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What is Thrush?

Updated: Feb 14

Thrush is a Yeast Infection - What's That?

Also known as Yeast Infection or Vulvovaginal Candidiasis, Thrush is caused by an overgrowth of yeast microorganisms in the vagina. It’s commonly associated with (or triggered by) a yeast overgrowth in the intestines, but the symptoms from the vagina may be much more obvious than any from the gut.

The most common yeast culprit is Candida Albicans, but there are other species of Candida that can cause the same issues. Candida yeasts are typically present in a healthy vagina, and we still don’t know exactly why or what triggers a harmless population of Candida to overgrow and become pathogenic (a problem).

A yeast is a type of fungus.
Thrush is typically caused by Candida species of yeast.
Bakers and brewers yeasts are species of Saccharomyces, not Candida.
Thrush infections can also occur in the mouth and throat.
Thrush in a baby’s mouth can transfer to the nipple of the breastfeeding mother.

There has been much research into the types of bacteria in the vaginal microbiome, but comparatively little into their fungal cousins, including yeasts. This is gradually changing because of the need to find effective treatments for fungal infections.

You may already know (more than you want to) what happens when Candida takes over the microbiome, because 75% of women suffer Thrush at some point. An unlucky few suffer recurrent infections – the medical definition of recurrent Thrush is four or more times a year.

Candida overgrowth can go unnoticed, but most women will notice some or all of these symptoms affecting not just the vagina but also the external skin and labia:

  • Severe itching

  • Vaginal discharge: white and cottage cheese-like, but no strong odour

  • Vulval burning

  • Vulval soreness and irritation

  • Pain when urinating or during sex.

These symptoms could also describe Bacterial Vaginosis, trichomoniasis or gonorrhoea so be wary of self-diagnosing, especially if the condition is recurring.

If an unpleasant odour is a symptom, there is probably something other than Thrush involved.

Why is Thrush so itchy...

How does a tiny yeast cell cause so much itching? Candida can be a happy little round cell… or it can grow a tail (called a hyphae) which digs into any tissue is comes into contact with, causing damage and inflammation.  

Candida with a tail is Candida that itches.

The lactic acid produced by the friendly Lactobacilli bacteria in a healthy vaginal microbiome inhibits the growth of this itch-causing hyphae.

...and so hard to get rid of?

Candida also has the sneaky ability to produce its own glue – a protein on its surface that helps it stick to things like catheters and pessaries. This makes it harder to treat effectively.

High levels of sugar in the diet increase the production of this protein, giving Candida an advantage and making recurrence of Thrush more likely.

Risk Factors for Thrush Explained

  • Genetic Predisposition

  • Diabetes and Autoimmune diseases

  • Increased estrogen levels eg pregnancy, oral contraceptive use, hormonal therapies

  • Antibiotics

  • Intrauterine devices

  • Frequent sexual intercourse

  • Use of condoms and spermicides

Why yes: using condoms protects you against Bacterial Vaginosis and STIs, but makes you more likely to get Thrush.

Increased estrogen levels result in increased glycogen available to feed microorganisms – usually a good thing while Lactobacilli are dominant. But if yeast can get a foothold, it will compete for the glycogen and love the high estrogen and resulting glycogen.

Antibiotics disrupt the protective bacteria, allowing yeast microbes to multiply. Not all antibiotics have this effect, which has historically made it difficult to prove the relationship between antibiotics and Thrush.

An article on Antibiotics later in this series will explain that not all antibiotics disrupt the vaginal microbiome.

Intrauterine devices are usually contraceptive or hormonal treatment devices. They provide a surface for biofilm to form on. Biofilm is a thin layer of cells that adhere to a surface, and a bacteria or fungus hiding under biofilm is very difficult to target with medication.

Objects that are inserted in the vagina - pessaries, menstrual cups and sex toys - can also host biofilms.

Kill the Feral Fungus

Thrush can be formally diagnosed and the exact yeast species identified by medical tests. It should be properly identified before using antifungal treatments (either prescription or over-the-counter), because antifungals have the same problem antibiotics do.

Overuse or misuse of antifungals will allow the organism to develop resistance to the medication. This makes Thrush worse for everyone, as resistant strains spread.

Non-prescription strategies for Thrush are particularly appropriate if the condition is occurring only occasionally.

Extracts of the plant Calendula Officinalis have been found effective in treating Thrush. Lots of commercial products are available, but be wary that many are not suitable to apply to sensitive genital tissues. (I will add a post with more detail about Calendula, so stay tuned.)

Simple cases of yeast overgrowth have been found to respond to dietary changes. These strategies might be useful as an addition to medical management. You should notice a difference within a day if this is true for your case. Try to stick with the changes for a week or two even if symptoms are resolved, to reduce recurrence.

General recommendations for managing yeast growth:

  • Reduce sugar consumption

  • Reduce refined carbs eg white bread

  • Eat fermented foods

  • Supplement with a probiotic containing Saccharomyces boulardii

Research suggests that reducing sugar and refined carbs starves the yeast and reduces its ability to produce the protein used to adhere to surfaces.

Fermented foods and probiotics supply an army of micro-organisms that are friendly to you, but unfriendly to Candida yeasts. The yeast is usually overgrowing in the intestines as well as in the vagina, so what you eat can make a difference.

Saccharomyces boulardii is properly named Saccharomyces cerevisiae var. boulardii – it’s another strain of the species used in brewing and baking, but it acts differently to the 'kitchen' yeasts. It has been found to be useful in overwhelming Candida yeasts.

Saccharomyces boulardii is contained in a variety of commercial probiotic supplements, and more hit the market regularly. It may be listed on packaging as S. Boulardii or even SB.

Where Yeast Hides, Inside

Thrush that has frequently recurred despite antifungal treatments may have established a layer known as biofilm within your intestines or vagina. This is difficult to remove and it allows the yeast to regrow after treatments that should have controlled it.

There are very few products available that attack this biofilm, but at the time of writing, one that has been tested specifically on Candida biofilms is called Interfase Plus. It uses an enzyme in capsule form to target biofilm in the gut rather than in the vagina. Yeast overgrowth frequently starts out in the intestines (even if the noticeable symptoms are vaginal) so this may be effective for some stubbornly recurrent cases of Thrush.

The product Interfase Plus is made by Klaire Labs. Forecast Wellness has no association with the company and is mentioning the product based solely on the published results of a couple of research studies. You should do additional research as available products change rapidly and new or better information may be available by the time you read this!

Dr Google Says:

There are a number of other historical or uncommon treatments recommended for Thrush, but these typically have very little scientific backing and so cannot be recommended here as methods for managing the vaginal microbiome.

It could certainly be argued that lack of scientific research only means the research hasn’t been done, it doesn’t mean the treatment doesn’t work.

One of the reasons the research isn’t done is that many of the suggestions involve douching – washing out the inside of the vagina. Because douching is known to be a strong risk factor in causing bacterial vaginosis, it is difficult to get research approval to use douching in a scientific study.

Some of the unproven possibilities you may come across include:

Gentian Violet – medically prescribed before antibiotics and antifungals become available, it was painted on the walls of the vagina by a doctor. It can be acquired for home use but issues include ulceration if too much is used. Carefully check the instructions for how much you need to dilute it if you choose to try this outdated remedy. It will also stain everything purple – including you, your underwear, and any sexual partner.

Potassium Sorbate – this is a food additive (E2O2) that stops yeasts reproducing. It might be considered safe to use because it is approved for use in organic cosmetics, and is present in some feminine hygiene wipes. The naturopathic recommendation is typically to mix a teaspoon (3g) of potassium sorbate granules in 400ml of water, soak a tampon in the solution and insert. I haven't found any studies assessing this for effects or side-effects.

Milk Kefir or yoghurt – these are often suggested for their probiotic contents, but if they are recommended as a douche they are best avoided. There are safer and healthier ways to deliver probiotics to the vagina, and the bacteria in these products aren't the ideal vaginal species anyway. If choosing to try these treatments, be very careful to choose natural products that contain no added sugars, flavours or fruit.

Providone-Iodine – an absolute NO for anyone with thyroid issues, unless medically advised. For others it can still pose a risk to thyroid function especially if used frequently. It is available commercially as a betadine douche, and studies suggest that Lactobacilli do recover from the treatment. Again, douching should be considered with caution and is probably better avoided. This one will stain you brown. It is likely to deliver symptom relief but has not been found to actually cure the condition. For many, this means the risk is too great for the reward to be worth it.

Final Note

A strong and balanced vaginal microbiome is more likely to prevent the development of Thrush. Keep an eye on this blog for more articles about keeping the vaginal microbiome healthy.

Bird image by Ray Hennessy on Unsplash

Check out the rest of the series on Vaginal Health HERE!

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