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The only way to find out whether you have HIV is to have a blood test.

You can't tell if someone has HIV by looking at them. Some people don't get any symptoms for 10 years after becoming infected with HIV. For those 10 years, they look and feel well.¹

It's important to get a blood test if you think you may have been infected. There are several different kinds of blood test.

To learn more see, Blood tests for HIV.

Most people worry a lot about having an HIV test. It's a big decision. But if you're worried that you might have been in contact with the virus then there are a few reasons why you should have a test sooner rather than later.²

• If you have a positive result you will also get information about the damage HIV has caused to your immune system and to help you decide when to start treatment.
• You'll be able to take care to avoid spreading the virus to other people. (See What should I do if I get a positive result?)
• If you're pregnant, or planning to become pregnant, there are treatments that can reduce the chances of your baby getting the virus. See Passing HIV from mother to baby.

If you get a positive HIV blood test, it means that you have been infected with HIV. And it means you can pass it on to other people. It doesn't mean that you have AIDS.

Once you're infected with HIV, the virus starts to attack your immune system, the cells that protect you from infections. But it takes many years for this damage to affect your health. And there are drugs that can help you stay healthy for longer.

Your doctor will usually do two more blood tests to see whether HIV has damaged your immune system. These tests are called a viral load test and a CD4 count test.

To find out more about these measures, see:

• Viral load
• CD4 count.

Getting a positive test result can be a huge shock. And you'll probably have lots of questions. There are many people and organizations you can turn to for advice. To learn more, see What should I do if I get a positive result?

This information is for educational use only, and is not a substitute for prompt professional medical advice. Readers should always consult a physician or other professional for advice and treatment. ©BMJ Publishing Group Limited 2008. All rights reserved.