Sweat, sand, and swimwear: How to support your vaginal microbiome this summer

Summer brings a welcome shift in pace. Warmer days, holidays, spontaneous plans, and more time spent outdoors. But while we're enjoying the sunshine, many women notice something else too: irritation, discomfort or recurrent vaginal infections that seem to appear out of nowhere.

You might notice it after a long day at the beach, sitting in damp swimwear, or staying in activewear longer than planned (it happens to the best of us!). It might start  as mild irritation, a change in discharge, or a subtle shift in odour. Sometimes it’s even itching that won’t go away. These symptoms can feel frustrating, uncomfortable, and at times, difficult to talk about. And yet they’re incredibly common, affecting about 1 in 4 women of reproductive age (1). So if things feel a little “off” down there during the warmer months, you’re not alone.

In this article, we talk about why vaginal infections occur more frequently in warmer months, the fascinating science of the vaginal microbiome, and practical tips to support your intimate health this summer (and in fact, all year round).

A quick reminder before we start, the vagina is the internal muscular tube connecting the external genitals to the uterus (womb) and the vulva is the term given to the external genitals - the clitoria, labia majora (fatty, outer, hair bearing lips) and labia minora (thinner inner lips).

Why are vaginal infections more common in summer?

Summer can be surprisingly disruptive for the vaginal microbiome. Many of the things we associate with warmer weather can bring disruption to our vaginal pH and the balance of bacteria that reside there.

Four common disruptions, which we like to think of  as the “4 S’s”, include:

• Sweat: Remaining in sweaty clothes for extended periods of time (i.e. wearing yoga pants long after your class ended), leads to the perfect environment for fungi and other yeasts which like hot, damp conditions and can lead to fungal skin infections, and friction can also lead to irritation

• Swimming: Chlorine and saltwater from pools, hot tubs, and the ocean, can dry out the vulval skin as well as disrupt vaginal bacterial balance, causing irritation, a burning sensation as well as increasing the risk of thrush and bacterial vaginosis

• Sand: Can cause friction and general discomfort down there.

• Synthetics and tight swimwear: Wearing synthetic, non-breathable, tight swimwear, or staying in wet swimwear for too long, traps heat and moisture, creating the ideal environment for unwanted bacteria and fungi.

What are common conditions affecting the vaginal microbiome?

The two commonest vaginal conditions affecting women are bacterial vaginosis (BV) and vulvovaginal candidiasis (Thrush).

Bacterial vaginosis (BV)

BV is described as a dysbiosis (imbalance) of the vaginal microbiome. The vagina is naturally acidic, with a pH of around 3.8-4.5, while the vulva has a pH of about 5.  Healthy lactobacilli bacteria in the vagina keep the pH low, so if there is a reduction in the amount of Lactobacilli the pH of the vagina can rise.  This change means that other opportunistic bacteria such as Gardnerella vaginalis, Prevotella species, Mycoplasma hominis, and Mobiluncus species have a chance to overgrow.

BV is extremely common, affecting around a quarter of women of childbearing age and can impact many areas of life. While some women with BV may not notice any symptoms, others may experience (2):

• Unusual discharge from the vagina

• A strong fishy or musty odour 

• Itching or irritation 

• Burning during urination 

Recurrence is high, affecting nearly 60% of women within 12 months and 1 in 4 one month after treatment (1).

Vulvovaginal candidiasis (Thrush)

Thrush is a fungal infection in the vagina leading to inflammation of the vagina and/or vulva, usually from   a type of yeasts belonging to the genus Candida. These yeasts are naturally present in the vaginal microbiome, but when they overgrow, symptoms can develop. Typical symptoms include (3):

• Itching or irritation around the vagina

• Burning during urination 

• Pain

• A cottage cheese-like, creamy/white discharge which doesn’t tend to have an offensive smell.

Thrush is the second most common vaginal infection in women of reproductive age, with around 75% of women experiencing at least one episode in their lifetime (3). Candida albicans is responsible for 80-90% of cases, and recurrence is common, with over 60% of women experiencing multiple episodes per year (3).  

What’s the role of the vaginal microbiome in preventing BV and Thrush?

The idea that our bodies are host to trillions of beneficial microbes is still a relatively new concept for many of us. And, while the majority of research efforts to date have focused on the gut microbiome, we know now that the vagina has its own microbiome too, and it's one of the most important ecosystems in the female body.

A healthy and balanced vaginal microbiome is typically dominated by Lactobacillus species, which play a key role in maintaining balance and protecting against infection (4). Far from being passive freeloaders, these beneficial bacteria actively work to keep the vaginal environment stable, and help prevent both BV and Thrush. Specifically, a Lactobacillus-dominant microbiome helps to (5):

• Maintain a slightly acidic vaginal pH (3.8–4.5)

• Prevent pathogens from adhering to the vaginal lining

• Compete with harmful microbes for nutrients

• Produce antimicrobial substances such as lactic acid, hydrogen peroxide, and bacteriocins, which inhibit the growth of harmful bacteria and yeast

Live bacteria, specifically Lactobacillus acidophilus, La-14® and Lactobacillus rhamnosus, HN001™, have shown impressive results in supporting vaginal health and managing BV and Thrush in randomised placebo-controlled trials (6-9).

How can I protect my intimate health this summer?

To prevent BV and Thrush this summer (and the rest of the year too!) a few simple habits can go a long way:

• Choose cotton underwear, if you can’t/don’t want to then aim for the gusset of the underneath to be made of cotton

• Don’t wear underwear to bed

• Change out of wet swimwear as soon as possible

• Rinse off with fresh water after the beach or pool

• Don’t spend all day in sweaty or tight activewear

• Drink plenty of water in warmer days (yes, hydration is important for vaginal health too)

How can I manage BV if I already have it?

Several clinical studies have demonstrated the effectiveness of the live bacteria strains La-14® and HN001™, in combination with lactoferrin, in managing BV (6-8). This combination helps to:

• Colonise the vagina after oral consumption in as little as 7 days 

• Improve BV symptoms, including vaginal discharge and itching

• Normalise the Nugent score, indicating a healthier bacterial balance

• Reduce BV recurrence rate by approximately 50% at 6 months compared to placebo. This is particularly important given the high recurrence rates seen in BV.

Bacterial vaginosis is treated using antibiotics, which can be oral, or in the form of vaginal creams or gels available on prescription from  your GP.

How can I manage Thrush if I already have it?

Supplementation with La-14®, HN001™ and lactoferrin, has also demonstrated efficacy in managing Thrush. In a double-blind, placebo-controlled trial (9) involving women treated with topical clotrimazole, supplementation during treatment followed by a maintenance phase (total of 6 months) resulted in:

• Significant improvements in symptoms such as itching and discharge, compared to placebo, at 3 and 6 months

• Significantly reduced recurrence rates at both 3 and 6 months follow-up compared to placebo

Thrush treatments are antifungal medications which can be oral, or vaginal pessaries or internal vaginal creams as well as an antifungal cream for external itching.  The external cream alone is unlikely to be sufficient to treat thrush.  Many of these are available without a prescription. 

If you try over the counter treatments and they aren’t effective please see your doctor, sometimes thrush can be persistent and require longer courses of treatment.  However, not all vaginal and vulval itching is thrush so if they don’t work please seek medical advice.  If you have recurrent thrush, where you get repeated episodes then please also see your doctor.

When it comes to live bacterial supplements, you need to be specific, choosing the right strain, at the right time, at the right dose. Want to know which bacterial supplement is right for you? You can find the latest evidence and guidance here.

References

1. Bacterial vaginosis | Health topics A to Z | CKS | NICE

2. Bacterial vaginosis, WHO, 2025

3. Candida - female genital | Health topics A to Z | CKS | NICE

4. Chen X, Lu Y, Chen T, Li R. The Female Vaginal Microbiome in Health and Bacterial Vaginosis. Front Cell Infect Microbiol. 2021 Apr 7;11:631972. doi: 10.3389/fcimb.2021.631972. PMID: 33898328; PMCID: PMC8058480.

5. Amabebe E, Anumba DOC. The Vaginal Microenvironment: The Physiologic Role of Lactobacilli. Front Med (Lausanne). 2018 Jun 13;5:181. doi: 10.3389/fmed.2018.00181. PMID: 29951482; PMCID: PMC6008313.

6. De Alberti D, Russo R, Terruzzi F, Nobile V, Ouwehand AC. Lactobacilli vaginal colonisation after oral consumption of Respecta(®) complex: a randomised controlled pilot study. Arch Gynecol Obstet. 2015 Oct;292(4):861-7. doi: 10.1007/s00404-015-3711-4. Epub 2015 Apr 9. PMID: 25855055.

7. Russo R, Edu A, De Seta F. Study on the effects of an oral lactobacilli and lactoferrin complex in women with intermediate vaginal microbiota. Arch Gynecol Obstet. 2018 Jul;298(1):139-145. doi: 10.1007/s00404-018-4771-z. Epub 2018 Apr 10. PMID: 29637269.

8. Russo R, Karadja E, De Seta F. Evidence-based mixture containing Lactobacillus strains and lactoferrin to prevent recurrent bacterial vaginosis: a double blind, placebo controlled, randomised clinical trial. Benef Microbes. 2019 Feb 8;10(1):19-26. doi: 10.3920/BM2018.0075. Epub 2018 Dec 10. PMID: 30525953.

9. Russo R, Superti F, Karadja E, De Seta F. Randomised clinical trial in women with Recurrent Vulvovaginal Candidiasis: Efficacy of probiotics and lactoferrin as maintenance treatment. Mycoses. 2019 Apr;62(4):328-335. doi: 10.1111/myc.12883. Epub 2019 Feb 20. PMID: 30565745.