1. Herpes
Herpes may be incurable, but it doesn’t make you a pariah. In fact, it kind of makes you normal. Around two-thirds of the world’s population under the age of 50 has herpes simplex 1 (HSV-1), which is known as the oral kind of herpes, according to the World Health Organization. And around one in every six Americans under the age of 50 has herpes simplex 2 (HSV-2), what’s known as the genital kind of herpes, according to the Centers for Disease Control and Prevention.
The thing about HSV-1 is that it sometimes creates cold sores in and around the mouth. “If you’re kissing someone with lesions in their mouth, mucous membranes make herpes easy to transmit,” Idries Abdur-Rahman, M.D., a board-certified ob/gyn, tells SELF. So, if someone you’re kissing has HSV-1, they could give you the virus (even if they aren’t currently experiencing an outbreak, a phenomenon known as ‘asymptomatic shedding’ means they can still transmit it, says Abdur-Rahman). And if they go down on you, they could transmit the virus to your genitals.
If you or your partner has cold sores, over-the-counter medications like Abreva can shorten the outbreak. There are also antiviral medications like Valtrex that people can take on a regular basis to prevent outbreaks from occurring.
2. Syphilis
“Syphilis is a highly infectious condition, and one of its hallmarks is the development of sores in the mouth,” board-certified ob/gyn Antonio Pizarro, M.D., tells SELF. The sores, which are usually round and open, “combine to make syphilis transmissible through kissing,” says Pizarro. Kissing isn’t the most common way to transmit syphilis—oral, anal, and vaginal sex still rank higher. But syphilis rates are currently on the rise, according to the CDC, so it’s good information to have. If you or your partner has syphilis-related sores in your mouth, they (and the virus itself) should clear up with the help of doctor-prescribed antibiotics.
So, what about other STIs? While the chances of passing infections like gonorrhea, chlamydia, and HIV through saliva aren’t usually worth worrying about, that changes if one of you has a cut or sore in your mouth. “Any time there’s an open sore and/or blood present, theoretically an infection could be transmitted orally,” says Pizarro.
3. Meningitis
Some meningitis is caused by bacteria while other cases come about because of viruses (including the herpes virus), Chris Carpenter, M.D., section head of Infectious Disease and Internal Medicine at Beaumont Hospital in Royal Oak, Michigan, tells SELF. Close contact with a person who has viral meningitis can result in you getting the virus, but it’s unlikely to actually turn into meningitis, according to the CDC.
Bacterial meningitis is usually the kind associated with outbreaks because the bacteria can be spread through close contact, including kissing, but unlike with the viral variety, the bacteria is more likely to cause meningitis in the host, says Carpenter. Symptoms include a stiff neck, fever, and headache, according to the CDC. “If we are aware of an outbreak, we will give people who have had close contact with the [infected person] antibiotics to protect them,” says Carpenter.
4. Infectious mononucleosis
The so-called “kissing disease”! It definitely deserves its nickname, because mono is caused by a virus that is easily transmitted through kissing, according to Mayo Clinic. One of its trademark signs is intense fatigue, although others include a sore throat and swollen lymph nodes. According to Mayo Clinic, “treatment mainly involves bed rest, good nutrition and drinking plenty of fluids,” so that’s basically the only potential benefit of getting mono.
5. Gingivitis
Kissing doesn’t just involve swapping spit—although, how unsexy does that sound when you’re not actually doing it?—it also includes exchanging bacteria with the other person. Depending on both of your oral healthcare habits, that bacteria can cause gingivitis, which is a mild form of gum disease. (It can also cause cavities.) “We each have our own natural bacterial flora in our oral environments. When someone has poor hygiene, certain bacteria in and around the gum tissue can become overwhelming,” Tim Pruett, D.M.D., founder of Flossolution, tells SELF.
They can pass that bacteria to you via kissing, which can potentially result in the typical inflamed, red gums that signal gingivitis, says Pruett. The best way to protect yourself is by maintaining excellent oral healthcare (i.e. brushing twice a day and flossing before bed) so no matter what kind of bacteria someone’s introducing into your mouth, you’re on it before it can grow out of control.
Zika is on the tip of everyone’s tongue right now, primarily because it can cause microcephaly, a birth defect marked by an abnormally small head and brain. Now, researchers are tasked with determining all the ways the virus can spread, including sexually. And yes, that may include saliva. “Mosquitoes are far and away the main root of transmission,” says Carpenter. “But we have also discovered that it is present in a number of different bodily fluids.”
There have been no known cases of Zika transmission through saliva, says a recent case study published in the New England Journal of Medicine. But when investigating one sexually-transmitted case of the virus, researchers said they “cannot rule out the possibility that transmission occurred not through semen but through other biologic fluids, such as pre-ejaculate secretions or saliva exchanged through deep kissing.” It’s a good thing to keep in mind, especially if you’re traveling to a Zika-affected area this summer. Now that you know how to stay safe when kissing, you can check out the next step—learning how to kiss someone.