PEP

PEP stands for Post-Exposure Prophylaxis. It is a four week long course of antiretroviral drugs. The sooner after exposure to a possible HIV incident the better, and after 72 hours it is unlikely to be effective. The evidence that it works is "non-conclusive" but it appears it does work some of the time and is usually used as a last resort, so safe sex is best sex. PEP can be obtained from any doctor that specialises in the area of HIV/AIDS and some GPs, as well as the emergency department of a hospital and sexual health clinics.
It comes with a variety of side effects depending on what drugs are used, but the general lot of rash, nausea, vomiting, fatigue and diarrhoea are common, then again some people don’t experience any side affects.
Each drug costs about $22.40 for the four week course, and usually at least two drugs are used. All the drugs must be completed for the 4 week course and then the patient must return to get testing on the effects of the PEP at intervals of approximately 3 months for a year, and a month after the course. This is both to check whether the person has it and to also collect data on the effectiveness of PEP.
http://www.health.nsw.gov.au/sexualhealth/pep.html