Genital yeast infections are not sexually transmitted diseases, but they can be transmitted sexually. Does that sound confusing? Keep reading anyway, because most women have a yeast infection at least once in their lifetimes — and nobody likes the idea of that yeast infection spreading to a partner.
So, does that mean you have to stock up on natural or pharmacological yeast infection treatment at home any time your partner has one?
What Is Genital Candidiasis?
Genital yeast infections are typically associated with women — no surprise, since around 75 percent of all women will have at least one yeast infection! Nonetheless, yeast infections in men do exist.  Genital candidiasis is an overgrowth of a fungus naturally present in and on the body in smaller quantities. Candida albicans is to blame in over 80 percent of all yeast infection cases, but other yeast species, including Candida glabrata and Candida parapsilosis, can cause yeast infections as well. [2,3]
How Do You End Up With A Yeast Infection?
Research shows that the risk factors for vulvuvaginal candidiasis, or vaginal yeast infections, are rather varied:
- Condom use
- Recent antibiotic use
- Being of reproductive age
- Being pregnant
- Using hormonal contraception
- Interestingly, not having gonorrhea or bacterial vaginosis
- Having sexual intercourse more than four times a month [4, 2]
Yeast infections in men are much less researched than yeast infections in women, but the identified risk factors include being older than 40, having diabetes , not being circumcised , and, interestingly, being heterosexual and recently having had vaginal sexual intercourse with a woman .
Wow, Does That Mean Yeast Infections Are A Sexually Transmitted Disease?
Sexually transmitted diseases are those diseases that are spread through sexual contact. You know, things like chlamydia, gonorrhea, genital herpes, syphilis, and trichomoniasis . Genital yeast infections are not considered a sexually transmitted disease, because numerous people — especially women — develop them without being sexually active. Someone who has never had sexual contact of any kind may develop a genital yeast infection after taking a course of antibiotics, for instance, as we already saw above.
One paper that focused on candida balanitis (male yeast infections with penile inflammation) and analyzed the available body of research on the topic found that:
- If one partner in a couple has a yeast infection, the other is very likely to have one as well — but fascinatingly, though both partners are colonized by the same yeast species (often candida albicans) in a quarter of these co-infection cases, the colony was found to be genetically similar only 17.2 percent of the time. That means their infections may not have been transmitted from one to the other.
- Approximately 39 percent of vulvovaginal candidiasis cases were estimated to be sexually transmitted, a very significant number.
- 29 percent of cases of candida balanitis were sexually acquired. 
That sounds like a pretty straightforward verdict, right? Huge numbers of genital yeast infections in both men and women were indeed sexually acquired! Another study, this time of the partners of women who either had an acute vaginal yeast infection or recurrent yeast infections, supports the idea that yeast infections are often sexually transmitted:
- The mouths of guys whose partners had vaginal candidiasis tested positive for a Candida colonization in 23.2 percent of cases.
- Candida colonization was found on the base of the glans penis in 16 percent of cases.
- The seminal fluid of 14.4 percent of the men were found to be positive for a Candida colonization. 
Got It — Genital Yeast Infections Can Be Sexually Transmitted: What Now?
We haven't mentioned the symptoms of vaginal yeast infections and penile yeast infections yet. Most women, of course, are familiar with them already: vaginal and vulval itching, burning, soreness, redness, and a thick, white, cottage-cheese-like vaginal discharge . Men, conversely, are more likely to experience a sore, red, and itchy penis with scaly skin and a skin rash. Their penis may also become swollen (inflamed). 
That's a particular problem because the antifungal medications most commonly used to treat genital yeast infections are available over the counter, so if you wrongly think you have a yeast infection, you may self-treat with the wrong medication without ever seeing a doctor. Anyone who notices anything "off" about their genitals should seek medical attention to obtain the correct diagnosis (or diagnoses, of course). This is the only way to make sure you're accessing the correct treatment for the problem you actually have.
Knowing that yeast infections can be sexually transmitted does have another very important purpose, however. If your partner has recently been diagnosed with vulvovaginal candidiasis or has recurrent vaginal yeast infections, or if your partner has recently been diagnosed with candida balanitis or a male yeast infection, it's important that you get tested yourself, too. Yup, even if you don't have any actual symptoms, since it is quite possible to have asymptomatic candidiasis . Doing so may prevent a lot of hassle — or should I say, a lot of itching, burning, redness, and soreness?