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How do HIV tests work and what's involved?

Blood sample being given for HIV test

• There are plenty of places which offer free HIV testing - a quick search on the internet will help you find your nearest service provider.    

• Testing for HIV is a really simple process and usually involves taking a small sample of blood or oral fluid. 

•  Some HIV tests will give a result within 20 minutes and other tests are sent to a lab so it may take a few weeks to get your results.

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.

Where can I get an HIV test? 

Depending on where you are in the world, there are a number of places that you can get tested for HIV. The best first step is to search online for "HIV testing”, plus your location. This will generally give you a good idea of where to go, or at least give you a starting point.

If you have limited internet access, it’s always worth asking local sexual health charities or health authorities to see what you have in your area – they should also be able to direct you to somewhere which offers testing for 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.

How accurate are different types of HIV tests?

Modern HIV tests are extremely accurate. There are a variety of different HIV tests and your 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.

How long an HIV test takes to give you an accurate result depends on the type of test you are taking. 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 which may take between a few days to a few weeks for you to receive a final result.

How do different 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 three months after exposure, because this is how long it takes your body to produce enough antibodies for it to show up in a test. It usually a few days to a few weeks to get results back for this type of 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 reliably detect HIV from one month after you have been infected. It usually takes a few days to a few weeks to get results back for this type of test.

Rapid HIV tests

There’s now a variety of different rapid tests. Most test for HIV antibodies by taking a prick of blood from your finger. These tests are only accurate three months after exposure. Rapid tests give results in just 20 minutes, so results can now be given on the spot at many healthcare centres. 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).


HIV self-testing is only available in a handful of countries but offers the convenience of taking a test in the comfort of your own home.

If you do order a self-testing kit, it’s best to check that the kit has been approved with a ‘CE’ (Europe) or FDA (USA) mark on it. That way, you’ll know that the tests are regulated and work properly. After following the instructions that come with your kit, you should get a result in 15 – 20 minutes.

If you do test positive for HIV, you should follow up with a healthcare professional to get your result confirmed. They will also ensure that you get the necessary follow-up care with treatment and support with counselling. 

Read on to find out: What happens after an HIV test and getting the results?

Photo credit: ©AVERT by Corrie Wingate

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Last full review: 
22 September 2017
Next full review: 
22 September 2020

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Last updated:
24 January 2018
Last full review:
22 September 2017
Next full review:
22 September 2020