immunosuppressants, and intravenous catheters. The emergence of resistant strains, such as Candida auris, represents a serious public health concern worldwide, due to the challenges in identification and their resistance to multiple antifungal drugs.

Symptoms and Signs of Candidiasis

The mere presence of Candida in the human body does not imply illness. However, when it overgrows, it can lead to a broad spectrum of symptoms depending on the area affected and the individual's overall health. Candida manifestations are classified as either superficial or systemic.

Oral Candidiasis

• Symptoms: Painful white plaques on the inner cheeks, tongue, or throat, possibly accompanied by a burning sensation, difficulty swallowing, or loss of taste.
• At-risk groups: Infants, elderly individuals, denture wearers, users of inhaled corticosteroids, people with diabetes, or those with suppressed immunity.

Vaginal Candidiasis

• Symptoms: Itching, redness, pain or burning during intercourse or urination, and thick white discharge resembling cottage cheese.
• Recurrent form: Defined as ≥4 episodes within 12 months, often without an obvious trigger.

Cutaneous Candidiasis

• Symptoms: Red, moist lesions with white plaques and peripheral scaling. Typically found in skin folds such as between fingers, underarms, or beneath the breasts.
• Contributing factors include Obesity, excessive sweating, poor hygiene, and antibiotic use.

Genital Candidiasis in Men

• Symptoms: Redness, itching, or irritation of the glans and foreskin, with or without discharge. Often follows sexual contact with a woman with vaginal candidiasis.

Gastrointestinal Candidiasis

• Symptoms: Bloating, gas, intermittent diarrhea or constipation, incomplete digestion, cravings for carbohydrates or sugar.
• This is a less-studied form, but of growing interest within the scope of functional medicine.

Systemic Candidiasis (Invasive or Bloodstream)

• Symptoms: Fever unresponsive to antibiotics, hypotension, respiratory distress, and altered mental status. Organs like the lungs, liver, spleen, or brain may be affected.
• Typically affects: ICU patients, transplant recipients, cancer patients, individuals with neutropenia, or those on prolonged antibiotic therapy.

Non-specific and Subacute Symptoms (in chronic Candida overgrowth)

• Chronic fatigue, mental "fog", poor concentration
• Mood or sleep disturbances
• Skin conditions (acne, eczema, allergies)
• Food or alcohol intolerances

These non-specific symptoms are often difficult to attribute to Candida without a comprehensive laboratory evaluation.

Underlying Causes of Candidiasis

Candida overgrowth is not a random phenomenon but rather the result of imbalances within the body that normally would restrict its proliferation. Functional Medicine, focusing on root causes rather than mere symptoms, helps restore the internal balance that prevents Candida from dominating. The following factors contribute significantly to the pathogenesis and recurrence of candidiasis:

1. Dysbiosis of the Gut Microbiome
A healthy intestinal flora limits the growth of Candida by competing for nutrients and producing antifungal substances. The use of broad-spectrum antibiotics, a diet low in fiber and high in sugars, and chronic stress can all disrupt the microbiome, allowing Candida to thrive.

2. High Intake of Sugars and Simple Carbohydrates
Candida uses glucose as its primary energy source. Diets rich in sugar, sweeteners, and refined carbohydrates create an ideal environment for rapid fungal growth in the gut and mucous membranes.

3. Immune System Suppression
Immunosuppression due to diseases (e.g., HIV, cancer) or medication (e.g., corticosteroids, immunosuppressants) diminishes the body’s ability to control Candida. Additionally, chronic sleep deprivation, stress, and poor nutrition negatively affect immune function.

4. Hormonal Imbalances
Fluctuations in estrogen levels, such as during pregnancy, oral contraceptive use, or hormone replacement therapy, are associated with increased risk of vaginal candidiasis. Estrogens influence pH balance and the composition of vaginal epithelium, fostering a more hospitable environment for Candida.

5. Chronic Inflammation and Intestinal Permeability ("Leaky Gut")
Candida may contribute to increased permeability of the intestinal wall, allowing toxins and allergens to enter the bloodstream. This condition enhances the inflammatory response and is linked to a wide range of chronic conditions such as irritable bowel syndrome, autoimmune diseases, and skin disorders.

6. Environmental and Chemical Stressors
The accumulation of heavy metals (especially mercury and cadmium), exposure to mold toxins, pesticides, or endocrine-disrupting chemicals can impair immune function and increase susceptibility to Candida colonization.

Laboratory Testing for Disease Investigation

The diagnostic approach to candidiasis should not rely solely on symptoms. Laboratory confirmation is a critical step toward personalized treatment, especially when Candida may be concealed behind chronic or recurrent issues. Testing is divided into conventional, functional, and imaging categories.

(a) Conventional Laboratory Tests
Conventional tests are widely used in primary or hospital care settings. These include:

• Stool Culture: Enables the identification of Candida species present in the gut. While useful in acute cases, it has limited sensitivity in chronic subclinical forms.
• Swab Culture (oral, vaginal, or skin): A basic method for confirming localized infections, allowing for fungal species identification.
• Candida Antigen Detection (β-D-Glucan): A molecular method that detects fungal cell wall antigens in the bloodstream. Particularly useful for diagnosing systemic mycosis.
• Complete Blood Count (CBC), C-reactive protein (CRP), and inflammation markers: Although non-specific, they are essential for assessing the patient’s general condition, especially in febrile illness or suspected sepsis.

(b) Functional Medicine Testing
Functional Medicine tests aim to evaluate the body as an integrated biological system. They are especially valuable in chronic, recurrent, or non-specific Candida-related cases. Specifically:

• EnteroScan® – Gut Microbiome Testing: A comprehensive stool analysis that assesses bacterial and fungal flora, the presence of yeasts (like Candida), inflammation, digestive residue, and pathogens.
• MetaBolomiX® – Urinary Organic Acids Test: By analyzing specific metabolites (such as arabinose), this test can indirectly detect the presence of Candida. It also evaluates metabolic function, gut health, and mitochondrial performance.
• Candida IgG/IgA/IgM: A serological test for antibodies against Candida. Elevated IgG may suggest past exposure, while IgA or IgM presence indicates possible active infection or recent contact with the pathogen.
• Intestinal Permeability Testing: Assesses the "leakiness" of the gut wall. Increased intestinal permeability is usually a result of long-term Candida overgrowth.
• TrophoScan® – IgG Food Intolerance Testing: Identifies delayed immune reactions to foods that may sustain inflammation and promote fungal overgrowth.
• ImmuneScan® – Immune Function Evaluation: Assesses immune system function, particularly in individuals with recurrent infections. It includes analysis of immune cell subpopulations and immunoglobulin levels.
• SIBO Breath Test (Small Intestinal Bacterial Overgrowth): Although focused on bacterial overgrowth, it is closely associated with Candida development, as both often coexist. Fermentation of sugars by gut microbes produces gases detectable in exhaled breath.

(c) Other Examinations

• Abdominal Ultrasound: Used to detect possible abscesses or organ lesions when systemic candidiasis is suspected.
• CT or MRI Scan: Recommended when infection is suspected in deep tissues or organs (e.g., brain, liver).

Therapeutic Approaches for Candidiasis

The treatment of candidiasis depends on the site and severity of the infection, as well as the presence or absence of underlying disorders. A comprehensive approach includes both pharmaceutical interventions and lifestyle or dietary modifications, particularly in chronic or recurrent forms.

(a) Conventional Treatments

• Nystatin: A topical or oral medication mainly used for mild intestinal or oral infections. It is not absorbed from the gastrointestinal tract.
• Fluconazole: A commonly prescribed drug for oral, vaginal, and systemic candidiasis. Treatment may require 7–14 days of continuous dosing. In chronic cases, it may be administered periodically.
• Itraconazole, Voriconazole: Reserved for more severe or drug-resistant forms of the disease.
• Amphotericin B: A potent antifungal agent used for serious systemic infections, usually administered intravenously. It carries a high risk of nephrotoxicity.
• Topical Care: Includes mouth rinses, probiotic washes, wearing loose-fitting clothing, and proper hygiene in cases of skin or vaginal candidiasis.
• Addressing Underlying Factors: Involves controlling diabetes, discontinuing unnecessary antibiotic use, and monitoring hormone levels.

Pharmaceutical treatment is effective at suppressing fungal overgrowth, but it does not address the deeper causes that promote Candida proliferation. Therefore, a holistic strategy is often required.

(b) Natural Therapies
Natural therapies aim to restore microbial balance and disrupt the internal environment that supports Candida overgrowth. Particular emphasis is placed on diet, detoxification, herbal remedies, and immune support.

Diet: The “anti-Candida” diet is based on eliminating foods that promote fungal growth and enhancing those that inhibit it:

• Eliminated: Sugar, refined flours, white rice, processed juices, alcohol, yeast, mushrooms, and industrial food products.
• Emphasized: High-quality proteins, leafy green vegetables, antimicrobial foods (garlic, onion, ginger), flaxseeds, coconut oil (rich in caprylic acid), and adequate hydration.
• Timing: The strict diet phase typically lasts 4–6 weeks, followed by gradual food reintroduction under supervision.

Lifestyle: Chronic immune stress increases vulnerability to Candida. Therefore, the following are recommended:

• Adequate sleep and rest: At least 7–8 hours per night.
• Daily physical activity: Supports detoxification and gut regulation.
• Stress management: Through mindfulness, meditation, yoga, or psychological support.

Supplements and Herbal Remedies

• Probiotics: Contain Lactobacillus and Bifidobacterium strains, which compete with Candida. Taken once or twice daily, ideally 30 minutes before meals. Typical dosage ranges from 10–50 billion CFUs per day.
• Caprylic Acid: A fatty acid derived from coconut oil with strong antifungal activity. Dosage: 500–1000 mg, 2–3 times daily with meals. Contraindicated in individuals with liver issues.
• Grapefruit Seed Extract: A powerful natural antifungal. Usually taken as drops (10–15 in water, 2–3 times/day).
• Antifungal Herbs: Oregano (essential oil), thyme, pau d’arco, cinnamon. Oregano, for example, has proven efficacy against Candida but requires careful dosing (1–2 drops diluted in oil, not taken directly in the mouth).
• Garlic (Allicin): A natural antifungal and antibacterial agent. Can be used raw or as a supplement.
• Intestinal Binders and Cleansers: Such as activated charcoal or bentonite clay, which bind toxins released during Candida die-off and reduce treatment-related reactions (Herxheimer reaction).

References

1. Pappas, P. G., Kauffman, C. A., Andes, D. R., et al. (2023). Clinical Practice Guideline for the Management of Candidiasis: 2023 Update by the Infectious Diseases Society of America. Clinical Infectious Diseases, 76(1), e1–e50.
2. Bertuccio, F. R., Baio, N., Montini, S., et al. (2025). Pulmonary Infiltrates in a Non-Cystic Fibrosis Bronchiectasis Patient: A Case Report. Journal of Clinical Medicine, 14(16), 5914.
3. Zhang, Y., Ma, Y., Yue, R., et al. (2025). Meningitis caused by Aspergillus fumigatus: A case report. BMC Infectious Diseases, 25(1), 457.
4. Jo, H. J., Kim, M. J., Lee, H. A., et al. (2025). Detection of Fusarium solani using cutinase antibody and its application in diagnosing fungal keratitis in an animal model. PLOS ONE, 20(8), e0330455.
5. Copeland, D. C., Mott, B. M., Kortenkamp, O. L., et al. (2025). Image-based honey bee larval viral and bacterial diagnosis using machine learning. Scientific Reports, 15, 16261.
6. Chen, M. H., Cai, Z., Cui, W., et al. (2025). Rhizopus arrhizus Causing Scalp Mucormycosis in a Young Type 1 Diabetic Patient. Mycopathologia, 190(2), 124–131.
7. Ghosal, D., Sarkar, R., Tikadar, P., et al. (2025). Molecular characterization of pectin lyase and endopolygalacturonase from Fusarium commune. Physiological and Molecular Plant Pathology, 122, 102159.
8. Chen, Y., Wu, X., Xu, C., et al. (2025). Pathogen virulence genes: Advances and challenges. International Journal of Molecular Medicine, 56(3), 5614.
9. Amerson-Brown, M. H. (2025). Identifying the complexities of clinical diagnostics for vaginal infections. Microbiology Spectrum, 13(4), e00251-25.
10. Rafałowicz, J., Wagner, L. (2025). Lesions on the tongue after SARS-CoV-2 infection: A retrospective study. Dental and Medical Problems, 62(2), 117–125.