Introduction

Photo of a pregnant woman (PantherMedia / Iñigo Quintanilla) Vaginal yeast infections (thrush) can cause itching, burning or abnormal vaginal discharge. In many women the external (outer) sex organs such as the labia are inflamed too. Sometimes vaginal yeast infections don't cause any symptoms at all.

Vaginal yeast infections occur when too much yeast grows in the vagina, leading to an inflammation. Yeast is a type of fungus. Along with bacterial infections (bacterial vaginosis), yeast infections are among the most common causes of inflammation in the vagina and on the outer part of the female genitals.

Women are particularly likely to have vaginal yeast infections during certain phases of life, such as pregnancy. Other things that increase their risk include a weakened immune system and taking certain medications.

Yeast infections often clear up after a short course of treatment with vaginal suppositories or creams. Sometimes it can be a good idea to take tablets.

Symptoms

The typical symptoms of a vaginal yeast infection are itching, an unpleasant burning feeling and pain. The membranes lining the vagina become red and have a whitish coating. The symptoms may get worse a few days before your period starts. If the inflammation has spread to the external genitals, areas such as the labia might be red and swollen too.

Vaginal yeast infections often lead to a whitish-yellowish vaginal discharge. It can be watery or chunky, a bit like curdled milk or cottage cheese. Sex can be painful when you have a yeast infection. If the urethra (the tube that you pee out of) is inflamed too, peeing also hurts.

Causes and risk factors

Vaginal yeast infections are usually caused by a type of yeast called Candida albicans. It’s normal for this yeast to live in the mucous membranes lining the genitals. There are usually only small amounts of it, though, so it doesn't cause any problems.

But the healthy balance of microorganisms (germs) living in the membranes is sometimes disrupted – for instance, through pregnancy or medication.

The level of estrogen in the body is particularly high during pregnancy. That can upset the healthy balance and increase the likelihood of developing a vaginal yeast infection. Taking the contraceptive pill (birth control pill) affects a woman's hormone levels in a similar way to pregnancy. So women who take the pill are also more likely to have yeast infections.

Some illnesses increase the risk of vaginal yeast infections. These include diabetes and other diseases that weaken the immune system. Various medications can increase the risk too, such as antibiotics, steroids, hormone therapy, radiotherapy and chemotherapy. Other factors that increase the risk of vaginal yeast infections include stress, washing your genitals with soap, wearing synthetic and tight clothes, sweating and using “non-breathable” panty liners or sanitary pads. These things allow the yeast to thrive, leading to an inflammation.

Sometimes women catch the infection from someone else, if a lot of the yeast get into the vagina from the outside – for instance, through sex with a man who has a yeast infection on the glans (head) of his penis.

Prevalence and outlook

Yeast infections are the second most common cause of vaginal inflammations (bacterial infections are the most common cause). Up to 75 out of 100 women have a vaginal yeast infection at least once in their life. These infections are most common in women of childbearing age. If women get yeast infections after menopause, it may be due to taking medication such as estrogen hormones.

The symptoms are often very mild, and sometimes there are no symptoms at all. They are only rarely severe. Then more intensive treatment is needed. This is also necessary if a woman has yeast infections several times a year or if the infections are caused by a weakened immune system.

Effects

If the membranes lining the vagina are inflamed or if itchy skin in the outer genital area is scratched open, that also makes it easier for other germs to thrive there, making the symptoms worse. The inflammation can also easily spread to nearby tissue, such as the opening of the urethra.

Serious complications are very rare and are usually associated with a weakened immune system, for instance due to cancer treatment or AIDS. Then the inflammation can get worse and spread further.

In pregnant women, vaginal infections can somewhat increase the risk of complications such as premature labor, miscarriage, or premature birth in pregnant women. Vaginal yeast infections can also be passed on to babies during the birth. This could lead to diaper rash (nappy rash) or to an inflammation in the membranes lining the newborn baby's mouth, for instance.

People who have a medical problem in their genital area are often embarrassed to talk about it. As a result, women may put off treating a yeast infection or they may not tell their partner about it. This can make the infection last longer than necessary and increase the risk of infecting others.

Diagnosis

Vaginal yeast infections can usually be diagnosed based on a description of the symptoms and by looking at the lining of the vagina. If the doctor isn't sure, they may take a sample of vaginal discharge fluid and examine it to look for yeast.

Women who keep getting yeast infections or have severe symptoms may need to have further tests in order to find out whether they have certain risk factors such as a weakened immune system. If you have recurrent yeast infections it may be a good idea for your partner to go to the doctor and be checked too.

Prevention

People who have a weakened immune system are sometimes advised to take medicine to prevent fungal infections (known as antifungal drugs or antimycotics). Some women also use antifungal medication while taking antibiotics, as a precaution. But there’s not enough good research to be able to say whether this helps to prevent vaginal yeast infections. Women who are otherwise healthy don't need to take any special preventive measures. If your partner has a yeast infection, it's best to wait until the infection has cleared up before having sex with them again, otherwise you might catch it from them.

Some women use special products containing probiotics. Depending on the type of product, they are either swallowed or inserted into the vagina. The aim is to restore or promote a healthy balance of germs (healthy vaginal flora). But there’s not enough good research in this area to be able to say whether probiotics can prevent yeast infections.

Some things do more harm than good: For instance, women should avoid using vaginal douches or female intimate hygiene products. These products upset the natural balance of germs, increasing the risk of infections.

Treatment

One course of treatment is usually enough – in the form of a suppository or cream placed inside the vagina using an applicator, so it comes into contact with the inflamed tissue lining the vagina. The recommended duration of treatment varies, depending on the product used. But it usually takes only 1 to 6 days. The treatment can cause burning or itching.

Some medications can also be taken orally (swallowed) in the form of a single tablet. But that can lead to interactions with other medications and result in side effects such as nausea, diarrhea or a headache. Oral antifungal medication also isn’t suitable for pregnant women.

If you have frequently recurring yeast infections or an increased risk of complications – for instance, due to a weakened immune system – it can be a good idea to seek medical advice from a doctor. You may then need a more intensive treatment, such as antifungal tablets for several months. It usually isn’t necessary for your partner to be treated. This is only done if they have a genital yeast infection too.

It’s also possible to use suppositories or capsules containing live lactic acid bacteria (probiotics). These treatments are designed to protect and restore the natural balance of germs in the vagina (the vaginal flora). There’s not yet enough evidence to say whether they work.

Some women also insert garlic cloves or tampons – for instance, soaked in tea tree oil – into their vagina. Others use natural yogurt to improve the pH inside their vagina (make it more acidic). But there’s a lack of research on how effective or safe these kinds of home remedies are. The possible risks include allergic reactions or irritated mucous membranes.

It’s never a good idea to use a vaginal douche because that could make the inflammation worse.

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