Diagnosed with HIV at a low CD4 count

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Key points

  • A low CD4 count means that HIV has weakened your immune system and may be making you ill.
  • HIV treatment will strengthen your immune system and extend your life.
  • While your CD4 count is low, you may also need to take antibiotics to prevent infections.

HIV treatment is recommended for everyone who has HIV, but it is especially important for people with a low CD4 count. This indicates that HIV has weakened their immune system to such an extent that they are at risk of serious illnesses.

Every year several thousand people learn that they are HIV positive when their CD4 count is already below 350 (two in five of all people diagnosed in the UK in 2018).

If you are diagnosed with HIV with a low CD4 count, you will be recommended to start HIV treatment very soon or even straight away. You may need additional treatment and monitoring, but there is a good chance that you will respond well and your immune system will start recovering.

The immune system and HIV

The immune system's different cells work together to protect the body against pathogens such as viruses and bacteria.

The human immunodeficiency virus (HIV) mainly infects the CD4 cells in the immune system. Over years of untreated HIV infection, CD4 cell numbers usually drop gradually, but constantly, and the immune system is weakened. If nothing is done to slow or halt this destruction, it becomes unable to fight infections and you become ill.

Antiretroviral drugs interrupt this process. The aim of treatment is to reduce levels of HIV in your body (often called your ‘viral load’), so your CD4 count increases and your body’s ability to fight infections improves.

Starting HIV treatment after diagnosis

The sooner you start to take HIV treatment, the sooner you can benefit from it. HIV treatment will strengthen your immune system, reduce the amount of HIV in your body and prevent illnesses from occurring. Effective HIV treatment also helps prevent you from passing HIV on to someone else.

If your CD4 count is below 200 your doctor will recommend starting HIV treatment immediately. With a CD4 count below 200 your body is vulnerable to opportunistic infections. These are infections the immune system can usually prevent on its own but with a low CD4 count the immune system is not able to fight them off. Opportunistic infections can be very serious and cause potentially life-threatening illnesses.

To prevent the development of these infections you may also need to take antibiotics (a treatment called prophylaxis). Once your CD4 count has increased to above 200, the prophylaxis treatment will be stopped. If you are already ill with an infection, you may start treatment for this before you start HIV treatment.

How effective is HIV treatment in people with low CD4 counts?

HIV treatment is highly effective. Many people's CD4 count will start to climb after starting treatment. Long-term HIV therapy can result in your CD4 count returning to the expected level for your age. Once your CD4 count improves, with continued treatment and care, your life expectancy is very good.

Other factors, such as age, viral load, genetic make-up, lifestyle and quality of health care will also affect your future health and life expectancy

After starting HIV treatment, some people’s CD4 cell counts do not increase, or rise very slowly, even though their viral load is ‘undetectable’. This can mean they are at greater risk of becoming ill and of dying of HIV-related illnesses. They may also be at greater risk of developing heart disease and cancers.

If this is the case, it is very important that you receive careful health monitoring so that any developing health problems can be detected and treated early.Your lowest-ever (also called ‘nadir’) CD4 count may have an impact on your long-term health, even if your immune system has since recovered. Current data suggests that having once had a very low CD4 count is associated with a slightly higher chance of developing some health problems in the future.  

Co-infection with TB and IRIS

The decision when to start HIV treatment may be more complicated if you have tuberculosis (TB). The British HIV Association (BHIVA) recommends that all individuals with TB are offered HIV treatment as soon as is practicable and within 8 to 12 weeks of the TB diagnosis. However, in some situations, starting HIV treatment earlier may be beneficial. For example if your CD4 count is below 50, BHIVA recommends starting HIV treatment within two weeks, as soon as you can tolerate your TB treatment.


CD4 cell count

A test that measures the number of CD4 cells in the blood, thus reflecting the state of the immune system. The CD4 cell count of a person who does not have HIV can be anything between 500 and 1500. When the CD4 count of an adult falls below 200, there is a high risk of opportunistic infections and serious illnesses.

immune system

The body's mechanisms for fighting infections and eradicating dysfunctional cells.

tuberculosis (TB)

A disease caused by the bacterium Mycobacterium tuberculosis. There are two forms of TB: latent TB infection and TB disease (active TB). In people with HIV, TB is considered an AIDS-defining condition. 



The determination that a patient has a particular disease or condition, through evaluation of their medical history, clinical symptoms and/or laboratory test results.


How well something works (in real life conditions). See also 'efficacy'.

After starting HIV treatment you may develop a condition called immune reconstitution inflammatory syndrome (IRIS). This is where someone, soon after starting HIV treatment, seems to have worsening symptoms of another infection or disease, such as TB. In fact, IRIS is thought to be caused by an improvement in the immune system’s ability to respond to infections. Your doctor will make a decision about how best to treat IRIS, but it is likely you will stay on HIV treatment unless you become seriously ill.

There are also possible interactions between certain anti-HIV drugs and TB drugs. HIV medications which do not have interactions with TB treatments should be used if you are also diagnosed with TB.

Having a diagnosis of AIDS

Acquired immune deficiency syndrome (AIDS) is the name used to describe a range of illnesses (chiefly infections and cancers) which can develop when someone’s immune system has been significantly weakened by HIV.

Depending on where you live, the way an AIDS diagnosis is given will vary. In some countries, someone will be given an AIDS diagnosis if they develop an AIDS-related illness. In others you will be given an AIDS diagnosis if your CD4 count is below 200. 

Being diagnosed with AIDS does not mean that your health will continue to deteriorate. Many people diagnosed with AIDS have become healthy again, with good treatment and care.

What can you do to look after yourself?

The most important thing is to start HIV treatment, and to take it exactly the way you are advised to (this is often called adherence).

Attend your HIV clinic for regular check-ups. These monitor how your treatment is working, with regular screening for other health problems. Having a good relationship with your healthcare team is important, so that you feel able to be honest about your health, lifestyle, adherence and any other issues, to help you receive the best possible care and support.

Register with a GP (family doctor) for non-HIV-related health problems. GPs can give you an annual flu vaccination (recommended for people with a weakened immune system), and provide advice on lifestyle factors that help keep you well, including healthy eatingexercise and giving up smoking.

While your CD4 count is low (under 200), ensure your drinking water is free from infection and take extra care in preparing and storing food to avoid food poisoning. Be careful to avoid infections if you are handling animals or gardening. Your healthcare team can talk to you about any risks and give you advice.

"Once your CD4 count improves, with continued treatment and care, your life expectancy is very good."

Sexual health

Taking care of your sexual health to protect yourself and any partner(s) is important. Condoms are a very effective method of preventing HIV transmission. Being on effective HIV treatment and having an undetectable viral load means that you cannot pass on HIV.

Mother-to-child transmission

If you are diagnosed with HIV while you are pregnant, it is extremely important you receive the right HIV treatment and care as soon as possible. Even if you are diagnosed late in pregnancy, this can prevent your baby from being infected. You can find more information on mother-to-child transmission here.

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