HIV passes between people through blood and certain other body fluids, including semen, pre-seminal fluid, rectal fluids, vaginal fluids, and breast milk.
For transmission to occur, HIV present in these fluids must get into the bloodstream through a mucous membrane (found in the rectum, vagina, penis, and mouth), open cuts or sores, or by direct injection.1,2
The most common ways that HIV can be passed from person to person include:
- Having anal or vaginal sex with someone who has HIV without using condoms or medicines to prevent or treat HIV. Worldwide, most new HIV acquisitions occur through sex. Women are particularly at risk of acquiring HIV through heterosexual sex. Having another sexually transmitted disease (STD) may increase a person’s risk of getting or transmitting HIV. For more information, see the Centers for Disease Control and Prevention's STDs and HIV Fact Sheet.
- Sharing needles, syringes, or other injection drug equipment with someone who has HIV.
- Perinatal transmission, which refers to HIV transmission from mother to child during pregnancy, labor and delivery, or breastfeeding. Pregnant women with HIV can prevent perinatal transmission by taking anti-HIV drugs. Additionally, in areas of the world where infant formula and safe water are available, women with HIV are recommended to avoid breastfeeding their children. Read more about preventing perinatal transmission of HIV.
In very rare cases, HIV also can be transmitted through other means, including oral sex, biting, deep open-mouth kissing, and pre-chewed food. The only known cases of transmission through pre-chewed food are among infants and involved blood from a caregiver’s mouth mixing with the food before feeding it to the infant.3 HIV also can be acquired through donated blood products or organ or tissue transplants, but this is rare today because of testing of the blood supply and organ and tissue donations.
How is HIV not transmitted?
HIV cannot be transmitted by:
- Contact with saliva, tears, or sweat
- Shaking hands
- Sharing food utensils
- Swimming in the same pool
- Using the same toilet seats
- Bites from insects or other animals