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What's involved in HIV tests?

What's involved

Blood sample being given for HIV test

•    Testing usually involves taking a small sample of blood or oral fluid. 

•    Rapid tests will give a result within 20 minutes. Other tests are sent to a lab so it may take up to two weeks to get your results.

•    If you visit a health professional within 72 hours of suspected infection, you may be offered PEP (post-exposure prophylaxis) to prevent infection. You’ll be asked to come in for testing at a later date. 

It is really common to feel a little worried about going for an HIV test. But making the decision to test is the best thing you can do for your health. The process is quick, painless, confidential and almost always free.

The healthcare worker – there to help you!

Before you test, your healthcare worker will talk to you about your sexual health, why you’ve decided to test, and any risks you may have taken.

Remember, the healthcare professional is not there to judge you. There is most likely nothing you can say that they haven’t heard from someone else. Be honest with them, and ask as many questions as you want – that is what they are there for.

You should never feel pressured to test. The results will be completely confidential and you should only go through with it if you want to.

If the doctors feel you are at a high risk of HIV, they may give you post-exposure prophylaxis (PEP). This is a course of emergency HIV treatment that will reduce your chance of being infected with HIV. Speak to your healthcare worker for more information about this.  

The HIV test

There are a variety of different HIV tests. The healthcare worker should explain which test you will be given and how you will get your result. Normally, testing involves taking a small sample of blood from either your finger or your arm, or a sample of oral fluid. If you are taking a rapid test, you will be given your results within 20 minutes. Other types of tests will be sent to a laboratory and you may have to wait for the result. It can take between a day and two weeks for the final result.

How HIV tests work

Third generation HIV tests (ELISA antibody)

When you become infected with HIV, your body will start to produce specific antibodies (proteins that attach to the virus to try and destroy it). An HIV antibody test looks for these antibodies in your blood, saliva or urine. If these antibodies are found, it means you are infected with HIV. This test is only accurate after three months, because this is how long it takes your body to produce enough antibodies for it to show up in a test.

Fourth generation HIV tests (ELISA combined antigen/antibody)

Fourth generation tests look for HIV antibodies, but also for something called p24 antigens. The p24 antigens are part of HIV itself, so you have a lot of these in your blood in the first few weeks after infection. This is why you are most infectious to others in this period too. Fourth generation tests can detect HIV from 11 days to 1 month after you have been infected.

Rapid HIV tests

Results for your HIV test can now be given at the healthcare centre, without the need for samples to be sent to a laboratory. There is a variety of different rapid tests and most test for HIV antibodies. While these tests are reliable, laboratory testing may be better in some situations, as rapid tests have a slightly higher chance of giving a 'false positive' result (shows you have HIV when you don't).

Here is a breakdown of the most common tests:

HIV test

What do they test for?

What is the window period?

How long for the results?


Third generation antibody tests

HIV antibodies

3 months

 Between 1 to 7 days


Fourth generation antibody/antigen tests

HIV antibodies and p24 viral proteins (antigens)

11 days – 1 month

Between a few days and a few weeks


Rapid tests

HIV antibodies

3 months

Within 20 minutes

Satisfactory for uncomplicated infection


HIV self-testing is only available in the USA, France and the UK. These rapid tests give a result in 15 – 20 minutes.

If you decide to test for HIV in your home, make sure that the testing kit you are using is made specifically for self-testing and that it has a ‘CE’ mark on it (UK), or it is FDA-approved (USA). That way, you’ll know that the tests are regulated and work properly. It is also very important that you follow the instructions on your HIV testing kit. If you have any questions about self-testing, speak to a healthcare professional.

Read on to find out: Where to get tested?

What's involved flow graphic

What is involved

Photo credit: ©AVERT by Corrie Wingate

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Last full review: 
20 January 2016
Next full review: 
20 January 2019

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Last updated:
15 June 2017
Last full review:
20 January 2016
Next full review:
20 January 2019