with other drug users in the past six months, or has been in treatment for intravenous drug use in the past six months In the United Kingdom the BHIVA/BASHH guidelines on the use of HIV pre-exposure prophylaxis (PrEP) 2018 recommend: On-demand or daily oral Tenofovir – emtricitabine (TD-FTC) for HIV-negative MSM who are at elevated risk of HIV acquisition through unprotected anal sex in the previous six months and ongoing unprotected anal sex. On-demand or daily oral TD-FTC for HIV-negative MSM having unprotected anal sex with partners who are HIV positive, unless the partner has been on ART for at least six months and their plasma viral load is <200 copies/mL. Tenofovir (TDF) alone should not be offered to MSM. Daily oral TD-FTC for HIV-negative heterosexual men and women having unprotected sex with partners who are HIV positive, unless the partner has been on ART for at least six months and their plasma viral load is <200 copies/mL. Daily oral TD-FTC for heterosexual men and women on a case-by-case basis with current factors that may put them at increased risk of HIV acquisition. TDF alone can be offered to heterosexual men and women where FTC is contraindicated. PrEP is not recommended for people who inject drugs where needle exchange and opiate substitution programs are available and accessed by the individual. PrEP with daily oral TD-FTC for HIV-negative trans women who are at risk of HIV acquisition through unprotected anal sex in the previous six months and ongoing unprotected sex. Daily oral TD-FTC for HIV-negative trans women and trans men who have unprotected sex with partners who are HIV positive, unless the partner has been on ART for at least six months and their plasma viral load is <200 copies/mL. Other government health agencies from around the world have devised their own national guidelines for how to use PrEP to prevent HIV infection in those at high risk, including Botswana, Canada, Kenya, Lesotho, South Africa, Uganda, the Zambia, and Zimbabwe. Often, laboratory testing is required before starting PrEP, including a test for HIV. Once PrEP is initiated, individuals are asked to see their healthcare provider at least every three to six months. During those visits, providers may want to repeat testing for HIV, test for other sexually transmitted infections, monitor kidney function, and/or test for pregnancy. Individuals must test negative for HIV prior to PrEP initiation because persons infected with HIV