“I Keep Getting Yeast Infections From My Boyfriend!”

Many people are familiar with this worst of feelings, that telltale prickle percolating deep in your business you just immediately know will blossom into a full-blown yeast infection by morning. It is, to put it as mildly as possible, hell; that excruciating and unscratchable itch. Some people are lucky and only develop vaginal yeast infections after a long day at the beach, or when they sports too hard in sweaty, skintight spandex. But there exists another camp, a less fortunate camp, of people who seem to always get a goddang yeast infection after they have sex.

Understandably, this leaves a lot of sufferers unspeakably frustrated, because sex and orgasms are good, healthy things many of us want to have on the regular. Nothing kills the mood quite like the specter of itchy yeast hanging over your bed. So: Why do some people always get yeast infections after sex?

All vaginas house yeast, a fungus called Candida; the problem arises when something throws the delicate vaginal ecosystems out of whack and Candida starts growing like crazy. Then, you're (often but not always) left with the characteristic white, cottage cheese-textured discharge; the inflamed, irritated labia; a possible bread factory smell wafting from down below; and that deep, deep itch the Centers for Disease Control and Prevention (CDC) estimates roughly 75% of U.S. women will experience at least once in their lifetime. An unfortunate 40 to 45% will have two or more Candida outbreaks.

Ask pretty much any vagina-having person you know, and many of them will report intimate familiarity with what they deem to be overenthusiastic yeast. And indeed, there exist a few reasons why a chronically itchy vagina might frequently follow sex.

According to obstetrician and gynecologist Dr. Sheila Loanzon, M.D., new sex partners, oral sex, antibiotics, and lube can all cause vaginal irritation, but the angry vaginas many people attribute to an overabundance of yeast may actually be symptomatic of something else.

"It is actually much more common for women to get bacterial vaginosis (BV) infections when they have intercourse instead of yeast infections," Loanzon tells Bustle. "This is due to the ejaculate or lubricant causing a change in the delicate pH balance of the vagina."

What Is Bacterial Vaginosis?

Often billed as a sexually transmitted infection, a label that doesn't quite fit, BV can result any time the vagina's bacterial balance gets upset and the bad bacteria overgrow the good. Although this is more apt to happen in people who are having sex with a new partner or multiple partners, BV is also linked to douching, and presents with the same key complaint that characterizes candida: a painful and/or burning itch in and around the vagina. What sets BV apart is the strong, fishy odor it gives the vagina. You might also experience a burning sensation when you pee, or notice a thin white or gray vaginal discharge in your underwear.

BV and yeast infections both qualify as vaginitis, or irritation of the vagina and vulva, and it's possible that both could result from PIV intercourse. "There are some studies that strongly support transmission of bacteria of the male to female during intercourse which lend to an increase of bacteria therefore leading to BV," says Loanzon.

But it's also possible to get yeast infections from a partner — because candida can and does live in your mouth and on penises, in addition to making a home in your vagina — and according to Loanzon, people with recurrent yeast infections (four or more in a year) may be contracting their particular yeast strain from their partner. (They may also have diabetes, HIV, or be pregnant.)

So if you're having sex with one person and finding yourself always on the losing end of a battle with vaginal yeast, it's possible you and your partner just keep swapping this candida plague back and forth. It's also possible you (or, heck, even a medical professional) have diagnosed yourself with a yeast infection when what you really have is BV, and so the symptoms are not going away; indeed, they may be continually reawakened by the sexual practices that throw off vaginal pH.

How To Save Your Vagina From Post-Sex Itch Storms

Loanzon recommends switching to condoms, if you suspect PIV sex is the culprit, and water-based lubes — "not fancy designer lubricant brands that cause explosions on the TV commercials," she says. Often, it will help to identify the vaginitis trigger, whether that's semen, lube, certain condoms, a particular kind of underwear. If you know what sends your vagina into an itch spiral, it's easy enough to eliminate those factors from your lifestyle. But your treatment quest shouldn't end with at-home experiments.

"Women are often misdiagnosing their vaginal infections so it is important to be seen by a health care provider to confirm which infection they have," Loanzon says. "Notoriously, both women and providers diagnose the wrong infection based on symptoms alone." She encourages an in-person examination of the affected area using a microscope to determine the cause of vaginitis and, relatedly, the appropriate medication course.

Yeast infections may be treated with a topical or oral anti-fungal; BV, meanwhile, requires antibiotics, either oral or topical. But because these antibiotics wipe out your vaginal bacteria, they may create an environment primed to disrupt your yeast balance, leading to — you guessed it — a yeast infection following close on BV's tail. You're going to want to secure medication to cure all your vaginal ailments, trust me.

Regardless, though, you may find that what you thought was a yeast infection flaring up every time you get busy is actually untreated BV (or, actually, an STI called trichomoniasis). You won't return from your itchy sexual hellscape until you get the correct diagnosis, though, so definitely consult a doctor in person, at your earliest convenience. Your vagina will thank you.

Expert:

Dr. Sheila Loanzon, M.D., OB-GYN