UPDATE COMING We’re currently working to update this article. Studies have shown that a person living with HIV who is on regular antiretroviral therapy that reduces the virus to undetectable levels in the blood is NOT able to transmit HIV to a partner during sex. This page will be updated soon to reflect the medical consensus that “Undetectable = Untransmittable.”

When someone contracts the human immunodeficiency virus (HIV) timing can affect HIV test results. Tests have become more accurate, but none of them can detect an HIV infection immediately after it’s contracted.

Your body’s defense mechanisms kick into action after contracting HIV. Your immune system begins to develop antibodies to attack the virus. This process is called seroconversion. During the initial seroconversion stage, there may not be detectable levels of HIV antibodies in your blood.

During seroconversion an HIV blood test could produce a false negative result. You won’t get a positive HIV test until your body makes enough HIV antibodies to be detected.

How long does seroconversion take?

The timeframe between when you contract HIV and when tests can detect the infection is known as the seroconversion window. Everyone’s immune system is different. This makes it difficult to predict how long this stage will last.

Scientists have developed sensitive blood tests since the early days of the HIV epidemic. It’s now possible to detect HIV antibodies earlier than ever before. According to Johns Hopkins Bloomberg School of Public Health, most people test positive within a few weeks of contracting HIV. For others, it may take up to 12 weeks.

Will you experience symptoms during seroconversion?

During the seroconversion window, you might develop symptoms similar to the flu or other common viruses that include:

  • swollen lymph nodes
  • headache
  • rash
  • fever

Your symptoms may last from a few days to a few weeks. And they may range from mild to severe. But it’s possible to pass through the seroconversion stage without experiencing any symptoms at all. During this time, you might not even realize that you’ve contracted an infection.

Can you transmit HIV during the seroconversion window?

It’s important to know that you can transmit HIV during the seroconversion window.

The time between exposure and your immune system’s initial response is a period of “acute HIV infection.” Following the initial infection, the amount of HIV in your body is extremely high. So is your risk of transmitting the virus. That’s because your body has yet to manufacture the antibodies needed to fight it, and you’re not yet receiving treatment.

During this stage, most people have no idea that they’ve contracted HIV. Even if you’ve been tested, you may have received a false negative result. This might lead you to engage in risky practices, such as unprotected sex, and unknowingly spread the virus to other people.

What should you do if you think you’ve been exposed to HIV?

If you think you might have been exposed to HIV, get tested. If your initial test results are negative, schedule a follow-up test.

Ask your doctor where you can get tested and when you should schedule a follow-up test. The actions you take now can help stop the spread of the virus. Until you’re confident that you’re HIV-free, avoid sexual contact or use a condom during sex. It’s also important to avoid sharing needles with others.

To find an HIV testing site near you, visit GetTested.cdc.gov.

What does the HIV test involve?

Your doctor will collect a sample of your blood to test for HIV. A trained medical professional can collect the sample at your doctor’s office, blood bank, or other site. They will draw your blood from a vein on the inside of your arm.

They will start by cleaning the injection site. Then they will wrap an elastic band around your arm to cause your vein to swell. They will inject a needle into the vein and draw a sample of your blood into a vial.

Once they’ve collected a sample of your blood, they will send it to a laboratory for testing. If HIV antibodies are not detected, your test results will be negative. If HIV antibodies are detected, your results will be positive.

Home test kits are also available, but they’re less reliable than professional tests. You should always have a professionally administered test to confirm if you’ve contracted HIV.

What happens if you test positive for HIV?

If you test positive for HIV, ask your doctor about treatment options. You don’t need to wait until you feel ill to begin treatment. Earlier diagnosis and treatment, and more effective treatment options are helping people who are HIV-positive live longer and healthier lives than ever before.

Your doctor will prescribe medications to treat your condition. They can also provide information about safe sex practices. It’s important to notify anyone that you’ve had sexual contact with who might have contracted or passed HIV to you, so they can be tested too. It’s also important to practice safe sex to avoid passing the virus onto others.


If you suspect you’ve been exposed to HIV, don’t wait to act. Make an appointment with your doctor, tell them when you might have been exposed, and get an HIV blood test.

Keep in mind, timing matters. No test can detect an HIV infection immediately after you contract it. It may take up to 12 weeks for HIV antibodies to become detectable in your blood.

If you receive a negative result on your first test, ask your doctor if and when you should schedule a follow-up test.

And remember, you can still pass the virus on to others, even before it becomes detectable, and even after you are started on anti-viral medications. Take steps to protect others by practicing safe sex and never sharing needles.