Protect Yourself Expand Condoms Condoms are one of the most effective way of preventing HIV (and STI) infection via vaginal and anal sex as well as oral sex. They should be put on before any sexual contact as HIV can be passed on through pre-come, semen (cum) and vaginal fluid. PrEP PrEP stands for Pre-Exposure Prophylaxis and is the use of HIV medication to prevent someone who is HIV negative from becoming HIV positive. PrEP can be purchased from Iwantprepnow. PEP PEP stands for Post-Exposure Prophylaxsis and can stop HIV infection after the virus has entered the body. It is not guaranteed to work but has a very high success rate. PEP must be started no later 72 hours following the exposure to HIV. PEP can be accessed from your local sexual health clinic (GUM) or Accident and Emergency department. U=U People living with HIV can help prevent the transmission of HIV by ensuring excellent adherence to medication and maintenance of an undetectable viral load. This is referred to as undetectable=untransmittable.