Though you may have never heard of them, post-exposure prophylaxis (PEP) and pre-exposure prophylaxis (PrEP) are exciting and relatively new preventative measures against HIV. However, they’re generally unknown to the public and are surrounded by controversy.

What are PEP and PrEP?

Post-exposure prophylaxis (PEP) is a four-week series of antiretroviral drugs that can be taken by HIV-free persons shortly after possible exposure to HIV in order to decrease the risk of infection. The idea behind PEP is to kill the virus while its levels are still low, before it has a chance to spread throughout the body. In order for it to be effective, PEP must be initiated as soon as possible after exposure and only within the first 72 hours.

PEP treatment was first designed for health care workers who had been stuck by needles or otherwise exposed to blood on the job; however, it can potentially be used in a variety of other situations in which exposure may have occurred, e.g. if a condom breaks.

Pre-exposure prophylaxis (PrEP) is also the use of antiretroviral medicine to prevent HIV infection; however, here it is done before possible exposure. It works much in the same way malaria prophylaxis works: a person takes the medication when they are at high risk (such as when traveling in areas where malaria is common), and the drugs prevent malaria infection should one be exposed. In other words, if the person were exposed to the virus, the medicine in the person’s system would be able to attack and get rid of it immediately before it has a chance to multiply.

PrEP isn’t approved for use yet, but some uninfected people have begun taking antiretroviral with the idea of using them as a PrEP-type of regimen, and some doctors have even begun administering antiretroviral as a kind of PrEP to their high-risk clients (such as those who consistently engage in high-risk sex without protection). As with PEP, PrEP could potentially be used by anyone.

Why Aren’t PEP and PrEP Widely Available?

There are many reasons why PEP and PrEP remain largely unknown.

First, there is the question of efficacy. So far, the use of PEP has prevented HIV in the majority of cases, but there have been times when it has failed. PrEP, on the other hand, is still being studied and is not approved for use yet. If PEP and especially PrEP are to be used on a grand scale, more studies would be needed to prove that they work, as well as when they work and what their long-term effects will be. Money and interest for research on these methods can be hard to sustain, partially because there are plenty of other methods of preventing HIV, like condom usage, that have been proven to work and are inexpensive.

Antiretroviral also have nasty side effects, such as diarrhea, abdominal pain, nausea, insomnia, headache, anemia, fatigue, muscle pain and many other uncomfortable symptoms. This is serious medication that may wreak havoc on the system and aren’t to be taken lightly. Therefore, most experts continue to encourage safe sex and lean away from dangerous habits, rather than arming them with pills that can cause many serious side effects.

Furthermore, not everyone a person has sex with has HIV, and there is usually no way of knowing the partner’s status for certain. Therefore, to give PEP to everyone who wanted it would mean a whole lot of drugs—with side effects—and, would be used on an otherwise healthy population who may not have even been exposed to the virus. Money is a factor as well. It just may not be seen as cost-effective to distribute to everyone, particularly when condoms are an effective and fairly inexpensive way of preventing HIV infection. Plus, if people were to use PEP to prevent HIV but not practice safe sex, they would still be at risk of other sexually transmitted infections.

Many fear that if PEP and PrEP were widely available, people would rely on them and not use other preventative methods, such as using condoms and other latex products. Just because taking some pills might avert HIV infection doesn’t mean it’s safe to engage in risky behavior. Especially because the behaviors that put a person at risk for HIV can also put him or her at risk for a variety of other diseases, such as hepatitis B and C, chlamydia, herpes and other sexually transmitted infections.

Additionally, there has been some controversy surrounding the studies of PEP and PrEP. For example, after great protests at the 2004 International AIDS Conference in Bangkok, Thailand, trials testing the use of PrEP in Cambodian sex workers were halted due to ethical concerns, such as lack of medical treatment for those who became infected or complaints from those who experienced side effects from the antiretroviral. While we await the conclusion to these ethical concerns so that the trials can be completed, there are other trials that are simultaneously ongoing.

What are the Arguments for Making PEP and PrEP More Available?

Many who work on the frontlines of HIV prevention believe that in some cases PEP and PrEP are simply the best option. As available as condoms are, many people still don’t use them, and in many places clean needles are difficult and even illegal to obtain. When working with people in extremely high-risk groups where nothing else works, PEP and PrEP can be a last-ditch effort to prevent HIV.

Furthermore, some people in high-risk groups have begun taking antiretroviral (both pre- and post-exposure) on their own without the supervision of a doctor. Not only is this dangerous because they are taking strong medication without being monitored, but they may not be taking them in the correct amounts to prevent HIV, and therefore may still be at risk for becoming infected. Making PEP and PrEP more accessible could avoid these circumstances from occurring and create guidelines for use that would be readily available to the public.

Where Can I Get PEP or PrEP?

If you are a health care worker exposed to blood on the job, PEP is fairly easy to obtain. Most hospitals have programs for PEP, and there is also a national hotline for clinicians who may have been exposed.

If you aren’t a health care worker, PEP can be more difficult to come by, and it is usually only available for those who may have been exposed to HIV because of “non-voluntary” activities like sexual assault.

The U.S. Department of Health and Human Serviceshas recommended the use of PEP in cases of non-occupational exposure, but only if the exposure has occurred within 72 hours and the risk is “substantial.” Substantial risk is considered “ contact of an area of the body known to be associated with acquisition of HIV (vagina, rectum, eye, mouth or other mucous membrane, non-intact skin or percutaneous contact) with a body substance known to transmit HIV (blood, semen, vaginal secretions, rectal secretions, breast milk or any body fluid that is visibly contaminated with blood) when the source is known to have HIV infection.” However, if the HIV status of the source is unknown, PEP is not guaranteed and will only be dispensed on a case-by-case basis. Therefore, it is not recommended to forego condom use or engaged in other risky behaviors and rely on PEP. The Joint United Nations Programme on HIV/AIDS has more information.

Because PrEP is still being studied, it is still unknown if, when and to whom it may become available. However, doctors in some areas who treat high-risk patients have begun administering antiretroviral for use as PrEP because they feel that they have no other choice but to do something—anything—that may decrease the risk of these patients contracting HIV. If you believe you are at high risk, the best thing to do is to consult a doctor and ask.