HIV (human immunodeficiency virus) is a virus that damages your immune system.

Once someone acquires HIV, it remains in their body for the rest of their life. People diagnosed with HIV are said to be living with HIV.

There’s currently no cure for HIV. However, treatment enables most people with HIV to live a healthy life with a normal life expectancy, especially if they’re diagnosed soon after getting the virus.

After 6 months of successful treatment, a person living with HIV can’t transmit it to sexual partners. This is known as undetectable equals untransmittable’ or ‘U=U’.

HIV can be transmitted in a few ways, all of which can be prevented. This information is mostly about sexual transmission.

Many people living with HIV have no obvious signs and symptoms.

About 2 in 5 people newly diagnosed with HIV in the UK are diagnosed late – this means they’ve been living with undiagnosed HIV for a number of years.

Most, but not all, people who acquire HIV will have some symptoms within a few weeks of getting the virus. This is known as seroconversion illness and can include fever, a rash over the body, sore throat, headache, feeling generally unwell, aches and pains, night sweats, weight loss, tiredness, swollen glands, and illnesses like meningitis. Not everyone has these symptoms and they’re easily mistaken for flu or other common illnesses.

After the first few weeks, most people living with HIV will live for years without any signs or symptoms. If it’s not treated, HIV will eventually damage a person’s immune system until they start to develop serious illnesses or infections.

How will I know if I've acquired HIV?

You can only be certain you’re living with HIV if you have a test. If you or a partner think you might’ve been exposed to HIV, it’s important not to delay seeking advice and getting a test.

Even if you don’t have symptoms, an HIV test is advised every time one of the following applies:

  • you, or a partner, have another sexually transmitted infection
  • you’ve recently had vaginal or anal sex without a condom with a new partner
  • a sexual partner tells you they’re living with HIV
  • you’ve shared needles or injecting equipment
  • you’re pregnant or planning a pregnancy.

Regular testing is advised if you’re sexually active and from a population that’s more affected by HIV (see How common is HIV? in the How HIV’s transmitted section).

If you’re unsure about your HIV status, there are services you can go to for a test, advice and information.

HIV is a virus. If it’s not treated, it can weaken and damage your body’s defence system (the immune system) so that it can’t fight off infections. HIV treatment stops this happening.

If someone’s immune system is damaged by HIV (usually over many years), they may develop one or more serious infections and illnesses, called AIDS-defining illnesses.

Sometimes this is called an AIDS diagnosis. AIDS stands for acquired immune deficiency syndrome, but the term isn’t used very often now. Late-stage or advanced HIV is sometimes used instead.

Almost all people living with HIV who are diagnosed early enough and have effective treatment won’t go on to develop an AIDS-defining illness. It’s also possible to recover from an AIDS diagnosis with treatment.

HIV can be transmitted (passed on) from one person to another through sexual contact, and in a limited number of other ways.

More than 9 out of 10 people who accessed HIV care in the UK in 2019 acquired HIV through sexual transmission.

Most people diagnosed with HIV are on treatment which will make the virus undetectable in their blood. This means they can’t transmit the virus to sexual partners (see the HIV prevention section for more information). HIV is far more likely to be passed on if someone’s unaware they have HIV. This is one reason why regular testing’s so important (see How will I know if I’ve acquired HIV? in the Signs and symptoms section).

HIV can be passed on through blood, semen (cum), pre-ejaculate (pre-cum), vaginal and anal fluids, and breast milk.

It can be passed on through vaginal or anal sex without a condom and without using PrEP (see the HIV prevention section). It can also be passed on by sharing sex toys with another person.

HIV can also be transmitted by sharing needles and other injecting equipment.

If you’re pregnant and living with HIV, it’s possible to transmit the virus to the baby before or during birth, or by breastfeeding. This is extremely rare in the UK as transmission is prevented with HIV treatment.

You can’t acquire HIV from hugging, saliva, kissing, sneezes, coughs, sharing baths or towels, from swimming pools, toilet seats or from sharing cups, plates or cutlery. You can’t acquire HIV from any animals or insects, including mosquitoes.


Can HIV be acquired when receiving healthcare in the UK?

It’s extremely rare to acquire HIV when receiving healthcare in the UK. When caring for any patient, all health professionals in the UK – such as dentists, doctors, midwives and nurses – must follow infection control procedures which will prevent HIV and other blood-borne viruses.

In the UK, organ donors and blood from blood donors are tested to reduce the risk of HIV being transmitted through blood, blood products or donated organs. There have been no new cases of HIV due to blood donation in the UK for more than 18 years.

Some countries don’t have the same standards of medical and dental care as the UK, so there may be a risk of HIV transmission from blood products or un-sterile medical equipment if you receive healthcare in another country.

How common is HIV in the UK?

Anyone can acquire HIV. You don’t need to have lots of sexual partners.

In the UK, fewer than 2 in 1,000 people overall are living with HIV, but people from some groups are affected more than others.

This includes gay and bisexual men and their female sexual partners, Black Africans, people who inject drugs, sex workers, people in prison, trans and non-binary people, and people from countries with high rates of HIV and their sexual partners.

If one of the above applies to you, and you’re sexually active, you may be at higher risk of acquiring HIV than the overall population.

If you have sex without a condom with new partners, or if you or a partner have sex without a condom with other partners, then regular HIV tests can help to keep you and your sexual partner(s) healthy.

How do I prevent HIV transmission during sex?

The following measures can help prevent HIV transmission during vaginal or anal sex.

  • An external condom or internal condom. For anal sex, use water-based or silicone-based lube to reduce the risk of the condom tearing.
  • Treatment as prevention - when you or a partner are living with HIV and on effective treatment (see below, What's treatment as prevention?)
  • Pre-exposure prophylaxis (PrEP) (see below, What is PrEP?).

Condoms or dams (latex or plastic squares) can help protect you from getting or passing on HIV or other STIs during oral sex. 

If you’re at higher risk of acquiring HIV, regular testing can help keep you and your sexual partner(s) healthy.

What’s treatment as prevention?

People who know they’re living with HIV can access treatment to reduce the level of virus in their body. When the level of virus is close to zero, it’s known as having an undetectable viral load or being undetectable.

When a person living with HIV has been on successful treatment for 6 months and has an undetectable viral load, they can’t transmit HIV to sexual partners. This is called ‘treatment as prevention’ (TasP). It’s also known as ‘undetectable equals untransmittable’ or ‘U=U’. In the UK, more than 9 out of 10 people on HIV treatment have an undetectable viral load.

What's PrEP and can I get it to prevent HIV?

PrEP (pre-exposure prophylaxis) is medication taken by someone who’s HIV negative to prevent them acquiring HIV. It’s an effective way to prevent transmission.

It’s available across the UK for people who may be at higher risk of getting HIV.

If you're HIV negative, PrEP may be suitable for you to reduce your risk of getting HIV. A clinician will talk to you to assess this. PrEP is available as a tablet, which you take before and after you have sex and are exposed to HIV.

It doesn’t help protect you from other sexually transmitted infections such as chlamydia, gonorrhoea and syphilis, so you may need to use condoms as well.

Read our PrEP page to find out more.

What's PEP and how soon do I need to use it to prevent HIV?

Post-Exposure Prophylaxis (PEP) involves taking HIV treatment within 3 days (72 hours) of possible exposure to HIV, to prevent infection. It’s a course of HIV treatment taken for 4 weeks. It’s more effective the sooner you take it.

PEP is an emergency treatment. It’s usually only given if you’ve had sex without a condom (and you’re not taking PrEP) in the following situations:

  • anal or vaginal sex with someone who’s HIV positive and not taking treatment, or if the virus is currently detectable in their blood
  • anal sex, where you were the receptive partner, with someone who has a higher chance of having HIV but hasn’t recently been tested.

PEP may also be given in some other situations such as after a sexual assault.

You can get PEP at a sexual health or genitourinary medicine (GUM) clinic or an accident and emergency (A&E) department. A doctor or nurse will ask you some questions to find out if PEP is suitable for you.

What’s an HIV test?

An HIV test checks your blood for HIV antibodies and antigens to see whether the virus is in your body. Antibodies are substances made by your immune system to try and fight the infection. Antigens are a part of the virus.

Anyone can have a test even if you don’t have any signs and symptoms. A test usually involves taking a sample of blood and sending it to a lab to be tested.

It’s also possible to test for HIV using a spot of blood from your finger (made with a pinprick).

Cervical screening (smear) tests, routine blood tests and swabs won’t detect HIV. If you’re not sure whether you’ve been tested for HIV, just ask.

How soon after sex can I have an HIV test?

It’s important not to delay getting a test if you think you might’ve been exposed to HIV. If you think you might’ve been at risk in the last 3 days (72 hours) you may be able to get PEP (see What’s PEP and how soon do I need to use it to prevent HIV? in the HIV prevention section).

If you’ve acquired HIV, it takes time for there to be enough antibodies or antigens in your blood to show up on an HIV test.

This time is sometimes called the ‘window period’. The length of the window period depends on the type of test you take.

  • A blood test done at your local clinic or one you collect at home and send to the lab: These tests have a much shorter window period than other tests – they can give an accurate result 45 days after potential exposure to HIV
  • For tests which give an instant result (for example, home self-test kits using blood from a finger prick or a swab from the mouth), the window period can be between 4 and 12 weeks. The test kit you are using should clearly explain the window period for that test

If you get tested during the window period, your test result may be negative even if you do have HIV. If your test result is negative but you’ve only recently been at risk, you’ll be advised to have a follow-up test to confirm the result.

Where can I get an HIV test?

There are different services you can go to. You can also use a postal testing kit or a self-test (where you read the result yourself). Choose the one you feel most comfortable with.

An HIV test can be done in person at:

  • a sexual health clinic or genitourinary medicine (GUM) clinic
  • an HIV testing centre run by a charity
  • some contraception clinics and young people’s services
  • many GP practices
  • a private clinic (for a fee).

People who inject drugs may be able to get a test through a local drugs service.

Antenatal (pregnancy care) services and some gynaecology services will offer a test.

In some areas, testing is done by trained staff in places such as nightclubs, community events and churches.

If you’re worried that you may've been exposed to HIV, don’t wait to be offered a test. Go to a clinic and ask for a test or get a postal kit or self-test kit.

Postal (self-sampling) tests

Postal tests are available for free in many areas (see free online services). You can also buy them online and from some high-street pharmacies. You take your own blood sample (self-sampling) and post it to a lab to be tested.


You can buy an HIV self-test online (also known as a home testing kit) which can give you your result in around 15 minutes. You take a spot of blood from your finger and test it yourself.

If you choose to buy a kit, check it has a CE mark and is licensed for sale in the UK, such as those at

If you’ve acquired HIV in the last 3 months, a self-test might not be able to detect the virus (see above, How soon after sex can I have an HIV test?). If you think you’ve been exposed to HIV in the last 3 months, ask for a test at a sexual health or GUM clinic.

How soon will I get the test result?

This depends where you had the test. If you were tested in person at a clinic or other service, the doctor, nurse or health adviser will tell you when the result will be available. At most services, the result should be available within 1 week; some may be earlier.

Some clinics and local testing services also offer rapid HIV testing from a spot of blood from your finger. This is when you’re given the result in a short space of time (often within a few minutes).

The rapid test result will be either negative (no HIV antibodies detected) or reactive (HIV antibodies detected). A reactive result is sometimes called a positive result, but it doesn’t necessarily mean you’re HIV positive. If you have a reactive result, another test will be done at a clinic (where they’ll take blood from your arm) to confirm whether or not you’re HIV positive.

If you used a postal kit, it usually takes around a week for the service to contact you with the results. They’ll advise you whether you need to visit a clinic in person for a confirmatory test and for treatment services.

If you used a home self-test, you’ll get the result in around 15 minutes. The test result will be either negative (no HIV antibodies detected) or reactive (HIV antibodies detected). If you have a reactive result, you’ll need to have another test at a clinic (where they’ll take blood from your arm) to confirm whether or not you’re HIV positive.

If you choose a self-test, it’s important to think about how you might feel and what support you may need if your test is reactive.

How accurate are the tests?

No tests are 100% accurate, but HIV tests should pick up almost all instances of HIV if done at the right time. All positive HIV tests are repeated to confirm the result. If your test result is negative, and you haven’t been exposed to HIV in the 3 months before the test, you can be confident you didn’t have HIV at the time of the test.

Will I have to pay for tests and treatment?

HIV testing is available on the NHS free of charge to anyone.

In some areas, postal tests can be ordered free online (see above, Where can I get an HIV test?). You can also choose to buy postal and self-test kits.

Anyone living in England is entitled to free HIV treatment on the NHS. HIV treatment is also available on the NHS in Scotland, Wales and Northern Ireland.

What’s the treatment for HIV?

If HIV is diagnosed, you’ll be referred to a specialist HIV clinic. The clinic will do blood tests to monitor the stage of the infection and you’ll be offered treatment straight away. Treatment is given as a pill or pills which you take every day.

At first, you’ll attend the clinic every few weeks or months but once you’re settled on treatment, you may only need to go twice a year.

At the moment, there’s no cure for HIV. The aim of treatment is to keep the level of HIV in your blood as close to zero as possible, so it can’t harm your immune system. When the level of virus is so low that a test can’t detect it, this is known as an undetectable viral load and is the best result you can get from treatment. This helps keep you healthy and means you can’t transmit the virus to your sexual partner(s).

The earlier that HIV is diagnosed, and treatment started, the more successful it’s likely to be at keeping you healthy.

Your HIV clinic can give you full information about the best treatment options for you, possible side effects and long-term effects of treatment.

HIV support organisations can also provide this information (see Useful links section below).

During pregnancy, treatment can be given to prevent the virus being transmitted to the baby.

What happens when HIV isn’t treated?

It’s important that HIV is treated and monitored by specialist doctors and nurses.

Untreated HIV will cause long-term damage to your health. Eventually, it can develop into late-stage HIV infection, which can lead to death.

This may happen more quickly in some people than others, so if you’ve been at risk of HIV it’s important to get tested so you can begin treatment if you have the virus.

You don’t have to share your HIV status if you don’t want to. It may take some time to adjust to living with HIV.

Staff at your HIV clinic can support you to tell partner(s) when you’re ready, including support with talking to a current or long-term partner about your diagnosis. They’ll also advise you on ways to prevent HIV transmission to your partner(s), including through treatment and condom use.

It’s important that your current sexual partner(s) and any other recent partners are tested. The staff at the clinic can discuss with you which recent partners may need to be tested and help you contact them. This is called partner notification. They’ll be sent a message to say they may have been exposed to a sexually transmitted infection and suggest they go for a check-up. It may or may not say what the infection is. The message won’t have your name on it, so your confidentiality is protected.

Will I know how long I’ve been living with HIV?

An HIV test can’t tell you how long you’ve been living with the virus.

After you’re diagnosed, blood tests will look at the level of damage to your immune system. The results may indicate whether you’ve been living with the virus for a longer or shorter time but can’t confirm this.

If you feel upset or angry about having HIV and find it difficult to talk to a partner, family or friends, don’t be afraid to discuss how you feel with the staff at your clinic or a support organisation.

Does anyone else need to know I’ve had an HIV test?

Information about your HIV test should only be given to someone else with your permission. Talk to the doctor or nurse if you’re concerned about your results being kept confidential.

Can I have children if I’m living with HIV?

Yes. You can take treatment during pregnancy that will stop HIV from being passed on to your baby in pregnancy and birth.

In the UK, fewer than 1 in 100 babies born to people living with HIV during their pregnancy acquire the virus.

It’s possible for someone living with HIV to conceive a child with an HIV negative partner without transmission occurring (for example, because they’re on treatment). Your HIV clinic can give you advice on this.

If you’re living with HIV and could get pregnant, your clinic will support you with your reproductive health choices and with pregnancy and birth if you decide to have children.

What happens if I’m pregnant and find out I’m HIV positive?

You’ll be offered an HIV test as part of the routine screening early in your antenatal care.

If you’re HIV positive, you’ll be referred to a specialist HIV clinic. The staff will help you understand the diagnosis and take immediate steps to prevent the baby acquiring HIV during your pregnancy. They’ll continue to support you through your pregnancy, birth and beyond.

In the UK, you’ll be advised to use formula milk to prevent the low risk of transmitting the virus to the baby through breastfeeding. If you feel strongly that you want to breastfeed, you can discuss this with your clinic. They’ll talk through the benefits and risks with you and can support you to breastfeed, but they’ll need to monitor you and your baby closely.

Aidsmap has more information on having a baby when you’re
living with HIV

    • Use external condoms or internal condoms every time you have vaginal or anal sex. How to use condoms.

    • Standard condoms are suitable for anal sex. Use a water-based or silicone-based lube for anal sex to reduce the risk of the condom tearing.

    • If you have oral sex (going down, giving head), use a condom to cover the penis, or a dam (a latex or soft plastic square) to cover the vulva (external female genitals) or the anus.

    • Avoid sharing sex toys. If you do share them, wash them or cover them with a new condom before anyone else uses them.

    • If you can, avoid using spermicidally lubricated condoms. The spermicide commonly contains a chemical called nonoxinol-9 which may increase the risk of HIV and other infections.

    • If you think you may be at higher risk of HIV, you can consider taking PrEP, a medication that’ll prevent you acquiring HIV. PrEP doesn’t prevent other STIs.

    For more information and support visit:

    HIV testing services

    Order a free postal testing kit:

    Terrence Higgins Trust online test finder

    NHS in person test finder

    Information last updated:
    Next planned review by:

    This website can only give you general information about HIV. Our HIV information is based on evidence-based guidance produced by the British HIV Association (BHIVA), the British Association for Sexual Health and HIV (BASHH) and Public Health England (PHE), with the kind assistance of NAT (National AIDS Trust).

    Contact your doctor, practice nurse or a clinic if you're worried or unsure about anything.