Vaginal yeast infections are caused by Candida yeasts. But, it’s important to note that having Candida in your vaginal microbiome doesn’t necessarily mean you have an infection. Turns out these yeasts can be harmless members of a healthy vaginal microbiome.
So why do they make a mess down there sometimes? Well, scientists are not totally sure how this happens. It’s probably a combination of several factors, such as your vaginal microbiome composition, other diseases, and hormonal changes [1].
What we do know is that certain things can increase your risk of getting a yeast infection if you have Candida as part of your vaginal microbiome:
- Antibiotics
- Stress
- Douching, scented soaps, tight underwear
- A weakened immune system
- Pregnancy
- Hormonal birth control pills high in estrogen
- Estrogen therapy
- Obesity
- Untreated diabetes or gestational diabetes
- Genetic factors [1], [2]
So when the conditions are right, Candida may take the opportunity to overgrow, build up an army, and have fun teasing immune cells. This leads to a lot of inflammation.
And voila, you have a yeast infection.
This condition is also known as vulvovaginal candidosis, vulvovaginal candidiasis, or vaginal thrush. The main species that causes vaginal yeast infection is Candida albicans [1], [3], [4]. Other Candida species like C. glabrata, C. tropicalis, C. krusei, and C. parapsilosis can also cause infection, but this is more common in women with chronic conditions like type 2 diabetes [5]–[7].
Have a yeast infection? You’re not alone
Yeast infection is the second most common vaginal infection in women (the first one is bacterial vaginosis). Here are some statistics:
- About 70-75% of women have a yeast infection at some point in their lives.
- About 10-14% of pregnant women have yeast infection at some point during pregnancy. This is more common to occur in the third trimester [8]–[10].
- And about 8% will have more than four episodes per year, that is, a recurrent or persistent yeast infection [1], [11].
What does a vaginal yeast infection look like?
Now let’s take a look at the most common symptoms of a yeast infection:
- A thick, usually odorless, white vaginal discharge with a cottage cheese-like consistency
- Vaginal and/or vulvar itching
- Vaginal and/or vulvar irritation
- Inflammation
- Pain during sex or urination
These symptoms usually range from mild to moderate, and tend to be worse before the start of the menstrual period due to hormonal changes. Itching is one of the most reported symptoms. However, for species other than C. albicans, the symptoms may be non noticeable at all [12].
Apart from these physical symptoms, having a yeast infection can also negatively impact quality of life, especially if recurrent. This situation may create stress and anxiety, decrease self-esteem and confidence, and affect partner relationships.
Always get a proper diagnosis
As with other vaginal infections, looking just at the symptoms may not be enough for a correct diagnosis. Especially if you have mild symptoms that don't fit well in the typical description of yeast infection.
That is why a pelvic exam, a microscopic examination, and some other tests to rule out other infections may be of help [13]. Measuring vaginal pH also can provide useful information, as in yeast infection the pH tends to be less than 5.
If it isn’t possible to visit your provider, you may be prescribed an over-the-counter antifungal based on symptoms. If symptoms persist after one round of treatment, call your provider to be seen for an appointment as you may have a resistant yeast.
A lab test may be done to identify which Candida species is causing the infection and check for antifungal resistance, which can be especially useful in cases of recurrent yeast infection.
Lactobacillus may not be very protective against Candida
Lactobacillus are considered protective bacteria when it comes to vaginal health. Having high numbers of these species provides protection against infections like bacterial vaginosis and aerobic vaginitis. But for yeast infection, the picture is not so clear.
Turns out women with yeast infection have high numbers of vaginal Lactobacillus, comparable to those of healthy women [14]–[16]. This questions the protective role of Lactobacillus against Candida. A clue may lie in which dominant Lactobacillus species you have, but studies have reported contradictory results.
Most women with yeast infection have L. iners as the dominant Lactobacillus species [15]–[17]. This is not surprising, considering that L. iners appears to be less protective than other Lactobacillus and is frequently detected along with bacterial vaginosis-associated bacteria.
However, a couple of studies found that C. albicans detection was more frequent in women with a vaginal microbiome dominated by L. crispatus [18], [19].
Candida during pregnancy and its possible complications
There may be an association between yeast infection or asymptomatic carriage of vaginal Candida and preterm birth. But it’s not as clear as for other vaginal infections. Studies have found a tendency or a slight increase in the risk. Here are some examples:
- Two clinical trials suggested that treating asymptomatic women positive for vaginal Candida with clotrimazole reduced the risk of preterm birth [20], [21].
- One study reported a reduction in birth weight and a tendency to reduce preterm birth rates in asymptomatic women positive for vaginal Candida during the first trimester of pregnancy [22].
- Another study found no association between C. albicans alone and preterm birth, but did find an association between Ureaplasma parvum and C. albicans and increased risk of preterm birth [23].
Apart from this potential association with preterm birth, moms with vaginal Candida may pass these yeasts to the baby during birth [24], [25]. This may increase the risk of oral candidiasis or diaper rash during the first year of life [26].
The standard treatment for yeast infection is antifungals
As having Candida as part of your vaginal microbiome doesn’t necessarily mean yeast infection, detection in the absence of symptoms doesn’t necessarily require treatment with medications. If you would like to decrease your chances of passing Candida to your baby, always discuss with your provider to see if a treatment would be appropriate.
For symptomatic cases the standard treatment is antifungals. These medications come as creams, vaginal suppositories, and pills. These are some examples:
- Miconazole (Monistat®, Vagistat®), available as a cream
- Fluconazole, available as pills
- Clotrimazole, available as a cream and vaginal suppositories
- Nystatin, available as a cream and vaginal suppositories
The treatment duration will depend on the severity of your symptoms and whether you are pregnant or not. But treatment usually goes from 1 to 7 days.
If you are pregnant, it’s better to avoid oral antifungals like fluconazole, because some studies have suggested it may increase the risk of malformations in the baby [27]. So for pregnant women, vaginal creams or suppositories are more appropriate. If breastfeeding, fluconazole is considered safe for the baby [11].
Recurrent yeast infection requires longer treatment. One study reported that following a maintenance regimen with fluconazole during a whole year resulted in 77% of women disease-free [28].
Candida species different from C. albicans are often resistant to antifungals. For example C. krusei is intrinsically resistant to fluconazole [29]. It has also been shown to be resistant to clotrimazole, nystatin, and others [30]. C. tropicalis may also be resistant to different antifungals, such as clotrimazole, fluconazole, and nystatin [30]–[32].
This is why it’s super important to always consult your provider before taking any of these medications. If you have antifungal resistant Candida, using the wrong medication may lead to treatment failure and recurrence of the infection [33], [34].
What about alternative treatments for yeast infection?
If you google you’ll find some alternative treatments to get rid of yeast infection. After several failed courses of antifungals you may be tempted to try some of these. Are they safe? Do they work?
Let’s take a brief look at some of these treatments:
- Boric acid suppositories. This treatment has been shown to be an effective alternative to antifungals [35], [36]. One study of diabetic women with vaginal yeast infection compared fluconazole treatment against boric acid vaginal suppositories. Turns out the suppositories were better than fluconazole at achieving cure [7]. Although this may sound encouraging, the bad news is that for both treatments about 35% of women experienced recurrence [37]. An important note: pregnant women and women trying to conceive should not use boric acid suppositories.
- Tea tree oil suppositories. Laboratory and animal experiments have shown that tea tree oil (Melaleuca alternifolia) is a powerful antifungal against Candida yeasts [38]–[42]. Preliminary research in humans shows that tea tree oil suppositories are effective at reducing symptoms and decreasing the numbers of vaginal Candida [43], [44]. If you’re pregnant, ask your provider before trying tea tree oil suppositories.
- The Candida diet. This is a low-sugar anti-inflammatory diet that focuses on avoiding foods that may promote Candida growth. While this diet is popular, its efficacy on reducing vaginal Candida hasn’t been tested. The logic behind it is that Candida needs sugar to grow. Due to its restrictive nature, it may be a good idea to avoid this diet during times of high nutritional requirements, such as pregnancy and illness. Foods high in sugar like fruits and dairy provide essential vitamins and minerals for the correct development of the baby. If you’re pregnant and want to give it a try, please do so with the guidance of a nutritionist to make sure you fulfill all your nutritional needs.
Things you can do to keep those yeasts under control
There are some general rules that will help you maintain a healthy vaginal microbiome. You can check our guide on lifestyle and other vaginal interventions.
Now, we told you that vaginal Lactobacillus may not be very protective against yeast infection. But taking probiotics containing species like Lactobacillus rhamnosus could be helpful, especially if you have Candida in your gut. Scientists think the gut may act as a reservoir that contributes to recurrent yeast infection [45].
Stay alert on any changes in the color and quantity of your vaginal discharge, itching, and any other unpleasant symptoms. It is normal for your vaginal microbiome to vary during the menstrual cycle (if you are not pregnant) but any major change or unpleasant smell should be taken care of.
