If you’ve spent enough time on TikTok, Reddit, or deep in the world of internet sex slang, chances are you’ve come across the term “rainbow kiss.” And if your immediate reaction was “Wait…what is happening here?” you’re definitely not alone. The rainbow kiss meaning isn’t exactly self-explanatory, and despite the colorful name, it refers to a very specific sex act involving oral sex, menstruation, semen, and kissing.

More specifically, Carol Queen, PhD, staff sexologist at Good Vibes, explains that a rainbow kiss typically happens when two consenting partners perform oral sex on each other while one person is menstruating, then kiss afterward, exchanging fluids in the process. The act is generally considered a form of fluid play, a broader kink category involving things like blood, semen, spit, or sweat.

While rainbow kisses are definitely more niche than, say, your average quickie or shower sex fantasy, sex educators say conversations about them can still be useful. Talking openly about fluid play, period sex, and kink helps normalize discussions around consent, STI testing, boundaries, and sexual preferences that don’t always fit into the standard “vanilla sex” mold.

“By challenging societal taboos and misconceptions surrounding kink, individuals can feel more empowered to explore their desires safely, communicate boundaries effectively, and engage in consensual and fulfilling sexual experiences without fear of judgment or discrimination,” says sex educator Topaza Yu.

Ahead, experts break down what a rainbow kiss is, why some people are into it, and the safety precautions worth knowing before trying any kind of fluid play.

What Is a Rainbow Kiss?

Rainbow kisses are generally considered a form of fluid play, a type of kink involving (you guessed it) bodily fluids. In practice, the act is essentially a variation of 69-ing that combines oral sex, period sex, and kissing, with partners exchanging menstrual blood and semen afterward.

Wendasha Jenkins Hall, PhD, founder of The Sensible Sexpert, explains rainbow kisses likely evolved from oral-based period sex. “You’ve heard the term ‘running the red light?’” she says, referring to having sex while a partner is menstruating. “This is a level up from that.”

While rainbow kisses definitely aren’t the most mainstream sex act around, Hall says they can appeal to people interested in fluid play, period sex, or bodily fluid kinks more broadly. And no, the colors involved don’t exactly create a literal rainbow. But according to Babeland sex educator Lisa Finn, the name has still stuck over the years.

What Is a Fluid Fetish?

As mentioned, rainbow kisses generally fall under the broader umbrella of fluid play, a kink category involving bodily fluids. Queen explains that people with fluid fetishes may be aroused by the sight, feel, taste, or exchange of bodily fluids during sex. Like most kinks, the appeal can vary widely from person to person.

And fluid fetishes aren’t limited to the fluids involved in rainbow kisses. Some people may be into spit, sweat, urine, breast milk, semen, or menstrual blood, while others are drawn to more specific forms of fluid play like golden showers. The intimacy and vulnerability associated with fluid exchange draw some, Finn says, while others are more interested in the physical sensations or the taboo aspects of the experience.

Or, as Tim Lagman, a certified sex educator with the American Board of Sexology, puts it, “Some people have a fluid fetish simply because it feels good. The warm fluid on your skin or how it feels in your mouth can be comforting and enjoyable.”

Ultimately, Finn stresses that “as long as it’s fully consensual and everyone is risk-aware,” there’s no right or wrong reason to be interested in fluid play or explore a fluid fetish with a partner.

Rainbow kisses tend to spark strong reactions online. One doctor on X even bluntly advised, “Pls, don’t ever do it.” But experts say the real concern isn’t the act itself so much as the potential health risks that come with exchanging bodily fluids during sex.

“Semen and period blood can carry lots of different infectious particles, such as HIV, syphilis, and hepatitis,” says ob-gyn Heather Irobunda, MD. “If you are unsure of your partner’s STD status, you should not be sharing rainbow kisses.”

Hall stresses that it’s not enough to get tested once if you’re regularly engaging in sex acts involving fluid exchange. “When I say tested, I mean continually tested every three to six months,” she explains. “But if all partners are actively testing and they understand the boundaries and offer their consent, then it’s typically safe.”

Consent and communication are also especially important when exploring any kind of fluid play, Hall adds.

“[Rainbow kisses are] typically done among partners who take these safety precautions,” she explains. “They’re not done with a person on the street or a person on an app. There has to be consent around what’s going on, there have to be limitations, and there have to be hard boundaries because of the disease and illness factors.”

Yu agrees, adding that safer sex practices are crucial for protecting both yourself and your partners from STIs and unintended pregnancy.

How Is a Rainbow Kiss Performed?

While some people describe rainbow kisses as something that can happen spontaneously during oral sex and period sex, experts say communication and planning are pretty important if both partners actually want to try it intentionally.

For starters, both people need to be comfortable with the exchange of bodily fluids involved and willing to discuss boundaries beforehand. Timing also matters.

“The trick is for you and your partner to finish at about the same time, so that neither of you has to hold the blood or semen in your mouth too long,” explains Danyell Fima, co-founder of Velvet Co. “You’ve really got to know your body and know your partner.”

Hall adds that safer sex precautions are especially important during any type of fluid play. One major tip? Avoid brushing or flossing your teeth immediately beforehand, since tiny cuts or abrasions inside the mouth can actually increase the risk of STI transmission.

“If you have those micro-abrasions and you go down on someone and you come in contact with semen, bodily fluids, or blood, that is a way that HIV and hepatitis, and even chlamydia or gonorrhea, can be transmitted,” Hall explains.

Her advice: Wait until afterward to brush your teeth, and rinse with an antiseptic mouthwash first. Lagman also recommends avoiding fluid exchange if either partner has open cuts, wounds, or active cold sores, since those can increase the risk of infection as well.

Why Are Some People Into Rainbow Kisses?

According to Sadie Allison, PhD, founder of TickleKitty.com, rainbow kisses can appeal to people who already enjoy period sex, fluid play, or forms of intimacy that feel especially vulnerable and taboo.

And while period sex was once treated as something dirty or off-limits, Hall says attitudes around it have shifted significantly in recent years. "Now we’re actually starting to see that there are benefits, like relieving stress or pain from headaches or menstrual cramps,” she explains.

For some people, the appeal is emotional or psychological as much as physical. Fima, for example, describes rainbow kisses as the pinnacle of showing comfort with and respect for your partner’s body and your own. “It’s a great way for everyone to enjoy the few minutes of cathartic bliss right after you both orgasm,” she adds. “Consider that the goal.”

Others may simply enjoy the taboo, sensory, or trust-based aspects of fluid play. Hall notes that some people are specifically interested in blood play, while others are drawn to the intimacy and vulnerability involved in exchanging bodily fluids during sex.

“Coming into contact with the taste of it, the smell of it, that’s often what turns people on,” Hall explains. Ultimately, Allison says rainbow kisses are no different from many other consensual kinks people choose to explore together. “Like the hundreds of other fetishes out there, this unique activity is perfectly okay to do so long as it’s agreed upon by two consenting adults.”

Is There a Good Rainbow Kiss Alternative?

If you find the idea of a rainbow kiss intriguing but aren’t totally sure you want to dive in headfirst, experts say there’s nothing wrong with easing into different forms of fluid play gradually.

“Try experimenting with only a drop of semen and/or blood and a light peck before going to a full makeout session,” says Lagman. “Slowly work your way up to more fluids and messier play.”

Another option is to simply simulate the experience instead of using real bodily fluids. Finn says some people experiment with edible fake blood or lubricants designed to mimic the appearance and texture of semen to explore the sensory or psychological aspects of the kink in a lower-risk way.

“You can find fake edible blood at most Halloween stores, and conveniently enough, many hybrid lubricants kind of have a cum-like look to them already and are safe for oral, vaginal, and anal play,” Finn explains. “See how it turns you on before [or instead of] committing to the real thing.”

Ultimately, experts stress that there’s no “right” way to explore kink. The most important thing is making sure everyone involved feels informed, comfortable, and fully consenting throughout the experience.

What Else Do I Need to Know Before I Engage in a Rainbow Kiss?

Hall emphasizes the importance of taking precautions when performing any sex act involving bodily fluids, especially with a new partner. She also notes that period sex and oral sex don’t automatically have to involve a significant amount of blood, depending on the type of stimulation involved.

“It’s possible to perform cunnilingus on a menstruating person and not get blood in your mouth if you focus your attention on external stimulation,” Hall explains, pointing to areas like the clitoris or mons pubis. And if you’re worried about the potential messiness of period sex or fluid play in general, Hall recommends practical prep like laying down dark towels or sheets beforehand.

But beyond the logistics, one of the biggest issues surrounding kinks like rainbow kisses is the shame people often attach to them. “When we shame people, that’s how our activities become unsafe. We do them secretly, we don’t want to talk to our healthcare providers about them, we don’t want to go get tested,” she says. “If we’re open to more variations of sexual behavior, we can be safer.”

At the same time, experts stress that there’s absolutely nothing wrong with deciding a rainbow kiss is not for you. “As long as no one is being harmed, everyone is giving their consent, there are no children involved, there are no animals involved, then do you,” Hall says. “Do what makes you happy.”

And if nothing else, at least now you’ll know what people are talking about the next time “rainbow kiss” randomly shows up on your FYP.