HIV-related illnesses

Thanks to HIV treatment, many people with HIV in the UK will never develop a serious illness because of HIV. Nowadays, routine illnesses and treatment side-effects cause more illness in people with HIV than conditions that are traditionally thought of as HIV-related.

However, there are still about 800 new AIDS diagnoses in the UK every year. The most common are PCP (a type of pneumonia) and tuberculosis, each seen in about 200 people. Cases of these illnesses often occur in people who are unaware that they are HIV positive, and whose immune system is already seriously damaged. Often people are only diagnosed with HIV because they are so unwell with these infections.

Most illnesses are caused by one of the following:

  • A virus. These are simple organisms which reproduce using the building blocks of your own cells. Some pass quickly and of their own accord; others can be difficult to treat.
  • Bacteria. These are single-cell organisms that can be treated with drugs (antibiotics).
  • Parasites. These are organisms that live on or in a host and get their food from or at the expense of their host. Three main classes of parasites cause disease in humans: protozoa, helminths, and ectoparasites.
  • Fungi. These include yeasts and other organic growths; some types can cause illness, ranging from mild illnesses to serious one.
  • Cancers. These develop when the body’s own cells start dividing and reproducing out of control and become a tumour.

It’s possible that you have already been infected with the organisms that cause many of the illnesses listed in this section. This is because they are very common across the population and only cause problems if the immune system is damaged and unable to keep them in control. Even then, there are often effective preventive treatments to stop the illnesses flaring up, known as prophylactic treatment or prophylaxis.

Taking HIV treatment normally means that the immune system becomes or stays strong enough to prevent HIV-related illnesses happening in the first place, or from coming back again if you have already experienced them.

Candidiasis (thrush)

This is caused by a fungus (Candida) that can affect wet and warm surfaces, such as mucous membranes in the mouth, throat, vagina, anus and top of the penis. It can cause white clumps or red patches to form, and can be painful. Treatments vary depending on its severity, and are usually very effective. You can get mild candidiasis even with quite a high CD4 cell count (under 500), but it is more common in people with a low CD4 cell count and in pregnant women.

Cervical cancer

Since the mid-1990s, cervical cancer has been an AIDS-defining condition. Doctors have noticed an increase in the incidence of cervical cancer in people with HIV since effective HIV treatment became available, probably because women with pre-cancerous changes in their cervix are now living long enough for this to become a problem. It's nevertheless important to remember that cervical cancer is still rare in women with HIV, and that pre-cancerous cell changes in the cervix can be detected with regular cervical screening (Pap smears). Women with HIV are recommended to undergo cervical screening on diagnosis with HIV, six months later, and then every year after that. This is more frequently than the recommended screening cycle for women without HIV.

Cervical intraepithelial neoplasia (CIN) is a term used to describe changes in the squamous cells of the cervix. These changes are graded CIN I, CIN II, and CIN III according to severity. CIN doesn't always lead to cervical cancer – often CIN I goes away by itself. CIN II and III will require localised treatment. This treatment will help prevent CIN developing into cervical cancer.

Vaccines against the strains of human papillomavirus (HPV) associated with cervical (and anal) cancer have been developed. The vaccines work best if given before a person becomes sexually active and, at the moment, UK vaccine strategies at targeted at school-aged girls. There’s emerging evidence, however, that their use could also be beneficial for young gay men and people with HIV.

CMV (cytomegalovirus)

Cytomegalovirus (CMV) is a member of the herpes virus family, and can be transmitted sexually, through blood or saliva, and from mother to child before or during birth and through breast milk. It can affect the eyes, gut, lungs and nervous system.

Many people are infected with CMV, but it doesn't cause any problems as long as they have a reasonably strong immune system. Illness caused by CMV is now very rarely seen in people with HIV in this country because of the effectiveness of HIV treatment.

When CMV does become a problem, it tends to be in people with very low CD4 cell counts (below 50). If not treated early, it can cause very serious problems, such as damaged vision.

One of the best treatments for people with or at risk of CMV is HIV therapy as this will strengthen the immune system so it is able to fight the infection.

There are also specific treatments for CMV, including an effective oral treatment, valganciclovir (Valcyte). People with CMV may take low doses of CMV treatment to prevent the infection from reactivating.

Cryptococcal meningitis

Cryptococcus is a fungus found in bird excrement, or in soil contaminated by it. In humans, it usually infects the lungs, causing a chest infection, but can quickly spread to the meninges (the lining of the brain) causing fever, headache, stiff neck and confusion. A lumbar puncture is needed to diagnose this condition, called meningitis, properly. Cryptococcal meningitis usually only occurs in people with very advanced HIV disease, and once again, thanks to HIV treatment, it is very rarely seen in the UK.

Different treatments are used depending on the severity of the infection, and in very severe cases these drugs can have quite severe side-effects. After recovering from meningitis, it is important to take prophylactic treatment to stop it coming back. People can usually stop this once their CD4 cell count has risen and their immune system has recovered.


Cryptosporidiosis, often abbreviated to 'crypto,' is caused by a parasite that gets into the gut. It is found in soil, food, water, or surfaces that have been contaminated with infected human or animal faeces (poo). You can be infected through animal-to-human contact, or contact with an infected person, by drinking or eating contaminated water or food, or by swimming in contaminated water (for example, in lakes or rivers). See Daily health issues for more information on avoiding infection if you have a low CD4 cell count.

 Cryptosporidiosis causes watery diarrhoea, which can lead to very rapid weight loss. It can also infect the liver, causing inflammation.

Cryptosporidiosis often clears up by itself after a few weeks in people with healthy immune systems. It will be unpleasant but not serious if you are doing well on HIV treatment, or aren't taking anti-HIV drugs but have a high CD4 cell count. Although many drugs can be used to treat it, none are completely effective. Anti-diarrhoea and rehydration treatments will help reduce the effect of the symptoms.

If your CD4 cell count is low, you may become more seriously ill. Strengthening your immune system through HIV treatment is the most effective treatment. If you have crypto, it is very important to keep your fluid intake up. It may also be wise to see a dietitian to make sure that you are getting enough nutrients from your diet.

HIV-associated brain impairment

If left untreated, HIV can have a direct effect on the central nervous system (the brain and spinal cord). Before effective HIV treatment, people with advanced HIV disease sometimes developed a form of dementia as a result.

Nowadays, in countries like the UK where HIV treatment is available, dementia in people with HIV is extremely rare. The cases of dementia that are now seen often involve people who have their HIV diagnosed very late or when their CD4 cell count is very low (under 50) and they are extremely unwell because of HIV.

Symptoms can include changes in behaviour, co-ordination, memory, thinking and reasoning, from mild to more severe.

HIV treatment, which strengthens the immune system and reduced the amount of HIV in the central nervous system, can often reverse the effects of HIV-related dementia.

There’s a lot of debate about the risk of mild cognitive impairment for patients with HIV. Some studies have found a high prevalence of this condition, even in patients taking HIV treatment. However, the symptoms are often so mild that they go unnoticed and don’t affect day-to-day life.

It is important to remember that other illnesses, such as hepatitis C, can cause brain impairment and that some of the symptoms of depression, stress, alcohol or drug use or lack of sleep can be very similar to those of neurocognitive impairment. Also, the risk of developing dementia becomes higher for everyone as they get older, especially over the age of 65.

Talk to your doctor if you are concerned about your memory or any other functions.

Kaposi’s sarcoma

Kaposi’s sarcoma (KS) is a cancer that occurs most commonly on the skin, but can also affect the organs and intestines. It is caused by a type of herpes virus that is sexually transmitted. Most cases of KS in this country have been seen in gay men, although cases are also seen in people of African origin.

KS looks like purple, brown or black marks on the skin. These can look like bruises, bites or other types of infection, so a biopsy of the affected area is needed to confirm KS.

KS normally develops when you have a low CD4 cell count. The best way of treating it is to boost the immune system. HIV treatment regimens based on either protease inhibitors or non-nucleoside reverse transcriptase inhibitors (NNRTIs) have been shown to be equally effective at getting rid of KS. Individual lesions on the skin can be frozen off, and KS affecting the internal organs or intestines can be treated with chemotherapy or radiotherapy.

It is possible to develop KS even with a higher CD4 cell count. Unlike the KS seen in the days before HIV treatment became available, this form of KS is not dangerous. KS is caused by a herpes virus – HHV8 – and doctors think that low-grade and long-term suppression of the immune system allows an 'indolent' form of KS, similar to that seen in older HIV-negative people, to develop.


This is cancer of the lymphatic system: the body’s internal drainage system. It is normally seen in the lymph nodes, which swell up, but it can spread throughout the body. Symptoms include night sweats and fevers, weight loss and tiredness, but remember that many infections can cause these symptoms as well as swelling of the lymph nodes.

There are a number of different types of lymphoma, identified by the type of cells affected, the type of cancer cells they develop into, and the way the cancer spreads.

Hodgkin’s lymphoma (or Hodgkin’s disease) tends to spread slowly through the lymph system. Hodgkin’s lymphoma is not an AIDS-defining illness. The treatment of Hodgkin lymphoma is usually very successful

Every lymphoma that isn’t Hodgkin’s lymphoma is classed as non-Hodgkin’s lymphoma (NHL). There are many different types; some develop quickly, and others develop very slowly and may not need treatment for months or years. Non-Hodgkin’s lymphoma is an AIDS-defining cancer.

Epstein-Barr virus (EBV), the same virus that causes glandular fever, causes the majority of NHL and all cases of Hodgkin’s lymphoma in people living with HIV. Most adults have been infected with EBV at some point, usually without symptoms.

Lymphoma has become a lot less common in people with HIV since effective HIV treatment became available. When it does develop, it can often be successfully treated by starting or staying on anti-HIV drugs and by courses of chemotherapy or radiotherapy.

Rarely, a non-Hodgkin lymphoma will develop in the brain. This is called a CNS (central nervous system) lymphoma, and it is sometimes associated with having a weakened immune system.

Mycobacterium avium intracellulare

Mycobacterium avium intracellulare (MAI) is a bacterium similar to tuberculosis. It can be caught from soil or tap water. It only affects people with very severely damaged immune systems, when it can cause weight loss, fever and diarrhoea.

If you have a very low CD4 cell count, your doctor might recommend that you take preventive treatment (prophylaxis) to stop you getting MAI.

There are a number of treatments against MAI, but their success varies. As with many AIDS-defining illnesses, the best treatment is often to strengthen the immune system using HIV treatment. MAI is now very rare and, once again, this is largely thanks to the use of HIV therapy.

PCP (pneumocystis pneumonia)

PCP and tuberculosis are the two most common AIDS-defining illnesses in the UK. Most PCP cases are seen in people who did not know that they had HIV until they become unwell with PCP. Thanks to HIV treatment, PCP is now a very rare infection in other HIV-positive people.

PCP is a fungus that lives in the lungs and causes inflammation in a person who has a damaged immune system. PCP can be a very dangerous infection if not treated early, so you should always tell your doctor if you have a persistent dry cough and shortness of breath. Other symptoms include fever and night sweats.

There are highly effective treatments against PCP, the most common being cotrimoxazole (Septrin). For some people, cotrimoxazole causes an allergic reaction, but this tends to be mild when it is used as PCP prophylaxis. To avoid this, your doctor may desensitise you to the drug by giving you a progressively larger dose each day over a number of days.

PCP rarely develops in people whose CD4 cell counts are above 200. If your CD4 cell count is below or around 200, you may be advised to take antibiotics every day to stop you getting PCP. This is called PCP prophylaxis. You will need to take it if you have a low CD4 cell count, even if you are taking HIV treatment, until your immune system strengthens.  PCP prophylaxis also protects against toxoplasmosis (see below).


This means that you have a low number of platelets in your blood – small cells that help your blood to clot. The condition can cause bruising and, in serious cases, internal bleeding.

As it is often caused by HIV itself, the most effective treatment is HIV therapy. It is very important not to take anti-inflammatory drugs such as ibuprofen, as they can make the condition worse and cause internal bleeding.


Toxoplasmosis, or ‘toxo’ for short, is caused by a parasite transmitted in raw or undercooked meat or unwashed fruit and vegetables. Cat faeces (poo), and soil or cat litter contaminated with infected faeces, also pose a small risk. See Daily health issues for more information on avoiding infection if you have a low CD4 cell count. It is also very important to avoid infection with toxoplasmosis if you are pregnant, as toxo can be passed on to your baby and can cause more serious health problems (congenital toxoplasmosis).

It is a common infection, but in people with a healthy immune system it causes only mild, flu-like symptoms or no symptoms at all. In people with a weakened immune system, toxoplasmosis can cause damage to the eyes (ocular toxoplasmosis), and cysts to form on the brain (cerebral toxoplasmosis), leading to headaches, fever, drowsiness and fits. Without treatment, these can become very severe and lead to coma.

Serious toxoplasmosis disease is now very rarely seen in people with HIV, thanks mainly to HIV treatment. It only develops in people with weak immune systems, so the best prevention method is to be on HIV treatment. But cases of toxo were falling even before effective HIV therapy became available. This is because the drug used to treat PCP, cotrimoxazole (Septrin), is also effective against toxo, and people who take small doses of cotrimoxazole to protect them from PCP will also be protected against toxo.

Tuberculosis (TB)

TB and PCP are the two most common AIDS-defining illnesses seen in the UK. In many cases, HIV was only diagnosed in some of these people because they became ill with TB. Worldwide, TB is the leading cause of illness and death in people with HIV.

TB is caused by a bacterium called mycobacterium tuberculosis. It is a very serious infection, which usually affects the lungs, causing fever, coughing, chest pain and weight loss. It can also spread to other parts of the body.  TB that causes symptoms is called ‘active’ TB. Active TB can cause your HIV viral load to rise, but it should go down again once your TB has been treated.

It is possible to be infected with TB and not be ill. This is called ‘latent’ TB. But the illness can reappear in the future, sometimes years later. This is known as ‘reactivation’ TB. People whose immune system has become weakened are more likely to be ill with TB, either when they are first infected or through reactivation TB.

Unlike nearly every other AIDS-defining illness, you can become ill with TB even when you have a relatively high CD4 cell count.

TB can be cured. It is treated with a combination of antibiotics, which are normally taken for six months. These have to be taken exactly as prescribed, or you run the risk of developing drug-resistant TB. If you have latent TB, it may be recommended you take TB treatment as prophylaxis, to reduce the risk of becoming ill in the future.

The recommendation on when to start HIV treatment, if you are also starting TB treatment, will depend on what your CD4 cell count is.

There is a vaccine against TB, but it is not recommended for people with HIV as it is a ‘live’ vaccine. It is important to avoid close contact with people who have active TB until they are non-infectious. If you think you have been exposed to TB, you should see your doctor as soon as possible.

For more information on TB, you can read the free NAM booklet HIV and TB, which is available from NAM or from HIV clinics, or can be downloaded from You can contact NAM on 020 7837 6988 or by email at

This content was checked for accuracy at the time it was written. It may have been superseded by more recent developments. NAM recommends checking whether this is the most current information when making decisions that may affect your health.
Community Consensus Statement on Access to HIV Treatment and its Use for Prevention

Together, we can make it happen

We can end HIV soon if people have equal access to HIV drugs as treatment and as PrEP, and have free choice over whether to take them.

Launched today, the Community Consensus Statement is a basic set of principles aimed at making sure that happens.

The Community Consensus Statement is a joint initiative of AVAC, EATG, MSMGF, GNP+, HIV i-Base, the International HIV/AIDS Alliance, ITPC and NAM/aidsmap

This content was checked for accuracy at the time it was written. It may have been superseded by more recent developments. NAM recommends checking whether this is the most current information when making decisions that may affect your health.

NAM’s information is intended to support, rather than replace, consultation with a healthcare professional. Talk to your doctor or another member of your healthcare team for advice tailored to your situation.