A vaginal yeast infection is not technically contagious in the way a cold or the flu is, but it can be passed between sexual partners. It is not classified as a sexually transmitted infection (STI) because most yeast infections develop without any sexual contact at all. The yeast responsible, primarily Candida albicans, already lives in the vagina of roughly 10% to 20% of women without causing any symptoms. Problems start when something disrupts the natural balance and allows that yeast to overgrow.
That distinction matters. You don’t “catch” a yeast infection the way you catch an STI. But sex with someone who has an active infection does raise the risk of developing one yourself.
Why Yeast Infections Aren’t Classified as STIs
Yeast infections develop because of an internal imbalance, not because of exposure to an outside pathogen. The vagina normally contains both yeast and beneficial bacteria called lactobacillus. The bacteria keep yeast levels in check. When something disrupts that balance (antibiotics, hormonal shifts, a weakened immune system, high blood sugar), yeast multiplies and burrows deeper into vaginal cells, triggering the itching, burning, and discharge of an infection.
Because the yeast is already present in the body before any symptoms appear, the CDC does not classify vaginal yeast infections as sexually transmitted. The primary cause is overgrowth of your own flora, not transmission from another person.
How It Can Still Pass Between Partners
Even though yeast infections aren’t STIs, the yeast itself can transfer during vaginal, oral, or anal sex. If you have an active vaginal yeast infection, a male partner may develop a yeast infection on the penis, which can cause redness, irritation, and itching on the head of the penis or under the foreskin. A female partner is also at risk and should be tested if she develops symptoms.
Oral sex adds another layer. Performing oral sex on someone with a genital yeast infection can lead to oral thrush, a yeast infection of the mouth and throat. The reverse is also possible: someone with oral thrush can pass yeast to a partner’s genitals during oral sex.
There’s also the issue of passing an infection back and forth. If one partner gets treated but the other doesn’t realize they’re carrying the yeast, the treated partner can become reinfected during their next sexual encounter. This cycle is one reason some people struggle with recurring infections.
Does Your Partner Need Treatment?
Current CDC guidelines say that for uncomplicated yeast infections, treating a sexual partner is not necessary. The data don’t support routine partner treatment the way they do for bacterial STIs. Simply having Candida present without symptoms is not a reason to treat.
The exception is when a partner develops symptoms. A male partner with penile irritation, redness, or itching after sex should seek treatment. A female partner who notices her own symptoms of a yeast infection should be tested and treated if positive. And if you’re dealing with recurrent yeast infections (four or more in a year), it’s worth considering whether reinfection from a partner could be a factor, even though this isn’t the most common cause.
What About Towels and Shared Items?
Casual, non-sexual transmission is not a significant concern for adults. You’re unlikely to develop a yeast infection from a toilet seat, shared bedding, or a swimming pool. In young children, the caution is a bit different: if two children bathe together and one has a yeast infection, using separate washcloths is recommended. But for everyday household contact between adults, this isn’t something to worry about.
Reducing the Risk During an Active Infection
The simplest approach is to avoid sex while you have an active yeast infection. Beyond the transmission risk, sex during a yeast infection is often uncomfortable and can further irritate already inflamed tissue.
If you do have sex, condoms and dental dams offer some protection but aren’t fully reliable for preventing yeast transfer. The yeast can be present on skin that a condom doesn’t cover. Letting your partner know about the infection is important so they can watch for symptoms and get treated quickly if needed, which also helps prevent the back-and-forth reinfection cycle.
Once treatment is complete and symptoms have resolved, the risk of passing yeast to a partner drops significantly. Most uncomplicated yeast infections clear within a few days of starting antifungal treatment, so the window where transmission is a concern is relatively short.