HIV (human immunodeficiency virus) is a virus that attacks the immune system and weakens your ability to fight infections and disease.
AIDS is the final stage of HIV infection, when your body can no longer fight life-threatening infections.
There's no cure for HIV, but there are treatments to enable most people with the virus to live a long and healthy life. With early diagnosis and effective treatment, most people with HIV won't go on to develop AIDS.
This topic covers:
Symptoms of HIV infection
Most people experience a short, flu-like illness two to six weeks after HIV infection, which lasts for a week or two.
After these symptoms disappear, HIV often won't cause any symptoms for many years, although the virus continues to damage your immune system. This means many people with HIV don't know they're infected.
Anyone who thinks they could have HIV should get tested. Certain groups of people are advised to have regular tests as they're at particularly high risk, including:
- gay and bisexual men
- Black African heterosexuals
- people who share needles, syringes or other injecting equipment
Read about symptoms of HIV.
Causes of HIV infection
HIV is found in the body fluids of an infected person. This includes semen, vaginal and anal fluids, blood and breast milk.
It's a fragile virus and doesn't survive outside the body for long. HIV can't be transmitted through sweat or urine.
The most common way of getting HIV in the UK is by anal or vaginal sex without a condom. Other ways of getting HIV include:
- using a contaminated needle, syringe or other injecting equipment
- transmission from mother to baby during pregnancy, birth or breastfeeding
It's also possible for HIV to spread through oral sex and sharing sex toys, although the chances of this happening are very low. For example, it's estimated that you only have a 1 in 5,000 chance of getting HIV if you give unprotected oral sex to someone with the infection.
Read about what causes HIV.
Seek medical advice as soon as possible if you think you might have been exposed to HIV. You can get tested in a number of places, including your GP surgery, sexual health clinics and clinics run by charities.
Find HIV testing services near you
The only way to find out if you have HIV is to have an HIV test. This involves testing a sample of your blood or saliva for signs of the infection.
It's important to be aware that:
- emergency anti-HIV medication called PEP (post-exposure prophylaxis) may stop you becoming infected if started within three days of possible exposure to the virus, and starting it as soon as possible is recommended
- an early diagnosis means you can start treatment sooner, which can improve your chances of controlling the condition
- HIV tests may need to be repeated one to three months after potential exposure to HIV infection (this is known as the "window period"), but you shouldn't wait this long to seek help
- clinic tests can sometimes give you a result in minutes, although it may take a few days to get the result of a more detailed blood test
- home-testing or home-sampling kits are available to buy or order online or from pharmacies – depending on the type of test you use, your result will be available in a few minutes or a few days
If your first test suggests you have HIV, a further blood test will need to be carried out to confirm the result. If this is positive, you'll be referred to a specialist HIV clinic for some more tests and a discussion about your treatment options.
Read about diagnosing HIV.
Treatment for HIV
Antiretroviral medications are used to treat HIV. They work by stopping the virus replicating in the body, allowing the immune system to repair itself and preventing further damage. These come in the form of tablets, which need to be taken every day.
HIV is able to develop resistance to a single HIV drug very easily, but taking a combination of different drugs makes this much less likely. Most people with HIV take a combination of three antiretrovirals and it's vital that the medications are taken every day as recommended by your doctor.
Read about treating HIV.
Living with HIV
If you're living with HIV, taking effective antiretroviral therapy (where the HIV virus is "undetectable" in blood tests) significantly reduces your risk of passing on HIV to sexual partners. It's rare for a pregnant woman living with HIV to transmit it to her babies, provided she receives timely and effective antiretroviral therapy and medical care.
You'll also be encouraged to:
- take regular exercise
- eat a healthy diet
- stop smoking
- have yearly flu jabs to minimise the risk of getting serious illnesses
Without treatment, the immune system will become severely damaged and life-threatening illnesses such as cancer and severe infections can occur. This is known as late-stage HIV infection or AIDS.
Read about living with HIV.
Anyone who has sex without a condom or shares needles is at risk of HIV infection.
The best way to prevent HIV is to use a condom for sex and to never share needles or other injecting equipment (including syringes, spoons and swabs). Knowing your HIV status and that of your partner is also important.
For people with HIV, effective antiretroviral therapy significantly reduces the risk of passing HIV to sexual partners.
Read about preventing HIV.
Page last reviewed: 02/08/2016
Next review due: 02/08/2019