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What is an undetectable HIV viral load?

Medically reviewed by Sally Chao, MD. Last updated on Jan 28, 2022.

Official answer


An undetectable viral load means that the amount of HIV in a person’s blood is no longer detectable on a normal blood test. HIV is a retrovirus, so the treatment is called antiretroviral (ARV) treatment. For most people, ARV drugs will reduce the amount of virus down to an undetectable viral load in 6 months or less.

HIV multiplies in the body by making copies of itself. The number of copies — also called HIV particles — is the viral load.

A person with a detectable viral load can pass HIV to a sexual partner, and a detectable viral load may affect your immune system and result in infections or cancers.

  • Viral load is measured in copies per milliliter of plasma (the clear part of blood without red blood cells).
  • If you have less than 200 copies of HIV per milliliter of plasma, they will not be detectable on a routine HIV viral load blood test.
  • However, you will still test positive for HIV with an at-home or clinic antibody test.

How do ARV drugs cause an undetectable viral load?

There are now more than 30 ARV drugs available to treat HIV. These drugs are approved by the U.S. Food and Drug Administration (FDA). The drugs are divided into eight classes.

Guidelines for treatment recommend starting two ARV drugs from a class of drugs called nucleoside/nucleotide reverse transcriptase inhibitors (NRTIs), along with one ARV drug from another class of ARV drugs. These medications are taken as daily pills. Pregnant and breastfeeding women may also safely take certain ARV drug treatments, which will reduce the risk of passing HIV to a baby.

Although the different types of ARV drugs work somewhat differently, they all prevent HIV viruses from making copies of themselves. This protects the immune system from the damage that would occur if HIV viruses remained at detectable levels in our body over a long period of time. In the past, before today’s ARV drugs, HIV weakened a person’s immune system, resulting in infections or cancers, called opportunistic infections and AIDS-related cancers.

ARV drugs may have side effects, especially when you first start taking them.

  • To reach an undetectable viral load, it is important not to stop ARV therapy if you have side effects.
  • Side effects can be managed with the guidance of a health care provider.
  • In some cases, one or more of your ARV drugs can be changed.

Maintaining an undetectable viral load

Because of ARV drugs, HIV is no longer considered a fatal disease. It is a long-term but manageable disease. However, ARV therapy does not cure HIV. Even when your viral load is undetectable, there is still a small amount of HIV resting inside some cells of your body, called viral reservoirs.

If you skip your daily dose of ARV drugs or you stop because you feel fine, your viral load will go up and you could get sick or spread HIV to a partner. A viral load rebound occurs after stopping or skipping ARV therapy. Not only does this increase your risk of passing HIV to a partner and getting sick, but it can also cause your HIV to become resistant to ARV drugs. Studies show that not taking every pill every day doubles the risk of HIV getting worse.

  • According to the U.S. Department of Health and Human Services (HHS) treatment guidelines, viral load should be measured every 3 to 4 months.
  • If your test shows an undetectable viral load, and a repeat test after at least another 6 months shows a continued undetectable viral load, the viral load is called “durably undetected.”

How safe is sex with an undetectable viral load?

The National Institute of Allergy and Infectious Diseases (NIAID) notes that three major studies showed there is no risk for transmitting HIV sexually between men and women or men and men if one partner does not have HIV and the other has an undetectable viral load. These studies involved more than 3,000 couples having sex without the use of a condom over many years, and there were no cases of HIV transmission.

Therefore, the NIAID says there is no risk of HIV infection if the HIV partner has maintained undetectable viral load for at least 6 months, or durable viral load.

Viral load “blips” are temporary increases in viral load that may occur in people taking ARV therapy every day. Blips are not uncommon and are not a sign of treatment failure.

Some people may decide to continue using condoms even if they or their partner have an undetectable viral load. Another advantage to using a condom is protection against other sexually transmitted diseases that are not affected by ARV therapy. For extra protection, some HIV-negative partners may use pre-exposure prophylaxis (PrEP), which means taking an ARV medication before sex.

If you and your partner decide to have sex without using a condom, make sure your viral load is durably undetected. If your partner also has HIV, you should both have durably undetected viral loads because your partner may have a different strain of HIV that will escape your ARV drugs.

  1. Avert. What Is an Undetectable Viral Load? May 20, 2020. Available at: [Accessed January 5, 2022].
  2. Centers for Disease Control and Prevention (CDC). Undetectable Is Prevention. Available at: [Accessed January 5, 2022].
  3. National Institute of Allergy and Infectious Disease (NIAID). 10 Things to Know About Viral Suppression. June 12, 2020. Available at: [Accessed January 5, 2022].
  4. U.S. Department of Health and Human Services (HHS). HIV Testing. August 16, 2021. Available at: [Accessed January 12, 2022].
  5. Avert. Starting Antiretroviral Treatment for HIV. May 31, 2020. Available at: [Accessed January 5, 2022].
  6. U.S. Department of Health and Human Services (HHS). Guidelines for the Use of Antiretroviral Agents in Adults and Adolescents Living with HIV. June 3, 2021. Available at: [Accessed January 5, 2022].

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