on-demand dosing

On-demand dosing – a term for taking medicines only at times linked to a relevant event. On-demand dosing for PrEP is also called “event based dosing” (EBD). For example, on-demand dosing for PrEP (to prevent HIV transmission) involves taking PrEP before sex and then …


outreach – a type of service which goes out to find and engage people.


organogenesis – the process of development of baby’s main organs. This period is the first 12 weeks in the womb.

opportunistic infection (OI)

opportunistic infection (OI) – an infection that occurs after your immune system has been damaged by HIV. OI chapter of the training manual.


opiate – a drug that comes from the opium poppy. Opiates include heroin, codeine and morphine.

open label

open label – this means that a patient in a trial knows which treatment they are taking.


oesophagus – part of the gut between the throat and the stomach.