This is a glossary for the Introduction to ART. This website has a much larger glossary at this link.


The term to describe taking medication exactly as prescribed – at the right time and following any food advice.


Part of the immune system that fights an infection.


A protein found on the surface of a virus or bacteria. It is recognised by the immune system which then generates antibodies.

antiretroviral (ARV)

An HIV drug (because HIV is a retrovirus).

ART (or HAART, now rarely used)

Antiretroviral treatment

CD4 cells

A type of white blood cell that helps your body fight infections.

first-line therapy

The first combination of HIV drugs that you use. Second-line ART is your second combination etc.


A change in the structure of the virus. Sometimes mutations can lead to a drug to stop working.

opportunistic infection (OI)

An infection that occurs after your immune system has been damaged by HIV.

post exposure prophylaxis (PEP)

A one month course of HIV drugs used by an HIV negative person after a risk of HIV exposure, in order to reduce the risk of infection.

pre-exposure prophylaxis (PrEP)

When HIV negative people take HIV drugs before sex to protect against HIV.


Another word for combination.


The time after HIV infection (usually a few weeks) when your body generates an immune response to HIV.

side effect

A secondary effect of a drug other than the reason it is prescribed.

therapeutic drug monitoring (TDM)

A test to measure the levels of a drug in your blood.


The term for the degree to which a drug can cause side effects.


Someone who has previously used HIV treatment.


Someone who has never taken any anti-HIV treatments before. People who are treatment naive can have drug resistance if they were infected with a drug resistant strain of HIV.


A type of body fat related to cholesterol.

viral load test

A test to measure the amount of HIV in blood but which can also check levels in other compartments like genital fluid, semen or spinal fluid. Tests can only measure down to certain levels (i.e. 50 copies/mL).

viral rebound

When viral load increases above detectable levels on treatment.

wild-type virus

HIV that has not developed any mutations. This is usually, but not always, the virus that you are first infected with.

Last updated: 1 October 2019.