Undetectable = Untransmittable (U=U)

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When taken as prescribed, HIV medications can decrease the amount of HIV present in a person's blood, or "HIV viral load", to be too low to measure. This is called being undetectable. Being undetectable prevents HIV disease from progressing and allows people to live long and healthy lives. It also protects the health of their sex partners.

People cannot pass HIV through sex when they have undetectable levels of HIV. This prevention method is estimated to be 100% effective as long as the person living with HIV takes their medication as prescribed and gets and stays undetectable. This concept known as Undetectable = Untransmittable (U=U).

How it works

1. Become undetectable. This can take up to 6 months after starting HIV medication. Your health care provider will perform blood tests and let you know when you're undetectable.
2. Stay undetectable. Get a second undetectable test result at least 6 months after the first. Continue to take your HIV medications daily and visit your health care provider regularly. They will monitor your blood tests to make sure you’re still undetectable.

For more information

• Effectiveness of Prevention Strategies to Reduce the Risk of Acquiring or Transmitting HIV
  Information from the Centers for Disease Control and Prevention (CDC) about the effectiveness of different HIV prevention methods and the evidence supporting them.
  
  
• 10 Thing to Know About HIV Suppression
  Visit the National Institute of Allergy and Infectious Diseases to learn more about HIV suppression, or being undetectable, and see a video of how it works.
  
  
• HIV Treatment as Prevention
  U=U only applies to sexual transmission of HIV. See HIV Treatment as Prevention to learn how HIV treatment impacts perinatal (mother-to-child) and injection drug use transmission.
  
  
• HIV Undetectable = Untransmittable (U = U)
  The New York City Health Department page about U=U includes frequently asked questions.
  
  
• HIV Undetectable = Untransmittable (U = U) — Information for Providers
  The New York City Health Department page about U=U information for health care providers.
  
  
• Prevention Access Campaign
  The Prevention Access Campaign started the international U=U campaign. View the consensus statement, frequently asked questions, list of community partners and more.
  
  
• Positive Series
  Free, customizable U=U educational materials based on real people’s stories that have been translated into several languages.