Vaginal Candidiasis: What It Is, What It Is Not, and the Fluconazole Doses That Differ by Severity
Candida lives in the vagina of a large proportion of healthy women without causing anything. It becomes an infection when the balance shifts: protective lactobacilli fall, the environment becomes more hospitable, and the yeast changes form, growing filaments that invade the surface layer of the lining. That invasion, rather than the yeast itself, produces the itch.
About three quarters of women have at least one episode. The condition is straightforward when it is a first, isolated event. Where it goes wrong is in two places: assuming that itching means thrush, and treating recurrence with the same single tablet over and over.
🔍 Only about a third of women who diagnose themselves with thrush actually have it. Studies comparing self-diagnosis against laboratory testing find the majority are wrong, most often because the real cause is bacterial vaginosis, an irritant reaction, or a skin condition of the vulva. Repeatedly buying an antifungal for something that is not fungal delays the correct diagnosis, and the antifungal cream itself can become an irritant. A first episode, and any episode that does not settle, is worth confirming rather than guessing.
🔎 What it looks like, and what it is confused with
| Thrush | Bacterial vaginosis | Irritant reaction | Atrophy after menopause | |
|---|---|---|---|---|
| Main symptom | Itching, often intense | Odour | Burning and stinging | Dryness and soreness |
| Discharge | Thick, white, curd-like, no odour | Thin, grey-white, fishy, worse after sex | Little or none | Little or none |
| Vulval appearance | Red, swollen, sometimes small splits in the skin | Usually normal | Red, sometimes with a rash edge | Pale, thin, loss of elasticity |
| Pain on sex | Yes, superficial | Uncommon | Yes | Yes, with dryness |
| Clue | Itch dominates everything | Odour dominates; itching minimal | Started after a new soap, pad, gel or wipe | Gradual, with urinary symptoms too |
Trichomoniasis is the other one worth excluding, since it causes yellow-green discharge with soreness and is sexually transmitted; our guide to trichomoniasis covers it.
⚠️ The condition most often mistaken for recurrent thrush for years. Lichen sclerosus causes chronic vulval itching, worst at night, with skin that becomes pale, thin and crinkled like tissue paper, and over time the normal architecture is lost and splits appear. It is treated with a potent topical steroid, not an antifungal, and untreated it causes permanent scarring and carries a small risk of vulval cancer.
Anyone whose vulval itching has persisted for months, keeps returning despite antifungals, or comes with pale or thickened skin needs examination by a clinician who will actually look at the vulva. Repeated antifungal courses with no lasting effect is the pattern that should trigger that referral.
🧩 What tips the balance
- Antibiotics
- The commonest trigger. They reduce lactobacilli and leave the yeast unopposed, so an episode a week or two after a course is typical.
- Diabetes and high blood glucose
- A strong driver, and recurrent thrush is sometimes the presenting sign of undiagnosed type 2 diabetes. Worth a glucose or HbA1c check where episodes are frequent.
- Hormones
- Higher oestrogen increases glycogen in the vaginal lining, which favours yeast. Hence more episodes in pregnancy, before periods, and on higher-dose hormonal contraception. It is uncommon after menopause unless the woman is on oestrogen or has diabetes.
- Corticosteroids and immunosuppression
- Including inhaled and oral steroids, and immune-suppressing treatment.
- Moisture and occlusion
- Staying in wet swimwear or gym clothing, and heavy panty liner use. Underwear fabric matters less than how long damp fabric stays in contact.
- Irritants
- Scented washes, wipes, bubble bath, douching. These both cause symptoms directly and damage the flora that keeps yeast in check.
📊 Uncomplicated or complicated: this decides the dose
The distinction is not cosmetic. It is the reason a single tablet works for one woman and fails for another.
| Category | Definition | Treatment |
|---|---|---|
| Uncomplicated | Sporadic, mild to moderate, C. albicans, healthy non-pregnant woman | Fluconazole 150 mg as a single dose, or a short topical course |
| Severe | Marked swelling, redness, skin splitting, excoriation | Fluconazole 150 mg repeated after 72 hours, or 7 to 14 days of topical treatment |
| Recurrent | Four or more episodes in twelve months | Induction, then 150 mg weekly for 6 months |
| Non-albicans | Usually C. glabrata; often milder, poor response to azoles | Boric acid or nystatin; fluconazole frequently ineffective |
| Pregnancy | Any severity | Topical only, for 7 days. Oral fluconazole avoided |
| Diabetes or immunosuppression | Any severity | Treated as complicated, with longer courses |
💊 Fluconazole in practice
Diflucan (Fluconazole) and the generic Fluconaz (Fluconazole) block an enzyme the fungus needs to build its cell membrane. Taken by mouth it reaches the vaginal tissue in high concentration and stays there for days, which is why one tablet can be enough.
- 💊 150 mg as a single dose for an uncomplicated episode, with or without food
- ⏳ Symptoms improve over 24 to 48 hours and can take up to a week to settle fully. Itching that is better but not gone at day three is normal and not a treatment failure
- 🔁 For a severe episode, a second 150 mg dose 72 hours after the first
- 📅 For recurrent disease: three doses of 150 mg given 72 hours apart as induction, then 150 mg once weekly for six months. This suppresses episodes in the large majority of women while it is taken; around half relapse after stopping, which is expected rather than a failure and is why the underlying triggers are addressed in parallel
- 🙂 Side effects are usually mild — headache, nausea, abdominal discomfort. A single dose is very well tolerated
🤰 Oral fluconazole is avoided in pregnancy. High-dose fluconazole causes a recognised pattern of birth defects, and studies of even single low doses have found signals for miscarriage and for cardiac malformation. Thrush is common in pregnancy and it is treated — with a topical azole for seven days, using an applicator gently rather than forcefully. Anyone who might be pregnant should say so before taking a fluconazole tablet, and anyone who took one before realising should mention it at their next appointment rather than panicking, since the absolute risk from a single dose is small.
💊 Interactions worth knowing, mostly for repeated dosing. Fluconazole raises the effect of warfarin, increases levels of simvastatin and atorvastatin with a risk of muscle damage, and prolongs the QT interval, so it is combined cautiously with other QT-prolonging drugs. A single 150 mg dose carries little of this; the six-month weekly regimen carries it all, and the full medication list should be reviewed before starting one.
🧫 When fluconazole does not work
Failure to respond means one of four things, and they are checked in this order.
- It is not thrush. By far the commonest explanation. Bacterial vaginosis, an irritant dermatitis, lichen sclerosus or lichen planus
- It is not C. albicans. Candida glabrata accounts for most non-albicans cases, is intrinsically much less sensitive to fluconazole, and causes milder but stubborn symptoms. It requires a culture to identify, and a different drug
- The trigger is still operating. Uncontrolled glucose, a repeated antibiotic course, ongoing irritant exposure
- The course was too short for the severity
For confirmed C. glabrata, the usual treatment is boric acid 600 mg as a vaginal capsule nightly for 14 days, or nystatin pessaries. Boric acid is effective and it is never taken by mouth, where it is toxic, and it is not used in pregnancy. Where azoles are still considered, itraconazole, available as Sporanox (Itraconazole), is sometimes used under specialist direction.
🌟 Comfort while it settles
- 🧴 Wash with water or a plain emollient only. No soap, shower gel, feminine wash, wipes or bubble bath on the vulva, during the episode and ideally afterwards too
- 🧊 A cool pack wrapped in cloth, or a cool bath without additives, for the itching
- 🚫 Do not scratch — splits in the skin sting on urinating and take longer to heal than the infection
- 💧 Pass urine before applying anything, and pat dry rather than rubbing
- 👕 Loose clothing and no panty liners while inflamed
- 🛏️ Nothing overnight, including underwear, if the itching is worst at night
- 💊 A barrier ointment before urinating protects split skin
❌ What does not help
Medical Disclaimer: The information in this article is for educational and informational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek guidance from a qualified healthcare provider with any questions you may have regarding a medical condition, and before starting, stopping or changing any medication.