• How Is HIV Transmitted?

Unprotected sex is the most common way people get infected with HIV in the U.S., followed by sharing needles.

Unprotected sexual contact:

HIV is primarily spread through unprotected sexual contact – vaginal, anal or oral sex. The chances of getting or passing HIV from oral sex are lower than vaginal or anal sex, but there is still a risk. Certain bodily fluids that can be shared during unprotected sex, such as pre-semen, semen, vaginal fluids or blood (including menstrual blood), can contain the virus.

In the genitals and the rectum, HIV may infect the mucous membranes directly or enter through cuts and sores caused during sexual intercourse. Vaginal and anal intercourse is a high-risk practice.

The mouth is an inhospitable environment for HIV (in semen, vaginal fluid or blood), meaning the risk of HIV transmission through the throat, gums and oral membranes is lower than through vaginal or anal membranes. HIV can be transmitted from pre-semen or semen coming into contact with oral problems, such as open sores or bleeding gums. Oral sex (mouth-penis or mouth-vagina) is considered a low-risk practice.

Direct blood contact:

Sharing injection drug needles, blood transfusions, accidents in health care settings or certain blood products may transmit the HIV virus. An injection needle can pass blood directly from one person’s bloodstream to another. It is a very efficient way to transmit a blood-borne virus. Sharing needles is considered a high-risk practice.


Women who are HIV positive can pass HIV to their babies before or during delivery or through breastfeeding after birth. While small amounts of breast milk do not pose significant threat of infection to adults, it is a viable means of transmission to infants. There are medications that can greatly reduce the chance of an HIV-positive mother passing HIV to her baby.

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