Vaginal Candidiasis (Thrush): Causes, Symptoms & Recurrence
Vaginal thrush is one of the most common reasons people seek care for genital symptoms, and also one of the most commonly self-diagnosed incorrectly. Clinically known as vulvovaginal candidiasis, it happens when Candida yeast — usually Candida albicans — overgrows and disrupts the vagina’s normal microbial balance.
This page explains what vaginal candidiasis is, its common symptoms and causes, how it differs from other vaginal conditions, why some infections recur, and when medical assessment is appropriate.
What Is a Yeast Infection?
Vaginal thrush (vulvovaginal candidiasis) happens when Candida yeast — usually Candida albicans — overgrows in the vagina and surrounding tissue. Small numbers of Candida organisms are a normal part of vaginal flora for most women; symptoms appear when something disrupts that balance and lets the yeast multiply.
Thrush is not a sexually transmitted infection, though sexual activity can sometimes trigger symptoms in people who are already prone to it. Most presentations are uncomplicated and respond well to standard antifungal treatment, but a proportion turn out to be something else — which is why the symptom pattern and history both matter before treatment is decided.
Common Symptoms of Vaginal Thrush
Symptoms vary in severity and don’t all need to be present at once. The pattern most consistent with uncomplicated thrush includes:
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Vulval and vaginal itching, often persistent rather than coming and going
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Thick, white discharge without a strong odour (sometimes described as “cottage cheese-like”)
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Redness, swelling or soreness of the vulva
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Stinging or burning with urination or intercourse
The absence of a strong odour is one of the more useful distinguishing features — a fishy or otherwise noticeably different smell points more toward bacterial vaginosis than thrush, and changes what treatment is appropriate.
What Causes Thrush?
Thrush usually develops when something shifts the vagina’s normal microbial balance, rather than from a single identifiable trigger. Recognised contributing factors include:
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Recent antibiotic use, which can reduce protective lactobacilli
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Hormonal changes — pregnancy, the combined pill, or the menstrual cycle
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Poorly controlled diabetes
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Conditions or medications that suppress immune function
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Prolonged moisture or tight, non-breathable clothing
Identifying which of these applies matters for preventing the next episode, not just treating the current one.
Why an Accurate Diagnosis Matters
A significant number of people who self-treat for “thrush” are actually dealing with something else. Conditions that commonly get mistaken for candidiasis include:
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Bacterial vaginosis
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Contact or irritant dermatitis
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Sexually transmissible infections
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Vulvodynia and other inflammatory vulval conditions
Repeated self-treatment when the underlying cause is actually something else is one of the more common reasons symptoms become recurrent or never fully settle. Where the pattern is unclear, or treatment hasn’t worked as expected, further assessment — potentially including a vulvovaginal swab for microscopy and culture — is the appropriate next step, rather than trying another course of the same treatment.
Treatment Principles
For uncomplicated thrush, first-line options are well established:
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A single dose of oral antifungal medication (e.g. fluconazole), where appropriate
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Topical antifungal creams or vaginal pessaries
Recurrent candidiasis — generally four or more confirmed episodes within a year — is managed differently to a single episode, usually with a longer induction and maintenance course, and it should prompt a look at contributing factors rather than repeating the same short course. Antifungal treatment without a clear diagnosis, or repeated self-treatment that isn’t working, can mask another condition and delay appropriate care.
When Medical Assessment Is Appropriate
Medical assessment is appropriate when symptoms are new, uncertain, recurrent, atypical or have not improved with appropriate treatment. Because several vaginal conditions can cause similar symptoms, persistent or unusual presentations may require examination or testing rather than repeated empirical antifungal treatment. For patients seeking online assessment of a typical presentation, see DocTel’s Thrush Treatment Online service page.
Where symptoms include red-flag features, or the diagnosis remains uncertain, an in-person examination and appropriate testing may be required.
Recurrent Candidiasis
Recurrent vulvovaginal candidiasis refers to repeated episodes of symptomatic thrush over time; the exact number used to define recurrence varies between clinical guidelines. It affects a meaningful minority of women and often needs a different approach to a single episode — a longer treatment course, attention to contributing factors such as diabetes control or antibiotic exposure, and sometimes confirmatory testing rather than assuming every episode is the same.
If you’re treating what you believe is thrush more than a couple of times a year, that pattern is worth raising with a practitioner rather than continuing to self-treat — recurrence can also be the first sign that the original diagnosis was wrong.
Pregnancy, Diabetes and Immune Suppression
Some groups need extra care in how thrush is assessed and managed:
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Pregnancy — thrush is common in pregnancy, and treatment options are more limited; oral antifungal medication is generally avoided and topical treatment is preferred. This should be managed with a practitioner aware of the pregnancy.
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Diabetes — poorly controlled blood glucose is a recognised driver of recurrent thrush, and ongoing episodes may prompt a review of glucose control as much as the infection itself.
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Immune suppression — people who are immunocompromised, including through certain medications or underlying conditions, can develop more persistent or atypical presentations and may need a lower threshold for in-person review.
When to Seek In-Person Assessment
Most uncomplicated thrush can be safely identified from a typical symptom pattern. See a practitioner in person, rather than relying on telehealth alone, if you notice:
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Sores, ulcers, blisters or unusual lesions on the vulva
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Unexplained vaginal bleeding, especially after intercourse or after menopause
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Fever, pelvic pain, or feeling generally unwell alongside vaginal symptoms
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Symptoms that haven’t improved after appropriate treatment, or that keep recurring
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Uncertainty about whether symptoms are due to thrush, an STI, or another cause
These features don’t necessarily mean something serious is happening, but they do mean a description of symptoms alone isn’t enough to safely guide treatment — an examination, and sometimes testing, is needed first.
Assessment and Diagnosis
Assessment of suspected thrush starts with the symptom pattern, duration, previous episodes and treatment history, together with relevant factors such as pregnancy, diabetes or recent antibiotic use. When the presentation is not typical, examination or testing may be needed to distinguish candidiasis from bacterial vaginosis, sexually transmissible infections, dermatitis and other vulval conditions.
The aim is to confirm that the symptoms are consistent with candidiasis before treatment is repeated, particularly when symptoms persist or recur.
Is thrush an STI?
No. Candida overgrowth isn’t classified as a sexually transmitted infection, although sexual activity can trigger symptoms in some people already prone to thrush.
Can I just use an over-the-counter antifungal instead of seeing someone?
For a first, typical episode, that’s a reasonable option for many people. It becomes less appropriate if symptoms don’t improve, keep recurring, or don’t match the usual pattern — at that point, further self-treatment risks masking something else.
Need Assessment or Treatment for Thrush?
If you have symptoms consistent with uncomplicated thrush and want clinical assessment or treatment, visit our dedicated Thrush Treatment Online page. Atypical, recurrent or red-flag symptoms may require in-person assessment.