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Treatment as Prevention

Undetectable=Untransmittable (U=U)

People who are living with HIV should take medicine to treat HIV as soon as possible. HIV medicine is called anti-retroviral therapy, or ART. If taken as directed, HIV medicine reduces the amount of HIV in the body (viral load) to a very low level, which keeps the immune system working and prevents illness. This is called viral suppression—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 cannot detect it (called an undetectable viral load). If you are virally suppressed or have an undetectable viral load, your HIV is under control.

Getting and keeping your HIV under control is the best thing people living with HIV can do to stay healthy. Another benefit of reducing the amount of virus in the body is that it helps prevent transmission to others through sex or needle sharing, and from mother to child during pregnancy, birth, and breastfeeding. This is sometimes referred to as "treatment as prevention." There is strong evidence about treatment as prevention for some of the ways HIV can be transmitted, whereas more research is needed for other ways.

Viral Suppression

Sexual Transmission

People living with HIV who take HIV medicine as prescribed and get and keep an undetectable viral load have effectively no risk of transmitting HIV to their HIV-negative sexual partners.

Transmission from Sharing Needles or Other Injection Drug Use Equipment

We don't know whether getting and keeping HIV under control prevents HIV transmission through sharing needles or other injection drug equipment. While we do not yet know if or how much being undetectable or virally suppressed prevents some ways that HIV is transmitted, it is reasonable to assume that it provides some risk reduction.

Transmission from Pregnancy, Labor, and Delivery

If a woman living with HIV can take HIV medicine as prescribed throughout pregnancy, labor, and delivery and if HIV medicine is given to her baby for 4-6 weeks after delivery, the risk of transmission from pregnancy, labor, and delivery can be reduced to 1% or less.

Transmission from Breastfeeding

IHS follows the CDC recommendation that mothers who have questions about breastfeeding or who want to breastfed should receive patient-centered, evidence-based counseling on infant feeding options, allowing for shared decision-making. Counseling should begin before conception, or as early as possible in pregnancy and should be reviewed throughout the pregnancy and again after delivery. During counseling, healthcare providers can share information about ways to reduce the risk of HIV transmission through breast milk:

  • For mothers on antiretroviral therapy (ART) with a sustained undetectable HIV viral load during pregnancy, the risk of transmission through breastfeeding is less than 1%, but not zero.
  • Replacement feeding with properly prepared formula or pasteurized donor human milk from a milk bank eliminates the risk of postnatal HIV transmission to the infant.

Mothers with HIV who choose to breastfeed should receive close follow-up and be supported in minimizing the risk of HIV transmission to their infants. Healthcare providers are encouraged to consult the National Perinatal HIV/AIDS Hotline (1-888-448-8765) if they have questions regarding mothers with HIV who want to breastfeed.

The CDC offers the following information:


HIV/AIDS Management Consultation Service for Clinicians
9 a.m. – 8 p.m. ET, Monday – Friday
For more information, visit the National Clinicians Consultation Center Exit Disclaimer: You Are Leaving .