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HIV is a virus that damages the body's immune system so it cannot fight off infections. HIV is most commonly transmitted (passed on) through vaginal or anal sex without using a condom.

Here are some key facts:

  • HIV stands for Human Immunodeficiency Virus 
  • AIDS (Acquired Immune Deficiency Syndrome, sometimes referred to as ‘late stage HIV’) is the final stages of HIV infection when the body can no longer fight off life threatening infections. With early diagnosis and treatment most people with HIV will not go on to develop AIDS
  • In 2013, around 100,000 people in the UK were living with HIV
  • The fact that HIV only affects men who have sex with men is a myth. Over half of those living with HIV are heterosexual
  • HIV can be transmitted through blood, semen (including pre-come) and vaginal fluids (less commonly through oral sex or sex toys)
  • Often you won’t have symptoms for many years but in that time, HIV will multiply and cause progressive damage to your immune system
  • HIV is preventable (through using condoms) and treatable (with drugs called antiretrovirals), but it is not curable
  • HIV can be detected in the body four weeks after exposure to the virus. The most common way of testing for HIV involves taking a small sample of blood 
  • Anti-HIV medication called PEP may stop you becoming infected if taken within 72 hours of exposure but this is only prescribed to those known to be at high risk (see later section 'Treatment of HIV') 

You can read about HIV in more detail below.

Signs and symptoms of HIV

It is thought that around 80% of people with HIV will experience a short, two week illness soon after getting the virus. This illness is known as seroconversion and is a sign that the immune system is reacting to the virus and in doing so, the body produces antibodies (a protein in the blood that fights infection) to HIV. When a HIV test is performed – it is these antibodies that the test is looking for.

This seroconversion illness can be like flu (with sore throat, fever, tiredness, achy joints, swollen glands and a rash) or it could be severe enough to put you in hospital. 

If you experience all of these symptoms at the same time after being in a situation where you think you may have been at risk of HIV, you should have an HIV test.

After this illness, it is often the case that you won’t have symptoms for many years (and some people won’t even experience this seroconversion illness).

But what happens in the meantime is that HIV will multiply and cause progressive damage to your immune system, during which time you can look and feel well.

Once this damage is done, typical symptoms include:

  • Weight loss
  • Persistent diarrhoea
  • Night sweats
  • Infections that keep returning
  • Serious life-threatening illnesses

The earlier that someone with HIV gets a diagnosis, the more likely it is that these problems can be prevented.
So, even if you have had no symptoms, if you have had unprotected sex at any time in the past or if you have shared needles with someone, you should still take a HIV test.

The causes and how it is passed on

HIV lives in the blood and some bodily fluids, so to get HIV, one of these fluids from someone with HIV, has to get into your blood.

The commonest way for HIV to be transmitted from one person to another is through having vaginal or anal sex without a condom. In 2013, 95% of HIV cases were transmitted in this way. The virus exists in blood, semen (including pre-come) and vaginal fluids.

HIV can also be transmitted through: 

  • Sharing sex toys 
  • Sharing needles
  • Oral sex: the risk of this is much lower, but there is a greater risk if someone with HIV ejaculates (comes) in your mouth, and you have ulcerated or bleeding gums.
  • Pregnancy, childbirth or breastfeeding: this is very rare in the UK - and all expectant mothers should be offered an HIV test during their antenatal care. There are steps that can be taken to reduce the possibility of the child contracting HIV, including giving the mother and child antiretroviral HIV drugs, delivering the child by caesarean and not breastfeeding the baby. This can be discussed as part of your antenatal care

Bodily fluids such as urine, sweat or saliva do not contain enough of the HIV virus to infect another person. That means you cannot get HIV from shaking hands, kissing or hugging, using other people's cutlery or cups - or eating food prepared by someone who is HIV positive - sharing towels, toilet seats, or going to swimming pools.

HIV is also not passed on through the air like a cold or flu virus or by bites by mosquitoes.

Who is most at risk?

  • Men who have sex with men are most at risk of getting HIV
  • Women who have sex with men who have sex with men are therefore also exposed to a higher risk
  • People who have had sex without a condom with a person who has lived or travelled in Africa
  • People who inject drugs
  • People who have had unprotected sex with people who inject drugs
  • People who have received a blood transfusion in Africa, eastern Europe, the countries of the former Soviet Union, Asia or central and southern America

Testing for HIV

HIV can be tested for four weeks after exposure to the virus. The test does not detect the virus itself but the antibodies that your body has developed to fight it. The most common way of testing for HIV involves taking a small sample of blood for analysis. In some cases this is sent away to a laboratory and results come back in a few days. Same-day tests are also available and can give an instant result.

It is also possible to test a saliva sample or to test blood taken from pricking the finger with a needle.

If no sign of infection is found, the test results are ‘negative’. If the infection is detected, the test results are ‘positive’. All positive results should be tested again to confirm as sometimes you get what is called a ‘false positive’. This may happen, for example, when antibodies fighting another infection are detected but wrongly identified as being antibodies fighting the HIV infection.

False negatives are also possible and are most likely to happen in the window period between infection and the antibodies reaching a high enough level to be detected (around four weeks).

Whether you have been tested before or not, you should have a test if you think you could be at risk. Delaying testing and treatment will allow the virus to damage your immune system. It also means you could pass the virus to someone else. 

HIV testing is free on the NHS and can be provided at Brook services, GUM or sexual health clinics, clinics run by charities such as the Terrence Higgins Trust and some GP surgeries.

At-home HIV testing

In November 2015, Public Health England launched 'at-home' HIV self-sampling kits which are available free online for people in England at higher risk from HIV, such as men who have sex with men or people from black African communities. 

The kits are discreet and are sent out by first class mail and contain everything you need to take a finger prick blood sample. There will be a prepaid envelope for sending your sample to a laboratory for testing and you will receive your results in around five working days. You can choose how you would like to receive your results and can also track the status of your test. If the results show that it is likely you have HIV you will then be asked to visit a sexual health clinic to confirm the test.

It is also possible to buy other HIV self-testing kits online but it is important that you look for a CE quality assurance mark as poor quality tests are available and may not give you an accurate result.

Treatment of HIV

HIV is preventable and treatable, but it is not curable. If you are diagnosed with HIV, you will need to discuss your treatment carefully with your doctor. 

Generally speaking, if you are found to be HIV positive, you will receive regular blood tests to check how your immune system is coping. If these tests show that the cells in your blood that fight infection have dropped below a certain level, your doctor may recommend that you start treatment.

The aim of treatment is to manage this balance between the levels of HIV in your blood and the infection-fighting cells that your immune system has produced to fight it.

HIV is treated with drugs called antiretrovirals. Antiretrovirals work by stopping the HIV multiplying, which gives the immune system chance to repair itself.  

A combination of antiretrovirals is used because HIV can quickly adapt and become resistant to them. The combination that is most effective will be unique to each person. 

Emergency treatment for HIV
If you think you may have been exposed to HIV within the last 72 hours (three days), it is also possible to take anti-HIV medication called PEP (post-exposure prophylaxis) which may stop you becoming infected. 

Some people describe this as being like the morning after pill (emergency contraception) for HIV. But this is misleading as PEP is a 28-day treatment of powerful drugs and is not guaranteed to work. It is only recommended after high-risk of exposure (for example if a partner is known to be HIV positive). You can read more about PEP on the NHS website.


AIDS is the final stage of HIV infection, when your body can no longer fight life-threatening infections. With early diagnosis and effective treatment, most people with HIV will not go on to develop AIDS.

Page last reviewed: August 2015
Next review due: August 2017

HIV in schools campaign

Watch this short film which was made as part of the 2015 HIV in school campaign by Chiva, a registered charity working across the UK and Ireland to improve care for HIV positive children and their families.