What is prep and how does it work?
PrEP is the most powerful prevention tool currently available for people at risk of HIV infection. In people with high adherence to PrEP medication, it reduces the risk of acquiring HIV by 99%.
This compares to an HIV risk reduction of 70% for men who have sex with men (MSM) and 80% for heterosexuals who choose consistent condom use alone to prevent HIV infection. In 2015 the World Health Organisation declared that PrEP should be offered as an additional HIV prevention option to all populations at substantial risk of acquiring HIV.
In its current form, PrEP involves combining two antiretroviral drugs, tenofovir and emtricitabine, into a single tablet. PrEP is usually taken daily, but may be used just as effectively by MSM in an “on demand” fashion, taking tablets before and after sex.
What about side effects?
PrEP is generally well tolerated; in one study approximately 17% of people experienced mild side effects. These included headache, fatigue and gastro-intestinal upset within the first few weeks of starting PrEP.
These side effects mostly resolved over a few months. Only 5% of people ceased PrEP because of adverse effects. PrEP does cause a small decline in the health of the kidneys and bones, but these changes are reversible when PrEP is ceased.
People receiving PrEP see their clinician every three months to test for HIV and other sexually transmitted infections (STIs) and to monitor their overall health.