Recurrent thrush and BV: telling them apart

Most people who come to us about repeated thrush have already treated it four or five times from a pharmacy. Some of them have thrush. A good number have bacterial vaginosis, a skin condition, or nothing infective at all — and the treatments for those pull in different directions, which is why the pattern of “treat, improve slightly, relapse in three weeks” is so common.

The two conditions are genuinely different. Thrush is an overgrowth of a yeast, usually Candida albicans, and its defining feature is itch. Bacterial vaginosis is a shift in the vaginal bacterial population — the protective lactobacilli thin out and other organisms take their place — and its defining feature is smell, not itch.

That distinction does most of the diagnostic work. It is worth spending a minute on before you buy anything.

Telling them apart

The reason self-diagnosis matters is that it is wrong often enough to change decisions. When researchers have checked women buying over-the-counter antifungals against a swab, only a minority turned out to have thrush alone; the rest had BV, a mixed picture, or a non-infective cause. Being wrong once costs you a wasted week. Being wrong repeatedly means a year of antifungals for a problem antifungals cannot touch — and repeated antifungal exposure is itself a way of selecting for the yeast species that do not respond to them.

If your discharge smells and does not itch, an antifungal is the wrong medicine. If you have used three of them this year and are still symptomatic, the next step is a swab, not a fourth.

What “recurrent” actually means

Recurrent thrush has a definition: four or more symptomatic episodes in twelve months, with at least some confirmed rather than assumed. Recurrent BV is usually taken as three or more in the same period. Both thresholds exist because they mark the point where the sensible approach changes shape.

Below that threshold, treating each episode as it comes is reasonable. Above it, you are no longer dealing with a series of unlucky infections — you are dealing with a system that keeps returning to the same state, and the useful question stops being “what will clear this episode” and becomes “what will hold it clear”. Those need different regimens, different lengths, and a confirmed diagnosis first.

What genuinely drives recurrence

Some causes are worth actively looking for, because addressing them changes the outcome more than any course of treatment.

• Antibiotics. Broad-spectrum antibiotics reduce lactobacilli, which both raises the risk of thrush and destabilises the flora in a way that favours BV. If your episodes reliably follow a course of antibiotics, that is a real pattern, not a coincidence.
• Blood glucose. Poorly controlled diabetes is a well-established driver of recurrent thrush. Recurrent thrush with thirst, weight loss or frequent urination should prompt a glucose check — occasionally the thrush is how the diabetes announces itself.
• Immunosuppression. Oral steroids, immunosuppressant drugs, chemotherapy or untreated HIV all make recurrence more likely and can shift which organism is responsible.
• Oestrogen. Candida favours an oestrogenised vaginal lining, which is why thrush clusters in pregnancy and the reproductive years and is genuinely uncommon after the menopause. Higher-oestrogen contraception and some HRT regimens can play a part — worth discussing when you review contraceptive options rather than assuming.
• Semen exposure. Semen is alkaline. Regular unprotected sex shifts vaginal pH upward, which suits the organisms behind BV. This is why the smell is often worst the morning after sex, and why condom use sometimes reduces recurrence noticeably.
• A new or additional sexual partner, including a new female partner, is one of the more consistent associations with BV. BV is not a sexually transmitted infection, but it behaves as though sexual activity influences it, because it does.
• Smoking is repeatedly associated with BV and with poorer response to treatment. Stopping is one of the few interventions with a plausible effect on the underlying flora.

The things that mostly do not matter

Tight clothing, synthetic underwear, sugar in the diet, swimming pools, and “not being clean enough” are the explanations people arrive with, and the evidence behind them is weak to absent. They are worth naming because they carry blame, and blame leads to the one behaviour that reliably makes things worse.

Why washing more makes bacterial vaginosis worse

BV is a loss of protective bacteria. Douching, internal washing, soaps, shower gels, bubble bath and scented wipes all strip those bacteria and raise pH — precisely the conditions BV needs. Douching in particular is associated with higher, not lower, rates of BV, and there is no clinical situation in which we recommend it.

The same products cause a second problem: contact dermatitis of the vulva, which itches and stings and looks enough like thrush that it is often treated as thrush for months. The skin then gets worse, because the cream contains preservatives the skin is already reacting to.

Plain water on the vulva, nothing inside the vagina, and an unfragranced emollient if the skin is dry. That is the whole of the hygiene advice, and doing less genuinely is the treatment.

Confirm the diagnosis before committing to months of treatment

Before anyone starts a six-month regimen, we want a swab. A self-taken vaginal swab is usually enough, and it does several jobs at once: it confirms whether yeast is actually present, identifies the species (some Candida species respond poorly to the standard azole antifungals, which changes the drug entirely), and picks up BV, trichomonas and other causes. A clinic can also check vaginal pH, which is typically normal in thrush and raised in BV.

Testing for chlamydia and gonorrhoea is reasonable at the same time in anyone sexually active with a change in discharge, because those infections are frequently symptomless and a discharge complaint is a sensible moment to exclude them. You can see the full range of what we assess under conditions we cover.

How longer treatment is usually structured

For both conditions, established practice for recurrence follows an induction-then-maintenance shape: a longer or repeated initial course to clear the episode properly, followed by intermittent suppressive treatment — typically weekly or twice-weekly — for around six months, then a planned stop.

Two honest caveats. First, maintenance suppresses well while it is running; a meaningful proportion of people relapse once it stops, and that is a known limitation rather than a treatment failure on your part. Second, oral antifungals are not used in pregnancy — treatment there is topical, and dosing differs, so pregnancy must be mentioned at the outset.

For BV specifically, the evidence around adjuncts is genuinely mixed. Lactic acid gels and oral probiotics have plausible reasoning and inconsistent trial results. Treating a regular male partner alongside the index patient has recently produced more encouraging results than earlier studies suggested, and practice is actively shifting on it — which is a reasonable thing to raise with your clinician, and not yet a settled recommendation everywhere.

When it is neither thrush nor BV

A substantial share of “recurrent thrush” referred to HeliosCheck.com turns out to be one of these:

• Lichen sclerosus — persistent itch, often worse at night, with pale, thin, crinkled skin and sometimes gradual change in the vulval architecture. It needs a potent topical steroid, not an antifungal, and it needs ongoing follow-up. The NHS overview of lichen sclerosus describes it well.
• Vulval dermatitis — eczema or contact reaction, driven by the products described above.
• Trichomoniasis — a sexually transmitted infection causing frothy, offensive, sometimes yellow-green discharge with itch. Easily mistaken for both conditions, and it needs partner treatment.
• Genitourinary syndrome of the menopause — falling oestrogen thins and dries the tissue, producing soreness, altered discharge and urinary symptoms. Common in the forties onward and frequently misread as infection; our piece on early perimenopause symptoms covers the wider picture.
• Vulvodynia — pain and burning with a normal examination and normal swabs.

When to seek urgent or same-day care

• Fever, lower abdominal pain and abnormal discharge together — this can indicate pelvic inflammatory disease and needs same-day assessment.
• Any bleeding after the menopause, or new bleeding between periods or after sex.
• Severe pain, blisters or ulcers on the vulva, or swelling severe enough to make passing urine difficult.
• Symptoms in pregnancy, particularly with abdominal pain, bleeding or fluid loss.
• A persistent lump, ulcer, or area of skin that does not heal, whatever the itch is doing.
• Feeling systemically unwell — high fever, rigors, confusion, rapid breathing.
• Marked thirst, weight loss or frequent urination alongside recurrent thrush — get glucose checked promptly.

What a consultation would actually cover

A recurrent discharge appointment at HeliosCheck.com spends most of its time on the history, because the history is where the answer usually is. We go through what the discharge looks and smells like, whether itch or smell dominates, what you have taken and what each treatment did, the timing relative to periods, sex and antibiotics, and what you are using on the skin — including anything bought to help.

We will be straightforward about the limits. An online consultation cannot perform a physical or internal examination, and vulval skin conditions in particular are diagnosed by looking. Where examination or a swab is needed, we arrange it and review the results with you; how it works sets out that pathway.

You should come away with a confirmed direction rather than another guess: which condition is being treated and on what evidence, an induction and maintenance plan with a defined end date if one is warranted, a short list of things to stop using, and an agreed point at which we reconsider the diagnosis if the plan is not working. If anything is unclear afterwards, our frequently asked questions may help, or bring it back at review.