What Is a Yeast Infection, Exactly? A Gynecologist Weighs In

This informational guide, part of POPSUGAR's Condition Center, lays out the realities of this health concern: what it is, what it can look like, and strategies that medical experts say are proven to help. You should always consult your doctor regarding matters pertaining to your health and before starting any course of medical treatment.

Maybe you sat around too long in a wet swimsuit or just finished a round of antibiotics. First, you notice the itching. You may brush it off as nothing until you spot the thick, white discharge — a telltale symptom of a yeast infection. "Most women have one [yeast infection] during their lives, and some have many," says Alyssa Dweck, MD, a gynecologist and author of "The Complete A to Z for Your V". Being common doesn't make them less annoying, though. Here's everything you need to know about what causes yeast infections, the best ways to treat them, and how to keep them from coming back.

Alyssa Dweck, MD, is a gynecologist and author of "The Complete A to Z for Your V".

A yeast infection is "a fungal infection that causes irritation, discharge and intense itchiness of the vagina and the vulva — the tissues at the vaginal opening," according to the Mayo Clinic. About 75 percent of people with vaginas in the US will have at least one yeast infection in their lifetimes, per the Centers for Disease Control and Prevention (CDC), and about 45 percent will have two or more.

Additionally, about 138 million people with vaginas worldwide have recurrent yeast infections — three or four a year — and the highest prevalence is among those 25 to 34, according to an international study published in The Lancet in 2018. Recurrent yeast infections can take an emotional toll, the researchers said, affecting self-esteem and confidence and interfering with people's sex lives and their ability to do physical activity.

Itching accompanied by a thick, white vaginal discharge is the cardinal sign of a yeast infection (aka vulvovaginal candidiasis), Dr. Dweck explains. These infections are also often accompanied by a burning sensation and redness around the vaginal opening and vulva. "The itching can be intense, and you might feel it internally, at the opening of the vagina, or on the skin of the vulva," Dr. Dweck tells PS. "It can be horribly uncomfortable and can cause physical and emotional distress." A full list of symptoms, per the Mayo Clinic, can be found below:

Those irritating symptoms start because the billions of bacteria and yeast that live naturally in the vagina — known as the vaginal microbiome (yes, the vagina has a microbiome, too!) — are thrown out of whack, and a certain type of yeast, usually Candida albicans, grows out of control. "A lot of factors can trigger yeast overgrowth," Dr. Dweck says. They include:

Fortunately, the process of diagnosing a yeast infection is pretty straightforward. Your provider will typically go over you medical history, discussing symptoms and changes to your health, per Yale Medicine. Then, they'll do a pelvic exam, focused on the vulva and inside the vagina to assess redness, inflammation, and discharge. From here, a diagnosis may be made or they'll swab the area to collect a lab sample for further confirmation, according to Yale Medicine.

If you're having symptoms of a yeast infection for the first time, you might be tempted to self-diagnose it and try an over-the-counter yeast-infection treatment. Don't. "It's a good idea to have your doctor confirm that it's yeast, because if you use a yeast treatment for another type of infection, like bacterial vaginosis, which causes similar symptoms, it won't work, and your condition could get worse," Dr. Dweck says. If your symptoms are severe, like the skin on your vulva is inflamed and splitting, it's time to see your doctor, too.

Medications come in a variety of forms, including creams, vaginal tablets, suppositories, and oral pills — and are available over the counter. Look for an antifungal medication that contains miconazole, clotrimazole, tioconazole, or butoconazole, which stop the growth of the yeast that's causing the infection. "Most infections caused by Candida albicans respond well to treatment," Dr. Dweck says. "Just make sure you use the medication for the recommended period of time."

To prevent a recurrence, keep your genital area dry, wear cotton underwear, avoid douching (which removes healthy bacteria from the vagina), eat yogurt with live cultures to keep your vaginal microbiome healthy, and take Lactobacillus acidophilus (the vagina's primary protective bacteria) tablets when you have to take antibiotics.

But if you're one of the people who experience three or more yeast infections a year, consider bringing it up with your ob-gyn. "Recurrent yeast infections are often caused by a different, treatment-resistant strain of yeast," Dr. Dweck says. "See your doctor, who can identify the source of the problem and prescribe an effective treatment."

Ginny Graves is an award-winning writer in the San Francisco Bay Area whose work focuses on science, psychology, health, nature, and the human-animal bond. In addition to PS, her features have appeared in Time, Vogue, Runner's World, Men's Health, O The Oprah Magazine, Elle, Prevention, Scientific American, and National Geographic Adventure.