Viral Suppression and an Undetectable Viral Load

Content From: HIV.govUpdated: June 27, 20244 min read


U equals U

Viral Suppression and Undetectable Viral Load: What Do They Mean?

If taken as prescribed, HIV medicine reduces the amount of HIV in your blood (also called your viral load) to a very low level. This is called viral suppression. Viral suppression is defined as having less than 200 copies of HIV per milliliter of blood. Viral suppression helps to keep you healthy and prevents transmission.

HIV medicine can make your viral load so low that a standard lab test can’t detect it. This is called having an undetectable viral load.

Getting and keeping an undetectable viral load is the best thing people with HIV can do to stay healthy. Treatment with HIV medicine is recommended for all people with HIV, regardless of how long they’ve had the virus or how healthy they are.

How Do You Get Your Viral Load to Undetectable and Keep It There?

People with HIV can get and keep an undetectable viral load by taking HIV medicine (called antiretroviral therapy or ART) exactly as prescribed. It’s important to start HIV treatment as soon as possible after diagnosis. Almost everyone who takes HIV medicine as prescribed can reach an undetectable viral load, usually within six months after starting treatment.

However, ART does not cure HIV. HIV is still in your body when your viral load is suppressed, even when it is undetectable. You need to keep taking your HIV medicine as prescribed. If you skip doses, even now and then, your viral load will quickly go back up, causing your immune cells to drop.

If you have stopped taking your HIV medicine or are having trouble with taking your doses as prescribed, talk to your health care provider as soon as possible about strategies to get your viral load suppressed.

Get tips on taking HIV medicine as prescribed.

If the HIV medicines you are taking don’t suppress your viral load, you and your health care provider can talk about whether another combination of HIV medicines might work better for you. There are many different treatment options available.

Benefits of Having an Undetectable Viral Load


There are important health benefits to having a suppressed or undetectable viral load. People with HIV who know their status, take HIV medicine as prescribed, and get and keep an undetectable viral load can live long and healthy lives.

There is also a major prevention benefit. People with HIV who take HIV medicine as prescribed and get and keep an undetectable viral load will not transmit HIV to their HIV-negative partners through sex. This is sometimes called treatment as prevention or undetectable = untransmittable (U=U).

In addition to preventing sexual transmission of HIV, studies have shown that there are other prevention benefits of taking HIV medicine to get and keep an undetectable viral load:

  • It reduces the risk of HIV transmission to the child during pregnancy, labor, and delivery. If a pregnant person takes HIV medicine daily as prescribed throughout pregnancy, labor, and delivery and gives HIV medicine to the baby for up to 6 weeks after delivery, the risk of HIV transmission to the baby can be 1% or less. See our page on Preventing Perinatal Transmission of HIV for more information.
  • It substantially decreases the risk of transmitting HIV to your baby through breastfeeding to less than 1%. However, the risk is not zero. If you are pregnant or thinking of becoming pregnant, talk to your health care provider about what infant feeding choice is right for you. See our page on Preventing Perinatal Transmission of HIV for more information. 
  • It may reduce HIV transmission risk for people who inject drugs. Scientists do not have enough data to know whether having a suppressed or undetectable viral load prevents HIV transmission through sharing needles, syringes, or other injection drug equipment (for example, cookers). It very likely reduces risk, but it’s unknown by how much. Even if you are taking HIV medicine and have an undetectable viral load, use new equipment each time you inject and do not share needles and syringes with other people.

Read about the scientific evidence of an undetectable viral load in preventing the sexual transmission of HIV.

Talk with Your Health Care Provider

Talk with your health care provider about these benefits of HIV treatment and discuss which HIV medicine is right for you. Stay in medical care and discuss how frequently you should get your viral load tested to make sure you get and keep an undetectable viral load.

If your lab results show that the virus is detectable or if you are having trouble taking every dose of your medicine, you can still protect your HIV-negative partner by using other methods of preventing sexual transmission of HIV such as pre-exposure prophylaxis (PrEP) for an HIV-negative partner until your viral load is undetectable again. PrEP is medicine that people at risk for HIV take to prevent getting HIV from sex or injection drug use. Also talk to your partner about post-exposure prophylaxis (PEP) if you think they may have had a possible exposure to HIV (for example, if a condom breaks during sex and you don’t have an undetectable viral load).

Also talk to your provider about ways to prevent other sexually transmitted infections (STls), such as gonorrhea, chlamydia, or syphilis. Having an undetectable viral load only prevents transmission of HIV, not other STls.