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Vaginal Sex and HIV Risk

Vaginal sex (intercourse) involves inserting the penis into the vagina. HIV can be transmitted during this activity if either partner has HIV. You can lower your risk for getting and transmitting HIV by using condoms the right way every time you have sex; taking daily medicine to prevent HIV, called pre-exposure prophylaxis (PrEP); and taking medicines to treat HIV if you have HIV, called antiretroviral therapy (ART).

Risk of HIV

Some sexual activities are riskier than others for getting or transmitting HIV. For an HIV-negative person, the riskiest activity for getting HIV is being the receptive partner (“bottom”) in anal sex. Being the insertive partner (“top”) in anal sex or having vaginal sex (insertive or receptive) is less risky, though either partner can get HIV through those activities as well.  Activities like oral sex, touching, and kissing carry little to no risk for getting or transmitting HIV.

  • A woman can get HIV during vaginal sex because the lining of the vagina and cervix may allow HIV to enter her body if her male partner’s body fluids carry HIV, including blood, semen (cum), and pre-seminal fluid (pre-cum). Using condoms or medicines to protect against transmission can decrease this risk.
  • Men can also get HIV from having vaginal sex with a woman who’s HIV-positive because vaginal fluid and blood can carry HIV. Men can get HIV through the opening at the tip of the penis (or urethra); the foreskin if they’re not circumcised; or small cuts, scratches, or open sores anywhere on the penis. Using condoms or medicines to protect against transmission can decrease this risk.

Risk of Other Infections

In addition to HIV, a person can get other sexually transmitted diseases (STDs) like chlamydia and gonorrhea from vaginal sex if condoms are not used correctly. Even if a condom is used, some STDs can still be transmitted through skin-to-skin contact (like syphilis or herpes). Hepatitis A and B can also be transmitted through vaginal sex. Getting tested and treated for STDs reduces a person’s chances of getting or transmitting HIV through vaginal sex. If one has never had hepatitis A or B, there are vaccines to prevent them. A health care provider can make recommendations about vaccines.

Reducing the Risk

Condoms and Lubrication

Latex or polyurethane male condoms are highly effective in preventing HIV and certain other STDs when used correctly from start to finish for each act of vaginal sex. People who report using condoms consistently reduced their risk of getting HIV through vaginal sex, on average, by 80%. Condoms are much less effective when not used consistently. It is also important that sufficient water- or silicone-based lubricant be used during vaginal sex to prevent condom breakage and tearing of tissue. Female nitrile condoms can also prevent HIV and some other STDs. Since condoms are not 100% effective, consider using other prevention methods to further reduce your risk.

PrEP

People who are HIV-negative and at very high risk for HIV can take daily medicine to prevent HIV called pre-exposure prophylaxis (or PrEP). If taken daily, PrEP is highly effective for preventing HIV from sex. PrEP is much less effective when it is not taken consistently. Since PrEP does not protect against other STDs, use condoms the right way every time you have sex.

PEP

Post-exposure prophylaxis (PEP) means taking antiretroviral medicines—medicines used to treat HIV—after being potentially exposed to HIV during sex to prevent becoming infected. PEP should be used only in emergency situations and must be started within 72 hours after a possible exposure to HIV, but the sooner the better. PEP must be taken once or twice daily for 28 days. When administered correctly, PEP is effective in preventing HIV, but not 100%. To obtain PEP, contact your health care provider, your local or state health department, or go to an emergency room.

ART

For people with HIV, HIV medicine (called antiretroviral therapy or ART) can reduce the amount of virus in the blood and body fluids to very low levels, if taken as prescribed. This is called viral suppression—usually defined as having less than 200 copies of HIV per milliliter of blood. HIV medicine can even make the viral load so low that a test can’t detect it. This is called an undetectable viral load. People who take HIV medicine as prescribed and get and stay virally suppressed or undetectable can stay healthy for many years, and they have effectively no risk of transmitting HIV to an HIV-negative partner through sex.  Only condoms can help protect against some other STDs.

Other Ways to Reduce the Risk

People who engage in vaginal sex can make other behavioral choices to lower their risk of getting or transmitting HIV. These individuals can:

  • Choose less risky behaviors like oral sex, which has little to no risk of transmission.
  • Get tested and treated for other STDs.

This page gives effectiveness estimates for the prevention options above.

Learn more about how to protect yourself and get information tailored to meet your needs from CDC’s HIV Risk Reduction Tool (BETA).

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