What Is the HIV Window Period?

It takes time after the human immunodeficiency virus (HIV) enters your body before a test can detect it, and this period of time is known as the HIV window period. If you take a test during your window period, the HIV test may show up as negative even if you have been infected with HIV. You can still pass the virus on to someone else during this time. It's important to consider this window so you can get accurate test results and take precautions to protect yourself and others.

What Is the HIV Window Period?

The time between when a person gets HIV and when a test can accurately detect it is called the window period.

During the window period, a person infected with HIV can still pass the virus on to others, even though the virus isn't detected.

The window period varies with different types of HIV tests.

• In general, antibody tests that use blood from a vein will detect HIV sooner than tests done with blood from a finger prick or with oral fluid.
• Currently, no HIV tests can detect HIV immediately after exposure to the virus.

When Should I Have an HIV Test?

Testing is highly recommended for anyone who feels like they have been exposed to the virus or is at high risk of being infected. High-risk activities include non-monogamous sex, unprotected sex, and injectable drug use.

If you know the moment you may have come into contact with HIV, get a test three months later after that date. Getting tested three months after exposure gives a 99% accurate test result.

Testing for HIV is available at a hospital, clinic, pharmacy, community clinic, family planning clinic, youth center, mobile sites, or with a take-home test. To find a testing site near you, use the online locator offered by the U.S. Department of Health and Human Services. Many of the sites offer walk-in testing. Some require an appointment.

Accuracy for Types of Tests 

The window period for each type of HIV test is as follows:

• Nucleic acid test (NAT): A NAT can tell if you have HIV infection 10 to 33 days after exposure.
• Antigen/antibody test: An antigen/antibody test can usually detect HIV infection 18 to 45 days after exposure. Antigen/antibody tests done with blood from a finger prick take longer to detect HIV, usually 18 to 90 days after an exposure.
• Antibody test: An antibody test can take 23 to 90 days to detect HIV infection after an exposure.

Precautions During the Window Period

It's important to remember that a person can still pass HIV on to someone else through sex or sharing needles during the window period. Anyone who suspects that they have been exposed to HIV should take precautions and avoid spreading the virus starting right at exposure.

Post-Exposure Prophylaxis (PEP)

Post-exposure prophylaxis (PEP) is given to someone if they think they have been exposed to HIV within the past 72 hours. It is a short-course treatment that prevents the virus from taking hold in your body. However, it has to be started within 72 hours of exposure, or it would not work. The duration of PEP treatment is 28 days.

You may be prescribed PEP if you:

• Think you may have been exposed to HIV during sex (for example, if you had a condom break)
• Shared needles
• Were sexually assaulted
• Were potentially exposed to HIV through a needlestick injury

While PEP is not 100% effective, it is very effective at preventing an HIV infection if a person begins to take it right after exposure. It may cause minor side effects, or interact with other drugs a person is taking. Be sure to discuss all the potential risks of taking PEP with a doctor. While taking PEP, it’s still important to keep using other HIV prevention methods.

Preventing the Spread of HIV

People who suspect they have been exposed to HIV should still exercise caution to avoid HIV transmission during the window period.

They can do so in several ways:

• Use a condom during sex
• Reduce your number of sexual partners
• Consider using pre-exposure prophylaxis (PrEP), a type of medication that reduces your partners' chances of getting HIV
• Get tested for other STDs and ask your partners to do the same
• Don't share drug needles with others

A Word From Verywell 

Waiting for HIV test results during the window period can be frustrating because you want to know for sure whether you have been exposed. It is, however, important to be patient because waiting till after the window period to get tested will give you the most accurate results. Even if you get a negative result during the window period, you will have to get tested again after the window period is over to confirm the result. During this time, it's still important to take all necessary precautions to avoid spreading the virus.