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What does undetectable mean?

“Undetectable” means that the amount of HIV found in your blood is so low - fewer than 50 copies of HIV per milliliter of blood - that’s considered undetectable. More importantly, if someone is "undetectable" for six or more continuous months while on treatment, it means they can’t transmit HIV.

What is viral load?

It is the amount of HIV virus in your body. When a person takes their HIV medication as prescribed, the amount of HIV virus in the body goes down. An undetectable viral load has different measures depending on the test and country. For instance, in the U.S., it is defined as having fewer than 50 copies of HIV per milliliter of blood. Studies show that HIV transmission does not occur if viral load is <200 copies/ml. This is also called being “virally suppressed.” Being “undetectable” and “virally suppressed” are often used interchangeably. They both indicate that HIV transmission will not occur.

So, someone that is undetectable can’t transmit HIV sexually?
That’s correct! An HIV-positive person that is undetectable or virally suppressed, and taking their medications regularly, cannot transmit HIV to another person. There have been no confirmed cases of HIV sexual transmission from a person with an undetectable viral load. Three international studies showed no HIV transmissions among mixed-status couples when the partner with HIV was undetectable for six months or longer. This included more than 75,000 acts of reported condomless sex among mixed-status heterosexual and gay male couples.
You can read the studies for yourself here: HPTN 052, PARTNER and Opposites Attract.

After I begin HIV treatment, how long does it take for the risk of sexually transmitting HIV to become effectively zero?

There is effectively no risk of sexual transmission of HIV when the partner living with HIV has achieved an undetectable viral load and then maintained it for at least six months. Most people living with HIV who start taking antiretroviral therapy daily as prescribed achieve an undetectable viral load within one to six months after beginning treatment.

If I’m undetectable and I stop taking my medication will I stay undetectable?

If you stop taking your medication, your viral load will increase and you will not stay undetectable. In 2006, NIAID’s large clinical trial called SMART showed that people receiving intermittent antiretroviral treatment had twice the rate of disease progression compared to those receiving continuous treatment. It’s important to take your medication every day to maintain your undetectable status. The only way to stay undetectable is to take your medication every day.

Can I get other STIs if I am undetectable?

Yes, HIV medications do not prevent other sexually transmitted infections.  STIs may also cause viral load to increase.

Do I need to use condoms if I am untransmittable?

It’s up to you. Condoms provide protection for other STIs.