Human immunodeficiency virus (HIV) is one of the most recently discovered viruses in the world, and we’ve learned a lot about it in the last 30 years. In that time, we’ve developed treatments that allow people with HIV to live long and healthy lives . Unfortunately, back when the virus was still new and misunderstood, a lot of myths about how it’s spread were flying around—and some have stuck. Here’s the real deal on how HIV is transmitted.

Myth 1: You can get HIV from kissing, sharing a drink, touching, sitting on a toilet, or a mosquito bite

HIV is not spread through saliva, by touching a person or object, or by insect bites. For HIV transmission to occur , there has to be a passage of one person’s semen, vaginal fluid, breast milk, or blood through another person’s mouth, vagina, anus, veins, or open wound. In the United States, the most common ways for HIV to spread are unprotected sex and injection drug use.

Myth 2: You can’t get HIV from oral sex

Oral sex isn’t as risky as vaginal or anal sex, but there is still some risk . Risk of HIV transmission increases if there are open sores on the genitals of the person receiving oral sex, or mouth sores, gum disease or recent dental work for the person giving oral sex. Condoms and dental dams reduce the chance of giving or getting HIV during oral sex.

Myth 3: Women can’t give men HIV

While it is more difficult for a woman to give a man HIV, it’s not impossible. Compared to the vagina, there are fewer areas on the penis where the virus can enter the body. HIV can enter through the opening of the penis (urethra), where there’s a delicate kind of skin called a mucous membrane. The virus can also enter through cuts or sores on the penis.

It’s true that a woman is at higher risk of getting HIV from a man, because the vagina is all mucous membrane—which makes a larger area for HIV to enter the body. Also, semen may stay in the vagina for days, which increases exposure to the virus.

One complicating factor changes both men’s and women’s risk of getting HIV. When someone has a sexually transmitted infection (STI) like chlamydia, gonorrhea, or syphilis, the risk of getting or giving HIV increases significantly. These infections make it more likely for a person with HIV to shed the virus . They also make it more likely that a person exposed to the virus will be infected.

Myth 4: When a man is circumcised, he cannot get HIV

You may have heard about research showing that circumcised men had a significantly lower risk of getting HIV than non-circumcised men. Being circumcised reduces the risk of a man getting HIV from a woman by about 60-70%, but it doesn’t eliminate the risk completely. The benefit among men who have sex with men is uncertain. If a man has HIV, being circumcised has not been shown to reduce the risk of passing HIV onto a partner.

Myth 5: I’m straight and I don’t inject drugs, so I won’t get HIV

Although HIV was first recognized in the U.S. among men who sleep with men, the virus can and does spread through heterosexual sex. Like all other STIs, the risk of being exposed to HIV increases with the number of sexual partners.

For more evidence-based information about how HIV can be transmitted, check out Avert . Stay tuned for more information about how to get tested for HIV—coming soon!