Candida in women: vaginal microbiota, balance, and evidence-based strategies

Vulvovaginal candidiasis should not be interpreted simply as the presence of a “fungus to be eliminated”. Candida can indeed be present in the female genital tract even in the absence of disease: the problem arises when the balance between the microorganism, vaginal microbiota, epithelium, and immune response is altered and colonization evolves into a true symptomatic condition. The World Health Organization estimates that vulvovaginal candidiasis affects approximately 70–75% of women at least once in their lives and indicates Candida albicans as being responsible for approximately 85–90% of cases.

This point is fundamental because microbiological positivity for Candida does not necessarily equate to candidiasis. A proportion of healthy women can host Candida at the vaginal level without presenting symptoms and, therefore, the diagnosis must integrate the clinical picture and microbiological examination.

The vaginal microbiota and the role of lactobacilli

In physiological conditions, the vaginal microbiota is often characterized by the predominance of Lactobacillus species. These microorganisms contribute to the stability of the ecosystem through several mechanisms: production of lactic acid, maintenance of an acidic environment, competition with other microorganisms, and interactions with the epithelium and immune system.

However, it is necessary to correct a statement frequently reported in candidiasis information: it is not correct to consider an increase in vaginal pH as the typical mechanism through which candidiasis develops.

Vulvovaginal candidiasis is, in fact, generally associated with a normal vaginal pH, below 4.5. A pH above 4.5 is more characteristic of bacterial vaginosis and trichomoniasis.

This means that the vaginal microbiota and pH are certainly important, but they cannot be used alone to distinguish candidiasis from other forms of vaginitis.

Bacterial vaginosis, candidiasis, trichomoniasis, and non-infectious vaginitis can, in fact, produce overlapping symptoms. Itching, burning, pain, dyspareunia, dysuria, and changes in secretions are not sufficient, on their own, to establish the etiology.

When Candida moves from colonization to infection

Candida albicans is an opportunistic yeast. In favorable conditions, it can adhere to epithelial cells, proliferate, and change its morphology, forming filamentous structures associated with invasive capacity and the inflammatory response.

The transformation from simple colonization to candidiasis is influenced by numerous factors: changes in the vaginal environment, microbiota alterations, antibiotic therapy, pregnancy and hormonal variations, uncontrolled diabetes, and immunosuppression.

It is therefore more correct to speak of a loss of balance in the vaginal ecosystem rather than a simple “infection caused by the presence of Candida”.

The frequent or inappropriate use of antibiotics can also play a role, because the modification of the bacterial component of the ecosystem can favor the proliferation of yeasts. However, this does not mean that every candidiasis is the result of dysbiosis or that the simple administration of probiotics can automatically resolve the infection.

Symptoms are not enough to make a diagnosis

The most characteristic symptoms of candidiasis include vulvar itching, irritation, pain, redness, edema, external dysuria, pain during intercourse, and abnormal vaginal secretions. In more severe cases, fissures and excoriations of the vulva may appear.

The problem is that the same symptoms can appear in other conditions.

For this reason, especially when episodes are frequent, symptoms persist, or the usual treatment does not work, it is important to verify the diagnosis through microscopic examination, culture, or another appropriate test. In complicated or recurrent forms, guidelines recommend particular attention to the identification of the Candida species, because non-albicans species, such as Candida glabrata, may respond differently to antifungal treatments.

Recurrent vulvovaginal candidiasis is generally defined as at least three symptomatic episodes within one year.

Probiotics: can they help the microbiota?

The biological rationale for probiotics is interesting. Some strains of Lactobacillus can contribute to the production of lactic acid, microbial competition, and the stabilization of the vaginal ecosystem.

Clinical research, however, is more complex than simple theory suggests.

A Cochrane review of randomized studies had highlighted a possible benefit of probiotics as an add-on therapy to antifungals, with an increase in short-term clinical and microbiological cure and a possible reduction in recurrence, but with low or very low quality of evidence.

A randomized trial of 55 women with vulvovaginal candidiasis observed, after treatment with fluconazole, a reduction in symptom persistence and the presence of yeast in the group taking Lactobacillus rhamnosus GR-1 and Lactobacillus reuteri RC-14 compared to placebo.

A randomized study conducted in women with recurrent candidiasis also reported a reduction in recurrence with a combination of lactobacilli and lactoferrin used as an add-on treatment after clotrimazole.

The most recent evidence is particularly interesting. A meta-analysis published in 2026, including 14 randomized studies, found that the combination of probiotics and antifungal therapy can improve short-term clinical and mycological cure and reduce some recurrences; however, the authors emphasize that the overall certainty of the evidence remains low or very low and that the long-term results are less consistent.

The scientifically most correct message is therefore this: probiotics can represent a support, especially as a complement to conventional therapy in some women, but they should not be considered a universal substitute for antifungal therapy.

Furthermore, the effect is strictly dependent on the strain, dose, route of administration, and duration. It is not possible to automatically transfer the results obtained with a particular Lactobacillus to any probiotic product.

Tea Tree oil: an interesting antifungal activity, but beware of use

Among the most studied natural substances for antimicrobial activity is Tea Tree oil (Melaleuca alternifolia), whose main bioactive component is terpinen-4-ol.

Microbiological studies have documented the antifungal activity of Tea Tree oil and terpinen-4-ol against several species of Candida. In particular, an experimental model of vaginal candidiasis in rats has highlighted the activity of terpinen-4-ol and Tea Tree oil in accelerating the vaginal clearance of several strains of Candida, including azole-resistant strains.

These results are biologically interesting, but do not equate to the demonstration of clinical efficacy in humans.

It is therefore important not to automatically turn an antifungal activity observed in vitro or in an animal model into a therapeutic recommendation for women.

Tea Tree oil, moreover, is not a harmless substance simply because it is natural. It can cause irritation and allergic reactions, and its composition can change with oxidation and improper storage. A toxicological review recommends avoiding its ingestion and using it topically only in an adequately diluted form.

For this reason, it is not appropriate to independently recommend vaginal irrigations, washes, or intravaginal applications of homemade Tea Tree oil, nor to use arbitrary concentrations. Vaginal washes, moreover, do not represent a recommended prevention strategy and can further alter the vaginal ecosystem. The WHO recommends, among preventive measures, precisely avoiding douching and aggressive or scented personal products.

Calendula, chamomile, sage, aloe, and propolis

Calendula, chamomile, sage, aloe, and propolis are traditionally used in preparations for the vulvar and vaginal area for their soothing, emollient, and anti-inflammatory properties.

Their biological rationale is plausible for the comfort of irritated mucosa and skin, but this does not mean they can be considered equivalent to antifungal therapy.

The distinction is essential: an ingredient may have anti-inflammatory or soothing activity without having demonstrated clinical efficacy in eradicating Candida albicans.

Therefore, in the presence of diagnosed candidiasis, the use of natural preparations may eventually be considered as symptomatic support or for the maintenance of hygiene and comfort, but it should not delay appropriate antifungal treatment.

When candidiasis requires greater attention

Occasional and uncomplicated candidiasis can generally be effectively treated with appropriate antifungal therapy. CDC guidelines indicate that topical treatments based on azoles, in the recommended regimens, achieve a clinical and microbiological response in 80–90% of patients who complete therapy.

It is, however, important to consult a doctor when:

• symptoms are very intense;
• candidiasis recurs frequently;
• symptoms persist after treatment;
• the diagnosis is not certain;
• there is pregnancy;
• diabetes, immunosuppression, or other predisposing conditions are present;
• a non-albicans species is suspected;
• discharge, pain, or bleeding incompatible with the usual presentation appears.

In recurrent forms, simple repetition of self-medication can indeed mask a different diagnosis or a species of Candida less sensitive to conventional treatments. Guidelines recommend a more accurate microbiological evaluation in these cases.

The real goal: protecting the vaginal ecosystem

The most modern perspective on female candidiasis does not simply consist in “fighting Candida,” but in understanding why, in a given woman and at a given time, the balance between microbiota, mucosa, and yeast has changed.

This means considering diet, antibiotic therapy, glycemic control, hormonal factors, immune conditions, possible relapses, and proper intimate hygiene habits.

The vaginal microbiota is a dynamic ecosystem. Lactic acid bacteria can represent an important component of its stability, but their presence is not an absolute guarantee against candidiasis, and their absence does not constitute a diagnosis on its own.

Probiotic research is promising especially as a complementary strategy, but it must be interpreted considering specific strains and formulations. Botanical substances, including Tea Tree oil, must also be evaluated based on the quality of clinical evidence and not solely on the antimicrobial activity observed in the laboratory.

Vaginal health, ultimately, does not depend on the sterilization of the environment: it depends on the maintenance of a balanced biological ecosystem, in which microbiota, mucosa, and immune system can correctly perform their functions.

Bibliographic references

1. World Health Organization. Recommendations for the treatment of Trichomonas vaginalis, Mycoplasma genitalium, Candida albicans, bacterial vaginosis and human papillomavirus (anogenital warts). WHO, 2024.
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