Although yeast infections are associated with sex, they are not usually considered to be sexually transmitted infections. That said, it may be possible for yeast infections to be transmitted during oral sex and other sexual activity. The data isn't clear, but it's considered far more likely for yeast infections to be caused by health concerns and behaviors other than sex.

As many as three-quarters of women will be diagnosed with a yeast infection at least once in their lives.

Yeast infections are skin infections that are caused by one or more species of yeast. Most often, they are caused by various Candida species, specifically Candida albicans.

However, there are more than 20 species of Candida that can cause yeast infections (also known as candidiasis). Oral candidiasis is generally known as thrush. It is vaginal candidiasis that is commonly referred to as a yeast infection.

vaginal yeast infection symptoms — © Verywell, 2018

Frequent Symptoms

Vaginal yeast infections are generally relatively mild infections. The symptoms are very recognizable and include:

Itching or soreness of the vagina
Pain during sexual intercourse
Pain or burning when urinating
Changes in vaginal discharge

With a more severe infection, there may be redness and cracking of the skin. This can be painful. However, for most people, itching is the main symptom of a vaginal yeast infection.

Oral yeast infections, or thrush, have slightly different symptoms. They usually do not cause itching. Instead, you may notice:

White patches in your mouth, on your tongue, or in your throat
Redness and soreness
Difficulty tasting things
A feeling like your mouth is full of cotton
Pain when eating or swallowing
Cracking and irritation around the corners of the mouth

Complications

Recurrent Infections

The most common complication of a yeast infection is another yeast infection. Research estimates that as many as a quarter of women who have one yeast infection will go on to have another within one year.

Recurrent yeast infections can be disruptive to a person's well-being, affecting how they feel about themselves and their bodies. They can also cause difficulties in a relationship if the yeast infections disrupt normal sexual activity.

Pregnancy Complications

For most people, yeast infections are an unpleasant but minor health concern. However, there is some evidence that vaginal yeast infections may sometimes cause problems with a pregnancy.

Pregnant women with yeast infections may be more likely to experience preterm labor, preterm rupture of membranes, or other problems. However, the research is not conclusive. Therefore, due to safety concerns about certain common yeast infection treatments during pregnancy, doctors may choose to just treat candidiasis symptoms rather than worry about eliminating a yeast infection.

When to See a Doctor

From an overall health perspective, yeast infections aren't that big of a deal. However, these infections can be very unpleasant. Therefore, most people will want to treat a yeast infection quickly in order to get rid of the symptoms.

If you suspect a yeast infection for the first time, you see a doctor for a diagnosis. That's true even though treatment is available over the counter. Unfortunately, it can be difficult to distinguish between a yeast infection and an STD just by the symptoms. You want to make certain you're treating the right thing.

Even if you've had a number of yeast infections, it's still good to go to a doctor to be certain of what is causing your symptoms. Many times, an over-the-counter yeast infection treatment isn't successful because you don't have a yeast infection. Resistance to treatment is also a possibility, but it's less common than for bacterial diseases.

Causes and Risk Factors for Yeast Infections