Yeast infection (vaginal) - Causes, Treatment & When to See a Doctor

What is Yeast infection (vaginal)?

A vaginal yeast infection, also called Candida vaginitis or candidiasis, is an over‑growth of the fungus Candida (most often C. albicans) in the vaginal canal. The normal vagina hosts a balanced mix of bacteria and fungi; when the balance is disrupted, yeast can multiply rapidly, leading to inflammation and the classic symptoms of itching, burning, and abnormal discharge.

Yeast infections are very common—~75% of women will experience at least one episode in their lifetime ^[1]. They are usually not sexually transmitted, although sexual activity can sometimes trigger an episode by altering the vaginal environment.

Common Causes

Several factors can upset the delicate vaginal ecosystem and allow yeast to proliferate:

• Antibiotic use – Broad‑spectrum antibiotics kill beneficial lactobacilli that keep Candida in check.
• High‑dose or prolonged corticosteroid therapy – Systemic steroids suppress immunity.
• Uncontrolled diabetes mellitus – Elevated blood glucose provides a food source for yeast.
• Hormonal changes – Pregnancy, oral contraceptives, or hormone replacement therapy increase estrogen, which favors yeast growth.
• Poor glycemic control in the diet – Frequent consumption of sugary foods can promote Candida overgrowth.
• Moist, warm environments – Tight clothing, non‑breathable underwear, or staying in wet swimwear for prolonged periods.
• Immunosuppression – HIV infection, chemotherapy, or organ transplantation.
• Use of irritant feminine products – Scented soaps, douches, or feminine hygiene sprays can disrupt the natural pH.
• Recent vaginal surgery or device use – Catheters, intrauterine devices (IUDs), or contraceptive rings.
• Stress – Chronic stress can weaken local immune defenses.

Associated Symptoms

While each woman’s experience can differ, the following signs are most frequently reported alongside a yeast infection:

• Intense itching or burning, especially around the vulva and inner thighs.
• Thick, white “cottage‑cheese” discharge that does not have a strong odor.
• Redness, swelling, and a feeling of soreness in the vaginal area.
• Dyspareunia – pain or discomfort during sexual intercourse.
• Burning sensation during urination (often due to irritation of the urethral opening).
• Occasional spotting or light bleeding after intercourse.

When to See a Doctor

Most uncomplicated cases can be treated at home with over‑the‑counter (OTC) antifungals, but medical evaluation is important when any of the following occur:

• Symptoms persist after 3–4 days of OTC therapy.
• First episode of vaginal symptoms—diagnosis is needed to rule out other infections.
• Recurrent infections (four or more episodes per year).
• Severe itching, swelling, or pain that interferes with daily activities.
• Presence of a fever, chills, or abdominal pain.
• Painful urination accompanied by a strong odor or green/yellow discharge (possible bacterial infection).
• Pregnancy – even mild symptoms should be evaluated because some treatments are contraindicated.

Diagnosis

Healthcare providers usually follow a step‑wise approach:

1. Medical History & Physical Exam

The clinician will ask about symptom onset, sexual activity, medication use, diabetes status, and hygiene practices. A visual inspection of the vulva and vagina may reveal erythema, edema, or characteristic discharge.

2. Microscopic Examination (Wet Mount)

A sample of vaginal discharge is placed on a slide with saline or potassium hydroxide (KOH). Under a microscope, budding yeast cells or pseudohyphae confirm candidiasis.

3. Vaginal pH Testing

Yeast infections typically have a normal vaginal pH (3.8–4.5). A pH >4.5 suggests bacterial vaginosis or trichomoniasis, prompting different treatment.

4. Culture or PCR (Rarely Needed)

If the diagnosis is uncertain, a culture can identify the specific Candida species and any drug resistance. This is especially useful in recurrent or refractory cases.

Treatment Options

Treatment focuses on eliminating the overgrowth, relieving symptoms, and preventing recurrence.

1. Over‑the‑Counter Antifungal Creams/Ointments

• Miconazole (Monistat) – 1% cream, 3‑day or 7‑day regimen.
• Clotrimazole (Gyne‑Lotrimin) – 1% cream, 7‑day course.
• Terbinafine (Lamisil) – 1% cream, 7 days.

2. Prescription‑only Oral Antifungals

• Fluconazole (Diflucan) – Single 150 mg tablet for uncomplicated cases; repeat dosing for recurrent infections.
• Itraconazole – Occasionally used for resistant strains.

3. Prescription Topical Agents

• Butoconazole (Vagistat‑1) – 2% vaginal cream, 7‑day treatment.
• Econazole (Gynazole) – 1% vaginal suppositories.

4. Home & Lifestyle Measures

• Wear breathable cotton underwear; avoid tight leggings or synthetic fabrics.
• Change out of wet clothing (e.g., swimsuits, gym gear) promptly.
• Limit sugary foods and refined carbohydrates.
• Use gentle, unscented cleansers; avoid douching.
• Probiotic‑rich foods (yogurt with live cultures) or a daily probiotic supplement may help restore lactobacilli.

5. Management of Recurrent Infections

For women with ≥4 episodes per year:

• Extended‑duration oral fluconazole (once weekly for 6 months) plus a short‑course after each subsequent episode.
• Topical azole regimen (e.g., clotrimazole 2% cream nightly for 6 months).
• Address underlying risk factors—optimise diabetes control, review antibiotic usage, evaluate estrogen therapy.

Prevention Tips

While occasional yeast infections are normal, the following strategies reduce the likelihood of recurrence:

• Maintain a healthy vaginal pH – Avoid scented tampons, pads, and feminine sprays.
• Practice good glycemic control if you have diabetes.
• Choose breathable clothing – Cotton underwear, loose‑fitting pants.
• Limit prolonged antibiotic courses – Use them only when prescribed and complete the full course.
• Stay dry – After bathing, pat the genital area dry, especially the skin folds.
• Urinate after sexual activity to flush potential irritants.
• Use water‑based lubricants if needed; avoid oil‑based products that can promote fungal growth.
• Consider probiotic supplementation (Lactobacillus rhamnosus GR‑1 & Lactobacillus reuteri RC‑14 have some evidence) after discussing with a clinician.

Emergency Warning Signs

References

• 1. Mayo Clinic. Vaginal yeast infection (candidiasis). https://www.mayoclinic.org/diseases‑conditions/vaginal‑yeast‑infection/diagnosis‑treatment
• 2. Centers for Disease Control and Prevention (CDC). Yeast Infections. https://www.cdc.gov/fungal/diseases/candidiasis/index.html
• 3. National Institutes of Health (NIH) – Office of Disease Prevention. Candida Infections. https://www.niaid.nih.gov/diseases‑conditions/candidiasis
• 4. Cleveland Clinic. Vaginal Yeast Infections: Causes, Symptoms, Treatment. https://my.clevelandclinic.org/health/diseases/14557‑vaginal‑yeast‑infection
• 5. World Health Organization (WHO). Guidelines for the treatment of fungal infections. 2023.