Recurrent Vaginal Infections: Why Do They Keep Coming Back?
Bacterial Vaginosis (BV): Why It Recurs, What Can Cause Similar Symptoms, and Why an Accurate Diagnosis Matters
Almost every week, a patient sits in my practice in Zurich, looking down at her hands, her voice barely above a whisper.
“I’m so worried they’ll notice the smell. Whenever we try to have sex, I tense up. I’m constantly wondering whether it will hurt.”
“Maybe it’s all in my head.”
If you have ever found yourself awake at night wondering, “Why does sex suddenly hurt?” or “Why does my vagina suddenly smell different?”, I want you to know this:
Your symptoms are real. And the impact they can have on your sexuality can be real, too.
An unusual or fishy vaginal odor, thin discharge, irritation or discomfort can affect how you feel in your body and during intimacy. You may worry that your partner will notice the smell. You may start avoiding sex or washing yourself repeatedly because you want to feel cleaner.
Bacterial vaginosis is common and treatable. But it can recur. And when symptoms keep coming back, it is important not to automatically assume that the same condition is responsible every time.
A careful assessment can help distinguish between recurrent bacterial vaginosis, another vaginal condition, a sexually transmitted infection, hormonal changes, or a non-infectious cause.
What is bacterial vaginosis?
Bacterial vaginosis occurs when the vaginal microbiome changes.
The healthy vagina contains many different microorganisms. Lactobacilli play an important role in maintaining a vaginal environment that is generally acidic.
With bacterial vaginosis, protective Lactobacillus species are often reduced, while various anaerobic bacteria increase. These may include Gardnerella species, Prevotella, Atopobium vaginae and other bacteria associated with bacterial vaginosis. These microorganisms can also contribute to the formation of a polymicrobial biofilm on vaginal epithelial cells.
Importantly, bacterial vaginosis is not simply a matter of “catching” one foreign bacterium.
For example, Gardnerella can also be found in women without symptoms. What matters is the composition and interaction of the microbial community and the overall state of the vaginal ecosystem.
Bacterial vaginosis is therefore generally understood as a vaginal dysbiosis rather than a classic sexually transmitted infection. At the same time, sexual activity, having a new sexual partner and not using condoms have been associated with a higher likelihood of bacterial vaginosis. This does not mean that a partner simply “causes” bacterial vaginosis. The relationship between sexual activity, the vaginal microbiome and recurrent bacterial vaginosis is complex.
Why does bacterial vaginosis keep coming back?
Recurrent bacterial vaginosis can be incredibly frustrating, but it does not mean that you have done something wrong.
There is not always one single trigger.
In many cases, several biological factors may interact.
1. The vaginal microbiome can change again
Treatment can resolve the symptoms of an episode of bacterial vaginosis. But the vaginal microbiome does not necessarily remain stable afterwards.
In some women, the microbial community changes again, with a reduction in protective Lactobacillus species and an increase in bacteria associated with bacterial vaginosis.
This may contribute to symptoms returning. Biofilm formation is also thought to play a role in persistence and recurrence.
2. Sex and semen can influence the vaginal environment
Semen has a higher pH than the normally acidic vaginal environment.
Sex can therefore temporarily change the vaginal environment. In some women, these changes may be associated with an increased likelihood of bacterial vaginosis or recurrence. Sexual activity itself is not a simple explanation, however, and the relationship between sex, the vaginal microbiome and recurrence is complex.
This does not mean:
“My partner is causing my bacterial vaginosis.”
It means that sexual activity can be one of several factors influencing the vaginal environment.
3. Your menstrual cycle can also play a role
The vaginal environment changes throughout the menstrual cycle.
Menstrual blood can temporarily increase vaginal pH, and some women notice changes in odor or other vaginal symptoms at particular points in their cycle. Bacterial vaginosis is also reported more frequently around menstruation.
But not every change in vaginal odor during your cycle is a sign of disease.
Vaginal odor can naturally change throughout the menstrual cycle and does not automatically mean that something is wrong.
This is particularly important when it comes to concerns about whether a partner might notice a change in smell.
4. The composition of your Lactobacillus species matters
Lactobacilli are not one single type of bacterium.
There are different species and strains, including Lactobacillus crispatus, Lactobacillus jensenii, Lactobacillus gasseri and Lactobacillus iners. Their properties and their relationship with vaginal health can differ.
A vaginal microbiome dominated by certain Lactobacillus species, particularly Lactobacillus crispatus, has been associated with a more stable, protective vaginal environment.
This distinction is also important when talking about probiotics.
There are products containing Lactobacillus that are taken orally, as well as products intended for vaginal use. There are also commercially available vaginal microbiome products, sometimes marketed as vaginal or “yoni” kits, which may contain different bacterial species or strains.
But Lactobacillus is not simply Lactobacillus.
Different products can contain different species, strains, doses and formulations.
Some studies of oral and vaginal probiotics have produced promising results, but the evidence remains inconsistent. A recent systematic review and meta-analysis of vaginal Lactobacillus tablets did not find a clearly established reduction in recurrent bacterial vaginosis. At the same time, other studies have reported potential benefits with specific strains and formulations.
For this reason, probiotics should not currently be considered a replacement for appropriate treatment of diagnosed bacterial vaginosis. Whether a probiotic product might be useful in an individual case depends on the specific product, strain and clinical situation.
The key message is:
The strain matters and more is not necessarily better.
5. Hormonal changes can affect the vaginal environment
Hormonal changes can also influence the vaginal tissue and microbiome.
This becomes particularly relevant during perimenopause and after menopause.
As estrogen levels decline, the vaginal tissue can become thinner, drier and less elastic. This can cause burning, itching, irritation, dryness, pain during sex and sometimes changes in vaginal discharge or the vaginal environment.
This group of symptoms is known as genitourinary syndrome of menopause.
This is why, particularly after menopause, recurrent itching, burning, discomfort or discharge should not automatically be assumed to be a yeast infection or bacterial vaginosis.
Why an accurate diagnosis matters
Odor, discharge, itching and burning can provide clues — but symptoms alone do not always tell us what is causing them.
Depending on the situation, a gynecological examination, assessment of vaginal pH, microscopy or targeted laboratory testing may be useful. The goal is not to perform every possible test for every symptom. It is to choose the appropriate assessment for the individual situation.
This becomes particularly important when symptoms return shortly after treatment or when the same diagnosis and treatment are repeatedly used without reassessing the underlying cause.
Sometimes it really is recurrent bacterial vaginosis.
Sometimes it is Candida.
Sometimes it is a sexually transmitted infection.
Sometimes it is a hormonal or dermatological condition.
And sometimes there is more than one factor involved.
What can I do if bacterial vaginosis keeps coming back?
If your symptoms return, do not automatically assume that you have another episode of bacterial vaginosis.
If it is genuinely recurrent bacterial vaginosis, further treatment may be appropriate. But the first step is making sure that the current symptoms actually fit the diagnosis.
A repeat assessment can help determine whether this is recurrent bacterial vaginosis, another vaginal condition, a sexually transmitted infection or a non-infectious cause. It can also help determine whether a different treatment or a longer-term management strategy is appropriate.
You can also try to minimize unnecessary irritation of the vulvovaginal area:
Avoid vaginal douching.
Avoid heavily fragranced intimate products.
Avoid aggressive or excessive washing of the vulva.
Pay attention to whether symptoms seem to occur in relation to your menstrual cycle or sexual activity.
For women with multiple recurrences, there are medical treatment strategies that go beyond treating a single episode. The appropriate approach depends on how frequently symptoms occur, previous treatments and the individual clinical situation.
When should you see a gynecologist?
A gynecological assessment is particularly important if:
Your symptoms keep coming back.
An unusual odor or discharge persists.
Itching or burning continues despite treatment.
Symptoms return shortly after treatment.
Sex has newly become painful.
You have lower abdominal or pelvic pain.
You experience bleeding after sex.
You experience any vaginal bleeding after menopause.
You notice new or persistent changes to the skin or mucous membranes of the genital area.
You are concerned about a possible sexually transmitted infection.
Bleeding after menopause or recurrent unexplained bleeding should not simply be treated as a vaginal infection.
When recurrent bacterial vaginosis or pain affects your sex life
At Oh Yes Baby Yes, Johanna Janku, MD, FMH, specialist in gynecology and obstetrics and specialist in sexual medicine, offers confidential, evidence-based consultations for intimate health concerns.
Together, you can explore your symptoms, possible causes, appropriate investigations and treatment options.
Consultations are available in our practice in Zurich and online.
confidential · evidence-based
Sources & further reading
Centers for Disease Control and Prevention. Bacterial Vaginosis – STI Treatment Guidelines.
American College of Obstetricians and Gynecologists. Vulvovaginal Health.
American College of Obstetricians and Gynecologists. Disorders of the Vulva: Common Causes of Vulvar Pain, Burning, and Itching.
American College of Obstetricians and Gynecologists. Vaginitis.
American College of Obstetricians and Gynecologists. Diagnosis and Management of Vulvar Skin Disorders.
American College of Obstetricians and Gynecologists. Persistent Vulvar Pain.
American College of Obstetricians and Gynecologists. When Sex Is Painful.
