You are here

HIV & AIDS glossary

word cloud of HIV related terms


Adherence means taking HIV treatment exactly as you are advised to by your healthcare professional (including what time of day, how often, with or without food, and so on). Poor adherence can lead to drug resistance which means your treatment will stop working. It’s particularly important to make sure you don’t run out of drugs, as a break in treatment is dangerous.


AIDS stands for Acquired Immune Deficiency Syndrome and is a set of symptoms and illnesses that occur at the very final stage of HIV infection. It’s diagnosed when someone’s immune system is severely damaged, and can no longer fight off infections. AIDS and HIV are not the same.

Antiretroviral drugs (ARVs)

ARVs are drugs used to treat HIV and stop it from replicating in the body. ARVs keep the virus at a low level in the body, strengthen the immune system, and reduce the likelihood of passing HIV on. Effective treatment can reduce the virus to undetectable levels.

Antiretroviral treatment (ART)

ART is the treatment for HIV – a combination of three or more antiretroviral drugs that target different stages of the HIV lifecycle.

CD4 count

Your CD4 count is the number of CD4 cells (or T-helper cells) in your blood, measured by a simple blood test. This tells you how healthy your immune system is – your CD4 count should go up when you have HIV treatment. It’s often talked about at the same time as viral load (the amount of HIV virus in your blood). Generally when your CD4 count is high, your viral load is low and vice versa.


Chemsex involves using drugs to enhance sex. It can involve groups (including larger party settings), couples or lone masturbation. The main drugs used for chemsex are GHB, mephedrone and crystal meth.


Circumcision is the removal of the foreskin from the penis.

Voluntary medical male circumcision (VMMC) reduces the risk of HIV for men who have sex with women by 60%. The World Health Organization and UNAIDS recommend VMMC as an HIV prevention tool in countries with a high HIV prevalence among the general population – mainly in East and Southern Africa.


Co-infection is when someone has more than one serious infection at the same time. For example, when a person with HIV also has tuberculosis (TB), they are said to have an HIV/TB co-infection. This can make treatment for both infections more difficult, but also more important.


Comorbidity describes someone who has two or more diseases or health conditions at a time. For example, a person with HIV may also have high blood pressure.


Contraception helps couples to avoid getting pregnant or plan when to get pregnant. There are many different types, including hormonal, long-acting reversible contraception and condoms.

Digital health

Digital health refers to the use of digital technologies to deliver or enhance health services and information.


When a person tells someone that they’re HIV-positive. Although the word 'disclosure' has been used for a long time, it is now preferable to use the words 'sharing' or 'telling'. This is because 'disclosing' can often reinforce stigmatising beliefs that a person has done something wrong if they are living with HIV.

Drug resistance

If someone with HIV doesn’t take their antiretroviral treatment properly, the drugs may become unable to control the virus, which can cause the treatment to stop working – this is called drug resistance. It’s also possible for someone who has developed a drug-resistant strain of HIV to pass it on.

False negative result

A false negative result is when a person has HIV but an HIV test shows that they don’t have it. A false negative result usually happens during the window period immediately after initial infection, before current tests are able to detect it. If you test negative but think you may have HIV, you can take another test once the window period has passed.

False positive result

A false positive result is when a person does not have HIV but an HIV test shows that they do. Whenever someone receives a positive test result, they are tested again to confirm the result.

Female condom (internal condom)

A female (or internal) condom is a thin pouch that is worn inside the vagina or anus during sex. It works by forming a barrier to protect against sexually transmitted infections (STIs) including HIV, and unplanned pregnancy.

First-line treatment

First-line treatment is the antiretroviral treatment recommended for people starting HIV treatment for the first time. It’s a combination of three or more antiretroviral drugs from two different drug classes.


HIV stands for Human Immunodeficiency Virus. It attacks a person’s immune system cells, and if left untreated severely damages their immune system and their ability to fight off infections.

HIV cure

There is no cure for HIV. However, antiretroviral treatment can control the virus, meaning that people with HIV can live long and healthy lives.

HIV vaccine

There isn’t a vaccine for HIV but a number of HIV vaccine trials show encouraging results.

Male condom (external condom)

A male (or external) condom is a thin piece of rubbery material that fits over a man’s penis during sex. It works by forming a barrier to protect against sexually transmitted infections (STIs) including HIV, and unplanned pregnancy.

Mixed-status couple

A mixed-status couple is when one person has HIV and the other does not. It is also known as a serodiscordant couple, a discordant couple, or a serodifferent couple.

Post-exposure Prophylaxis (PEP)

PEP is short-term treatment that stops HIV spreading throughout the body. It must be taken within 72 hours of possible exposure to HIV, for example, after unprotected sex, to be effective.

Pre-exposure Prophylaxis (PrEP)

PrEP is a course of antiretroviral drugs that can prevent HIV infection. It’s for men and women who are HIV-negative but who may be at higher risk of HIV infection. For example, someone who has an HIV-positive partner, or is unable to negotiate condom use, or has regular sex without a condom may benefit from PrEP. When PrEP is adhered to exactly as prescribed, it eliminates the risk of HIV infection – but the risk increases significantly if doses are missed.

Opportunistic infection

Opportunistic infections are a type of infection that occur in people with a weakened immune system (for example people living with HIV).

Second-line treatment

When first-line antiretroviral drugs stop working, a person takes second-line treatment.


HIV self-testing allows you to take an HIV test in your own home or another private place. These kits are becoming more widely available and give a result in 15 to 20 minutes.


A syndemic or synergistic epidemic is the combination of two or more coexisting epidemics in a population, for example HIV and TB. Biological interactions between the coexisting epidemics make the prognosis and burden of disease worse. 

Sexually transmitted infection (STI)

STIs are infections that can be passed on when you have unprotected sex or close sexual contact with someone who already has an STI. Examples include chlamydia, genital herpes, gonorrhoea, hepatitis C and trichomoniasis. HIV is also a sexually transmitted infection although there are other ways it can be passed on.

T-helper cells

See CD4 count above.

Third-line treatment

When second-line drugs stop working, a person takes third-line treatment.

Undetectable / virally suppressed

A person living with HIV is considered to have an ‘undetectable’ viral load – or to be virally suppressed – when antiretroviral treatment has reduced the virus in their body to such low levels that blood tests cannot detect it. Having an undetectable viral load means you can’t pass HIV onto others, and your health won’t be affected by the virus. It is essential to adhere to treatment and have your viral load monitored by a health professional to make sure it stays undetectable.

Viral load

A person’s viral load is the amount of HIV virus in their blood. It is measured by a simple blood test. It can tell you how well a person’s antiretroviral treatment is working.

Window period

The amount of time it takes after infection for the body to produce enough HIV antibodies to be detected on an HIV test, in order to get an accurate result. This is between 2 and 12 weeks depending on the type of test.

HELP US HELP OTHERS is helping to prevent the spread of HIV and improve sexual health by giving people trusted, up-to date information.

We provide all this for FREE, but it takes time and money to keep going.

Can you support us and protect our future?

Every contribution helps, no matter how small.

Photo credit: Copyright AVERT

Last full review: 
17 July 2020
Next full review: 
17 July 2023
Last updated:
17 July 2020
Last full review:
17 July 2020
Next full review:
17 July 2023