The Human Immunodeficiency Virus (HIV) does not spread easily. In the U.S., HIV is mainly spread by having sex or sharing syringes and other injection equipment with someone who has HIV.

You can’t get HIV from mosquito bites, coughing or sneezing, sharing household items, or swimming in the same pool as someone with HIV. You also can’t get HIV from a sex partner who has HIV, is on antiretroviral treatment (ART), and has an undetectable viral load.

No documented cases of HIV have been caused by sweat, saliva, or tears. In extremely rare cases, small amounts of blood in your mouth might transmit HIV during open mouth kissing or oral sex. Blood can come from flossing your teeth, or from sores caused by gum disease, or by eating very hot or sharp, pointed food.

To infect someone, the virus has to be at a detectable level in the body of the person with HIV. It then has to get past the body’s defenses. These include skin and saliva. If your skin is not broken or cut, it protects you against infection from blood or sexual fluids. Saliva can help kill HIV in your mouth. If HIV-infected blood or sexual fluid gets inside your body, you may become HIV positive. This can happen through an open sore or wound, during sexual activity, or if you share equipment to inject drugs.

HIV can also be spread from a birthing person to their child during pregnancy, childbirth, or breastfeeding. This is called perinatal transmission.


Unless you are 100% sure that you and the people you have sex or share needles with do not have HIV, you should take steps to prevent getting HIV. People who have recently acquired HIV (within the past 2-3 months) are most likely to transmit HIV to others. This is when their viral load is the highest. In general, the risk of transmission is higher with higher viral loads and lower with lower viral loads. As mentioned previously, someone with an undetectable viral load cannot transmit HIV to others.

Sexual Activity

You can avoid any risk of HIV if you practice abstinence (not having sex). You also won’t acquire HIV if your penis, mouth, vagina, or rectum doesn’t touch anyone else’s penis, mouth, vagina, or rectum. Safe activities include kissing, massage, masturbation, or hand jobs (mutual masturbation). There are no documented cases of HIV transmission through wet clothing.

Having sex in a monogamous relationship is protective against HIV only if:

    • Both of you do not have HIV
    • The partner with HIV is on ART and has an undetectable viral load
    • You both have sex only with each other
    • Neither one of you gets exposed to HIV through drug use or other activities

Oral sex has a lower risk of infection than anal or vaginal sex, especially if there are no open sores or blood in the mouth.

You can reduce the risk of acquiring HIV and other sexually transmitted infections (STIs) by using barriers like condoms. External condoms go on the penis. Internal condoms go in the vagina or rectum. Some condoms contain chemicals called spermicides which prevent pregnancy but not HIV. They might even increase the risk of HIV transmission if they cause irritation or swelling. When used the right way every time condoms are highly effective in preventing HIV and other STIs. If condoms are paired with other prevention methods such as pre-exposure prophylaxis (PrEP) or ART, they provide even more protection.

When people with HIV are on ART and their viral loads are very low or undetectable, the chance they will transmit HIV is virtually zero. ART does not prevent other STIs. Read more about safer sex guidelines.

Substance Use

Substance use can contribute to the spread of HIV indirectly because alcohol and other drugs can lower people’s inhibitions and make them less likely to use condoms.

Sharing needles, syringes, or other equipment (works) to inject drugs puts people at high risk for getting or transmitting HIV and other infections. People who inject drugs (PWID) account for about 1 in 10 HIV diagnoses in the U.S. Read more about HIV among PWID.

The best way to avoid HIV acquisition is to not use drugs. If you use drugs, you can prevent HIV acquisition by not injecting them. If you do inject, don’t share equipment. If you must share, clean equipment with bleach and water before every use. Syringe services programs (SSPs) can play a role in preventing HIV and other health problems among PWID by providing access to sterile syringes. These programs can also provide comprehensive services such as help with stopping substance use; testing and linkage to treatment for HIV, hepatitis B virus (HBV), and hepatitis C virus (HCV); education on what to do for an overdose; and other prevention services.

Perinatal Transmission

HIV can be transmitted from a birthing person to their baby during pregnancy, childbirth, or breastfeeding. However, it is less common because of advances in HIV prevention and treatment. With no treatment, up to 35% of the babies of birthing people with HIV would be born with HIV. If a person with HIV takes ART daily as prescribed throughout pregnancy and childbirth and gives HIV medicine to the baby for 4-6 weeks after giving birth, the risk of transmitting HIV to the baby is less than 1%.

Keeping an undetectable viral load substantially reduces but does not eliminate the risk of transmitting HIV through breastfeeding. The current recommendation in the U.S. is that people with HIV should not breastfeed their babies. Read more about HIV among pregnant people and among children.

Contact with Blood

HIV is one of many diseases that can be transmitted by blood. Be careful if you are helping someone who is bleeding. If your work exposes you to blood, be sure to protect any cuts or open sores on your skin, as well as your eyes and mouth. Your employer should provide gloves, facemasks, and other personal protective equipment (PPE), plus training about how to avoid diseases that are spread by blood.


If you think you have been exposed to HIV, talk to your healthcare provider, public health department, or employer and get tested.

In addition, discuss whether you should start taking post-exposure prophylaxis (PEP). PEP is the use of antiretroviral medications (ARVs) after a single high-risk event to stop HIV seroconversion. PEP must be started as soon as possible to be effective—and always within 72 hours of a possible exposure.


In addition to PEP, taking PrEP offers significant protection against HIV for people who are vulnerable to getting HIV. PrEP is only available by prescription and only works if taken regularly. Discuss PrEP with your healthcare provider.


HIV does not spread easily from person to person. Blood, sexual fluid, or breast milk containing detectable levels of HIV must get into your body in order to transmit HIV.

To decrease the risk of spreading HIV:

    • Use condoms during sexual activity
    • Do not share drug injection equipment
    • If you have HIV, taking ART will reduce the risk of HIV transmission to virtually zero.
    • If you have HIV and are pregnant, taking ART can reduce the risk of perinatal transmission to 1% or less. Talk with your healthcare provider about this, and about the safest way to feed your baby.
    • Protect cuts, open sores, and your eyes and mouth from contact with blood.

If you are at increased risk for acquiring HIV, talk to your healthcare provider about taking PrEP. If you think you’ve been exposed to HIV, get tested and ask your healthcare provider about taking PEP.



CDC: PEP 101 Consumer Info Sheet

CDC: Find a testing site near you.

National Harm Reduction Coalition: Getting Off Right: A Safety Manual for Injection Drug Users

Psychonaut Wiki: Safer Injection Guide

North America Syringe Exchange Network (NASEN): Find a syringe service program (SSP) near you

Reviewed March 2021

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