How Do You Get Yeast Infections?

Vaginal yeast infections are a common issue that many women face, and understanding how they develop can help you prevent and manage them more effectively. But other than bad luck, how do you get yeast infections?

Let’s dive into what causes yeast infections and some common factors that might contribute to getting one.

What is a yeast infection? 

A yeast infection, also known as vaginal candidiasis, is a type of fungal infection caused by an overgrowth of a type of fungus called Candida. 

While Candida is normally present in small amounts in the vagina, mouth, and digestive tract, an imbalance can cause it to multiply and lead to an infection. The most common culprit is the fungus Candida albicans.

Up to 90% of yeast infections are caused by Candida albicans, but other strains can overgrow in the same way. These include C. glabrata, C. tropicalis, C. parapsilosis, and C. krusei, among others. 

Vaginal yeast infections are incredibly common. Up to 75% of women will have a vaginal yeast infection at least once in their lifetime. 

Common symptoms of a yeast infection include:

• Vaginal and vulvar itching and irritation
• A burning sensation, especially when you pee or have sex
• Redness and swelling of the vulva
• Thick, white discharge that looks like cottage cheese. 

Other vaginal infections — including bacterial vaginosis (BV) — can cause similar symptoms, such as unusual vaginal discharge. Vaginal yeast infections also share symptoms with the sexually transmitted infection (STI) chlamydia, so it's important you see a healthcare provider to get an accurate diagnosis if you think you have a yeast infection.

What causes a yeast infection?

The cause of a yeast infection is yeast overgrowth, but several factors can disrupt the natural balance of yeast and bacteria in your vagina, leading to a yeast infection. 

Antibiotics 

While antibiotics can be really helpful for knocking out bacterial infections, they can also reduce the number of healthy bacteria in your vagina that keep yeast levels in check. This imbalance can allow yeast to overgrow.

Antibiotics are the most common and predictable cause of yeast infections. Several studies have found a clear link between antibiotic use and Candida overgrowth, but the exact reasons remain unclear. People who already have healthy levels of Candida in their vaginal microbiome are at a higher risk of developing a vaginal yeast infection after taking antibiotics.

High estrogen levels

The hormone estrogen can play a role in the development of a vaginal yeast infection because it can alter the balance of yeast and good bacteria in your vagina. 

Estrogen increases the production of glycogen in the vaginal walls. Glycogen is a form of sugar, and higher levels of glycogen provide more food for yeast, specifically Candida, which can lead to overgrowth and infection. 

Fluctuations in estrogen levels can also disrupt the vaginal pH balance and the body’s immune responses. This disruption can reduce the effectiveness of the body’s natural defenses against the overgrowth of yeast.

Vaginal yeast infections are more common when estrogen levels are higher, for example in pregnancy, in certain phases of the menstrual cycle, when taking birth control pills. In perimenopause and postmenopause, patients that take menopausal hormonal therapy may get more yeast infections as well.

Weakened immune system 

If your immune system is compromised due to illness (such as an HIV infection), medication, or stress, it can be harder for your body to control yeast growth.

A strong immune system helps keep the growth of Candida in check. When the immune system is weakened, whether due to illness, medication (like chronic steroids), or other conditions, it can't effectively control the proliferation of Candida, allowing it to overgrow and cause an infection. 

Additionally, the immune system plays a crucial role in maintaining the balance of microorganisms in the body, including the normal bacterial flora in the vagina. When it is compromised, it can’t adequately support the "good" bacteria that normally suppress Candida growth. This disruption can lead to an imbalance, favoring yeast overgrowth.

Sex 

While yeast infections aren’t classified as sexually transmitted infections, sex can trigger the onset of a yeast infection. This happens for several reasons. 

The vagina has a delicate pH balance that helps keep harmful bacteria and fungi in check, but semen (which is slightly alkaline) can disrupt this balance, giving yeast a chance to overgrow. 

Additionally, penetrative sex can sometimes cause minor irritation or tiny tears in the vaginal lining, making it easier for yeast to grow, especially if there's already a slight imbalance. 

The products you use during sex play a role, too. Some lubricants and condoms contain ingredients that might irritate the vagina or alter its natural flora, creating a more favorable environment for yeast growth. 

In some cases, yeast infections can also be transmitted between partners. If vaginal fluids are exchanged, there's a small risk of transmitting yeast infections. Men can get a penile yeast infection and pass it on to their female partners if they have unprotected sex with an active yeast infection.

Uncontrolled diabetes

Having uncontrolled diabetes increases your risk of vaginal yeast infections due to high blood sugar levels. Yeast, particularly Candida, thrives on sugar, so elevated blood sugar provides an ideal environment for yeast to grow and multiply.

Additionally, diabetes can compromise your immune system. When your blood sugar is high, it can impair the ability of your immune cells to function properly. This weakened immune response makes it harder for your body to fight off infections, including those caused by yeast.

Vaginal yeast infection treatment

Most vaginal yeast infections clear up with over-the-counter antifungal treatments. These come in the form of creams, ointments, or suppositories.

For persistent or recurrent yeast infections, it’s best to see your healthcare provider for an accurate diagnosis and stronger prescription treatments.

The treatment plan, including how much medication you take, how long you take it, and how effective it is, will depend on the specific strain causing the yeast infection, how severe your symptoms are, and your overall health. So, your doctor might suggest different treatment options, like a longer course or a stronger dose, or even combining different treatments to get the best results.

FAQ

What is the main cause of a yeast infection? 

The main cause of a vaginal yeast infection is an overgrowth of the Candida fungus (especially Candida albicans), which normally lives in the vaginal microbiome in small amounts. This overgrowth happens when something disrupts the natural balance of healthy bacteria and yeast in the vaginal environment. For example, antibiotic use, hormonal fluctuations, high blood sugar levels, a weak immune system, and sexual activity. When this balance gets thrown off, Candida can multiply too much, leading to the uncomfortable symptoms of a yeast infection.

Can a man give a woman a yeast infection? 

Yes, a man can pass a vaginal yeast infection to a woman, although it's not very common. Yeast infections aren't considered sexually transmitted infections, but the fungus Candida can be transferred between partners during sex. If a man has a yeast infection on his penis, he could potentially share the Candida with his sexual partner through unprotected sex. Even if a man doesn't have an active yeast infection but carries Candida on his skin, it might contribute to upsetting the balance in his partner's vaginal microbiome. This is especially true if she's already prone to yeast infections due to factors like antibiotics, hormonal changes, or a weakened immune system. To prevent vaginal yeast infections it's smart to use protection during sex.