 Pre-exposure prophylaxis, or PREP, is an HIV prevention strategy where an HIV negative person takes a daily pill to reduce their risk of contracting HIV. It's important to note that PREP is not the same as PEP, or post-exposure prophylaxis, which is a month-long treatment regimen given to individuals within 72 hours after exposure to HIV to prevent infection from taking hold. The only currently approved PREP regimen is Travada, a two-drug combo, which blocks an enzyme called HIV-reversed transcriptase. HIV relies on this enzyme to make new copies of itself, so Travada prevents the HIV virus from multiplying and establishing infection in the body. Because PREP blocks an HIV enzyme, it protects against HIV infection, but it does not prevent against pregnancy or other sexually transmitted infections, or STIs. Therefore, people taking PREP should also get regular HIV testing to make sure they haven't been recently infected, as well as STI testing and treatment if necessary. PREP has been proven to reduce the risk of HIV infection in gay and bisexual men, transgender women and heterosexual men and women, as well as people who inject drugs. PREP does not treat HIV. It's meant to prevent HIV from establishing infection, so it should not be taken by someone who already has HIV. People who want to start PREP must first be tested for HIV infection. PREP has made a lot of headlines over the last two years, and the messages haven't always been clear. Let's look at three myths about PREP and see what the facts really are. Myth number one, PREP doesn't work. In the large IPREX study of PREP in gay and bisexual men and transgender women, researchers found an overall 42% reduction in HIV transmission. However, when the researchers looked at levels of travada in the blood samples, they found that for people who took four PREP pills per week, protection was approximately 96%. For people who took PREP daily as directed, protection was estimated at more than 99%. So the take-home message, PREP works if you take it as prescribed, every day. Myth number two, PREP causes bad side effects. Some people in PREP studies have reported side effects such as nausea, headaches, or weight loss in the first few weeks of taking PREP. Most of these side effects went away on their own or when PREP was stopped, and the majority of people didn't have them at all. For example, one clinical trial reported moderate nausea only 22 times among the 1,251 people assigned to take PREP over a study period of more than two years. A recent analysis showed that some people taking PREP can have a slight increase in searm creatinine, an indicator of reduced kidney function. But these levels returned to normal after PREP was stopped. Just to be safe, people who take PREP should have regular monitoring for kidney health. Another analysis found a slight loss in bone mineral density in study participants taking PREP, although this bone loss did not worsen with long-term use. Preparation was chosen for use as PREP in part because it is safe and well tolerated. Like most drugs, some mild side effects are possible, but again, side effects reported with PREP went away over time or when PREP was stopped. Also there are other drugs currently in clinical trials that may have fewer side effects. Myth number three, PREP is impossible to get. PREP is available by prescription from doctors, nurse practitioners and physicians assistants, and most health care plans cover PREP. For insurance, Travada PREP can cost upwards of $1800 per month, but few people actually pay this full sticker price. There are medication assistance programs through Gilead Sciences that may be able to cover some or all of the costs of PREP, whether or not you have insurance. Keep in mind that depending on how you are accessing PREP, it may take several weeks to get your prescription filled the first time. Of course, PREP is not the only way to prevent HIV infection. When used correctly and consistently, condoms are an important tool for reducing HIV risk, as well as preventing against other STIs and pregnancy. For people who do not use condoms every time they have sex, PREP provides effective protection against HIV. The choice to use PREP, like the choice to use condoms, is personal. The important thing is to find an HIV prevention strategy that works for you. This video has been provided to you by Eureka Science in collaboration with Beta of the San Francisco AIDS Foundation. To learn more about HIV treatment and prevention, visit beta at beta-blog.org. Thank you for watching.