HIV, or Human Immunodeficiency Virus, is a sexually transmitted virus that attacks the specialised cells in the body that constitute the immune system. 

When the immune system is weakened enough, the body is unable to resist the infections which would not usually cause any problem in healthy people (opportunistic infections) and unable to eliminate cancer cells which would not produce a cancer in a healthy person (opportunistic cancers). Such compromised immune system and its consequences are together described as AIDS (Acquired Immune Deficiency Syndrome).

It’s important to note: 

  • You only get HIV from someone who has got HIV.
  • Even if the person has got HIV, if they are on effective treatment, they will not pass the infection to others (U=U, Undetectable = Un-transmissible).
  • Not everybody who has sexual contact with someone who is HIV positive will get HIV even if they are not on treatment.
  • You DO NOT get HIV if the other person has not got HIV.

Management Guidelines


Further Readings

At a glance

They can start with flu-like symptoms and become more serious over time.

See specific symptoms >

The most common cause is unprotected sex.

See specific causes >

PEP can be taken within 72 hours of possible HIV exposure.

Learn more >

Testing & Treatment
Routine test results can be provided on the same day.

Learn more >


What are the symptoms of primary HIV infection?

Most patients will have no symptoms of HIV.

Some may experience flu-like symptoms 2-4 weeks after acquiring HIV infection, and this can last for a few weeks. This is the result of the multiplication of the HIV virus in large amounts – also called ‘seroconversion illness’. This may include:

  • Headache
  • Sore throat
  • Excessive fatigue
  • Chills
  • Fever
  • Muscle pain
  • Swollen lymph nodes
  • Skin rash

However, because these symptoms can be mild and non-specific (i.e. symptoms not exclusive to HIV infection), people often do not seek medical advice until their problem has become serious enough.

Furthermore, the symptoms of primary HIV infection are indistinguishable from other common viral infections (including Covid 19) and can mimic certain STIs, like Secondary Syphilis.

The only way to make an early diagnosis, and thus prevent onward transmissions and prevent complications, is to recognise the potential exposure to the infection and run a HIV test.

What are the symptoms of secondary HIV infection?

During this stage, the HIV infection is still active in the body but reproduces at lower levels. Thus, many patients do not experience any symptoms. For this reason it is sometimes referred to as the asymptomatic phase, or latent infection.

However, other patients experience low grade symptoms over months and years, including:

  • Fever
  • Tiredness
  • Drenching night sweats
  • Poor appetite
  • Weight loss
  • Muscle aches
  • Skin rashes and lumps
  • Diarrhoea
  • Coughing
  • Shortness of breath
  • Headache

It’s common for patients to experience a combination of these symptoms which occur due to the effect of the HIV infection on different body systems.

    What are the symptoms of advanced HIV?

    The result of advanced HIV is AIDS (Acquired Immunodeficiency Syndrome) where the immune system is severely weakened. When this happens, the patient can acquire infections and cancers which are not seen in the general population. We call them ‘Opportunistic infections’ and ‘Opportunistic cancers’. When this happens in someone with HIV, they are said to have an AIDS-defining illness.

    The 5 most common AIDSdefining illnesses are:

    1. Pneumocystis carinii pneumonia
    2. Esophageal candidiasis
    3. Kaposi sarcoma
    4. Mycobacterium avium–intracellulare complex
    5. Cytomegalovirus retinitis.

    Furthermore, a patient with AIDS may experience the following:

    • nausea
    • vomiting
    • persistent diarrhea
    • chronic fatigue
    • rapid weight loss
    • cough and shortness of breath
    • recurring fever, chills, and night sweats
    • rashes, sores, or lesions in the mouth or nose, on the genitals, or under the skin
    • prolonged swelling of the lymph nodes in the armpits, groin, or neck
    • memory loss, confusion, or neurological disorders

    It is important to note that someone with AIDS can look and feel surprisingly well but are in fact at a great risk of sudden deterioration in their health.

    Without treatment, most patients with AIDS will die within a few years. With effective treatment, most patients with AIDS will get better and survive.

    When does HIV progress to AIDS?

    A diagnosis of AIDS is made when the CD4 T cell count falls below 200 or you have an AIDS-defining illness (see previous question).

    Without treatment, chronic HIV progresses to AIDS typically in 2-10 years after getting infection. 

    However, timely diagnosis and effective treatment will stop this progression into AIDS. Patients who already have AIDS and are recieving the correct treatment will also find their CD4 count has increased to normal range.

    Can I have HIV without any symptoms?

    Yes, most people with HIV won’t experience any symptoms until their immune system is compromised over months and years. That’s why it’s important to get tested for HIV if you suspect you may have been exposed to the virus.

    There is a small group of people with HIV whose immune system does not weaken with the passage of time. The amount of virus remains undetectable even without treatment for years, perhaps life long. Such ‘Elite Controllers’ maintain a good immune system, do not need any treatment and do not pass the infection to others.


    The complications of HIV may include:

    1. AIDS
    2. Increased risk of infections
    3. Increased risk of cancers
    4. Opportunistic infections
    5. Opportunistic cancers
    6. Risk of passing the infection to newborn by the mother during pregnancy and at the time of labour (this risk is minimised by testing during pregnancy and effective treatment)

    If you are experiencing symptoms of HIV, we would recommend getting tested and begin treatment without delay.


    How do I get HIV?

    You can get HIV from:

    • Unprotected sex
    • Exposure to the HIV infected blood
      • Blood transfusion
      • Contaminated needle
    • (Rare) Mother passing the HIV virus to child during childbirth (fortunately, all pregnant women are tested for HIV during their pregnancy and therefore this is very rare in the UK).

    You can only get HIV from someone who has HIV. The question of risk becomes key as we do not always know the HIV status of your partner (and their partners).

    How do I get AIDS?

    HIV destroys CD4 T cells — white blood cells that play a large role in helping your body fight disease. The fewer CD4 T cells you have, the weaker your immune system becomes.

    You can have a HIV infection for years before it turns into AIDS. AIDS is diagnosed when the CD4 T cell count falls below 200 or you have an AIDS-defining complication.

    Who is at a greater risk of getting HIV?

    By far the greatest risk of acquiring HIV is amongst men who have sex with men and heterosexuals who have got a partner from a high prevalence country.

    Risk can also vary by sexual activity (in decreasing order of risk of transmission):

    • Anal receptive
    • Anal insertive
    • Vaginal receptive
    • Vaginal insertive
    • Oral

    These other factors can increase the risk of HIV transmission:

    • Your partner is from a country with a high prevalence of HIV
    • You have had unprotected sex with a Commercial Sex Worker (i.e. prostitute)
    • Having other STIs
    • You or your partner is Intravenous Drug User (IVDU) and share needles
    • You or your partner engages in Chemsex

    These other factors can decrease the risk of HIV transmission:

    • Use of PrEP
    • Being circumcised
    • You are a carrier of CCR5-delta 32 genetic mutation (more common in European countries)

    If you are particularly worried about the risk of getting HIV you may wish to consult our experienced clinicians who have in-depth understanding of prevalence of HIV, its transmission and prevention strategies.

    Will I pass on HIV to my family members?

    Many patients experience distressing thoughts and anxiety of passing HIV onto their family members after a potential exposure whilst waiting for test results. You can have absolute relief in the knowledge that HIV cannot be passed from any of the following:

    • kissing
    • spitting
    • being bitten*
    • contact with unbroken, healthy skin
    • being sneezed on
    • sharing baths, towels or cutlery
    • using the same toilets or swimming pools
    • mouth-to-mouth resuscitation
    • contact with animals or insects such as mosquitoes

    Can I get HIV from my partner who has got HIV?

    If your partner has an Undetectable HIV viral load with their effective treatment, then they cannot pass HIV to you.

    How can I prevent getting HIV?

    No action needed if:

    • Partner is HIV positive, on HIV treatment and has an undetectable viral load
    • Partner is known to be HIV negative

    Consider PEP and PrEP if:

    • Partner is HIV positive, on HIV treatment but viral load is detectable or unknown
    • Partner HIV positive, not on HIV treatment and has a detectable viral load
    • Partner HIV status is not known


    There are 5 types of HIV tests that we offer depending on the need of our patients. They include:

    1) Lab-based 4th Generation HIV Test

    2) Instant 4th Generation HIV Test

    3) Lab-based HIV LIA Test

    4) Xpert HIV RNA PCR Test (from 10 days post exposure)

    5) HIV RNA Viral Load Test


    Window Period

    28 days after sexual exposure (can also test from 10 days onwards, but a repeat test will be required at 28 days for conclusive results).

    Those at higher risk of HIV may also require a further test at 90 days after sexual exposure.

    Sample required

    Blood from the vein

    Time for test results

    A routine HIV test offers results in 20 minutes.

    An early detection HIV test (at 10 days onwards) offers test results in 3 hours.

    A lab-based LIA test offers results in 4 working days.


    If you have have been exposed to HIV, it is recommended you start PEP (post-exposure prophylaxis) without delay within 72 hours of exposure (the sooner the better)

    Learn more about PEP >

    If you are at high risk of being exposed to HIV, then you can take PrEP (pr-exposure prophylaxis) before sex to prevent getting HIV in the first place.

    Learn more about PrEP >

    If your HIV test is positive, we will refer you to an NHS HIV Clinic to receive treatment and ongoing support with your diagnosis.

    We will try to make this process as easy and supportive as we can.

    Learn more about HIV Treatment >

    Page reviewed by Dr. Manoj Malu (Clinical Director)

    Last reviewed date: 3 March 2020
    Next review due: 3 March 2023

    Whilst this content is written and reviewed by sexual health specialists, it is for general guidance only. It is not intended to replace the advice of your clinician.

    If you think you may have HIV

    It is important to refer to a healthcare provider as soon as possible. Our experience combined with timely detection can help put you on the right track without delay and avoid complications in the future.

    Book an appointment >