The Real Deal On HIV, PrEP, and PEP

information about PrEP and PEP for HIV prevention

If you’re a sexual health nerd, read a lot of news, or have been exposed to sexual health ad campaigns lately, you’ve probably heard about pre-exposure prophylaxis (PrEP) — medication that can prevent HIV infection. You might have also heard that there’s a “morning after pill” for HIV called post-exposure prophylaxis (PEP), or heard the slogan “undetectable equals untransmittable.” What these three things have in common is that they all involve the use of anti-HIV medication (also called antiretrovirals) to prevent people from getting or transmitting HIV. Together, these methods are known as biomedical HIV prevention.

The use of medication to prevent HIV is not exactly new (PrEP has been out for a few years now and PEP has been around since the 1990s), but there’s still a major problem with misinformation and a lack of awareness. This article aims to provide you with basic knowledge about PrEP and PEP — how they work and where to get them — and to clear up some common misconceptions about medications that are used to prevent HIV.

If you need to brush up on your HIV basics (which is a great idea before reading the rest of this article!), check out our brief STI File on HIV or read our extensive HIV roundup article.

Biomedical HIV Prevention – The Basics

Most conversations about HIV prevention involve barriers – like condoms and dental dams – or behavioral changes, like having fewer sex partners, getting tested more frequently, and communicating with partners about testing and safer sex. These are important, useful, and effective strategies for preventing HIV, but for some people in some situations, they aren’t enough. Biomedical HIV prevention can be really helpful for folks who want additional protection from HIV or for folks who feel like perfect condom use or other behavior changes just aren’t realistic goals for them. It’s also important for preventing HIV in folks who have already been exposed (as sometimes happens during sexual assault, or if a condom breaks). Finally, some people are HIV-positive themselves and want to protect their sexual partners or want to start a family and have biological children who are HIV-negative.

There are four main ways in which HIV medications are used as a form of HIV prevention:

  • PrEP: A daily medication that is taken regularly (before and after exposure) to prevent HIV. It is meant to prevent HIV exposures that occur on an occasional to frequent basis. People who take PrEP might decide to take it for months or years.
  • PEP: A medication that is taken to prevent HIV after an exposure happens. It is taken within 72 hours of an exposure and continued for 28 days. PEP is not used for routine HIV prevention but in unexpected situations like sexual assault, blood exposures, or broken condoms.
  • PMTCT: PMTCT (prevention of mother to child transmission) includes methods used by HIV-positive people of any gender who want to have biological children who are HIV-negative. This includes medication taken by parents to prevent transmitting HIV to each other during conception, medication taken by the pregnant person to prevent transmitting HIV to the developing fetus, and a one-month course of medication taken by infants to keep them from developing HIV once they’re born.
  • TasP: TasP (treatment as prevention) is providing treatment to HIV-positive people not only to keep them healthy but to prevent HIV from being transmitted to other people. HIV-positive people who are on medication that successfully reduces the amount of virus in their body cannot pass HIV to others during sex. There are a couple of caveats here — different HIV medications work well for different people and they do not work immediately. For treatment to work as HIV prevention, the person with HIV needs to be on medications that work well for their body and needs to be taking them consistently and correctly (what this means is different for each medication but usually means once a day). In most people, the amount of virus in their body will be too low to transmit after two to three months of treatment.

The Big Disclaimer

The four HIV prevention strategies listed above work really, really well. We won’t understate how effective they are — every strategy we discuss in this article reduces HIV risk by over 90 percent (and, depending on which research papers you read, up to 99 percent). However, none of these medications do anything to prevent any other kind of STI and none of them do anything to prevent pregnancy.

In other words, these are useful tools for protecting your sexual health but are not a complete safer sex strategy on their own. HIV is obviously a big deal and it’s awesome to have so many ways to prevent it — especially considering that there is no cure for HIV and untreated HIV can progress to a serious, life-threatening condition. That being said, other STIs are nothing to sniff at (especially with infections like gonorrhea that are becoming increasingly resistant to antibiotics). Everyone’s situation is different, but if you’re using medications like PrEP to protect yourself from HIV, you’ll also need to consider your risk for other STIs (and possibly pregnancy) and how you’ll protect yourself. You can also get more info about your risk for other STIs and learn more about your safer sex options!

Another major disclaimer — this article mostly discusses sexual transmission of HIV, not blood-to-blood transmission. It is unknown whether PrEP protects people from getting HIV through injection drug use or whether treatment as prevention prevents people from transmitting HIV through injection drug use. If you are using injection drugs, there are still a lot of ways you can protect yourself from HIV. You can learn more about them from the Harm Reduction Coalition’s safety manual Getting Off Right.

What is PrEP?

PrEP stands for pre-exposure prophylaxis, which is a fancy way of saying that it’s a form of HIV prevention that you use to protect yourself from HIV before you get exposed (although technically, people take PrEP before, during, and after the exposure). PrEP is used to prevent HIV exposures that occur on a regular basis (like in someone who is sexually active with people who are or might be HIV-positive) and is taken as a daily medication. Since PrEP is taken every day, it’s meant to be a medication that you’d have in your body before, during, and after an HIV exposure.

The medication that is currently used as PrEP is a pill that contains two different medications (tenofovir and emtricitabine). In the United States, this pill is usually sold under the brand name Truvada, but outside the U.S. might be known by various generic names. Regardless of what it’s called, when taken once a day every day, PrEP is up to 99 percent effective at preventing HIV.

How does it work?

PrEP contains two anti-HIV medications (also known as antiretrovirals or ART) that prevent HIV from making copies of itself. In a person who is HIV-positive, these medications are used to keep the level of HIV in the body low. In an HIV-negative person on PrEP, the goal is to use these medications to stop an HIV infection from happening in the first place. When a person on PrEP is exposed to HIV, the drugs stop the virus from making copies of itself, preventing the infection from becoming established.

For PrEP to do its job at preventing HIV, it needs to first build up inside of the body until it reaches a high enough level to work. The drugs in PrEP need to be present in the parts of the body where HIV transmission happens — the lining of the rectum and the lining of the genitals (the walls of the vagina and the inside of the urethra in a penis). Because PrEP must build up in these parts of the body before it starts to work, PrEP does not provide immediate protection against HIV. You need to be on PrEP for a certain length of time before it will protect you from HIV.

How long? It depends on what type of sex you’re having. PrEP builds up faster in the lining of the rectum than it does in the genitals. If you are bottoming for anal sex (having someone’s penis inside your anus), you need to take PrEP every day for 7 days before it will protect you from HIV. In you are having other forms of genital sex (putting your penis inside someone’s vagina or anus, or having someone’s penis inside your vagina), PrEP must be taken every day for 28 days before it will protect you from HIV.

The other important thing to know about PrEP is that it’s really effective (like, 99 percent effective) at preventing HIV but only when you take it every single day. Just like with any HIV prevention strategy, there’s a difference between perfect use and actual use. In most studies of PrEP, the overall protection from HIV was between 40-75 percent — but these figures included people who skipped doses. People who took PrEP every single day had about a 99 percent decrease in their HIV risk. Missing an occasional dose doesn’t mean you lose all protection immediately, but more missed pills = less protection. This means that while PrEP can be really effective, it is not a great HIV prevention method for someone who would have trouble taking daily medication.

Who is PrEP for? And why haven’t I heard about it?

PrEP is for teens and adults of all genders and sexualities who might be at risk of getting HIV through sex. This means people who are gay, straight, bi, and queer, people who are cis, trans, and nonbinary, and people who are young and old. People who take PrEP can be:

  • Having sex with any number of people who are HIV-positive or of unknown status. A person on PrEP might have casual sex with multiple people, be in a committed non-monogamous relationship, be in a relationship with one or more HIV-positive people, doing sex work, not doing sex work, and so on. There’s no minimum number of partners you need to have to be on PrEP.
  • Having any kind of sex that can transmit HIV. PrEP works for both anal and vaginal sex and both topping and bottoming.
  • Using or not using drugs. PrEP provides protection from sexual transmission of HIV regardless of whether someone injects drugs. It’s just not known how effective PrEP is at preventing blood-to-blood transmission.
  • Using or not using hormones. PrEP works in transgender and nonbinary people regardless of whether or not they take hormones.
    Despite the fact that PrEP is meant for a wide range of people, many folks have never heard of PrEP or don’t think it’s intended for them. This is especially true of young people. The 2017 Kaiser National Survey of Young Adults on HIV/AIDS found that 74 percent of young people had never heard of PrEP. Of those who had heard of PrEP, only 18 percent believed that PrEP worked and only 26 percent believed that PrEP was something everyone who needed could access.

So what’s going on? Unfortunately, the majority of awareness campaigns around PrEP have focused on gay and bisexual cis men, and a large amount of attention has been concentrated in wealthier, white communities. In addition, it’s still a common misconception that HIV only impacts gay and bisexual men. Women are often left out of educational campaigns around PrEP and until the past few years, PrEP research studies excluded transgender people.

The result of this is that a lot of people either don’t believe that PrEP is meant for them or have never heard of PrEP at all. People who have heard of PrEP often believe that PrEP is only for gay men who have a lot of condomless anal sex with anonymous partners.

However, the fact that educational campaigns, research, and funding have focused on gay and bi cisgender men doesn’t mean other folks can’t benefit from PrEP. The CDC estimates that the number of cis women who are at high risk for acquiring HIV is about equal to the number of gay and bi cis men at risk (in fact, 1 in 5 new HIV diagnoses are in women).

Increasingly, PrEP studies are including trans women, trans men, and non-binary folks and there’s a growing body of evidence that PrEP can benefit trans folks of all genders. That being said, there’s a lot of research and advocacy to be done in this area.

Why might someone use PrEP?

The most common reason a person might decide to use PrEP is that they are at high risk for getting HIV and want to reduce that risk. Some things that increase your chance of being exposed to HIV are:

  • Having partners who are HIV-positive.
  • Using injection drugs or having sex with folks who use injection drugs.
  • Having anal and/or vaginal sex with partners whose HIV status you do not know – especially if you have multiple partners.
  • Having anal and/or vaginal sex without condoms – especially with multiple partners whose status you do not know.

Most people who take PrEP will fit into at least one of the above categories. However, there are some people with lower HIV risk who take PrEP as well. Just as it’s common for folks to use back-up methods of birth control (like using an IUD in addition to condoms), many people decide to back-up their condom use with PrEP to help them feel safer and more relaxed during sex. There are also people who take PrEP because they are anxious about HIV. Often, people who come from HIV-impacted communities — especially gay and bisexual men — have grown up with the message that they are “fated” to get HIV. Especially for people who have internalized the idea that certain kinds of sex are inherently dangerous or deadly, using PrEP can be very liberating. In addition, the fact that PrEP is an HIV prevention method that does not require cooperation from sex partners gives many people a sense of control over their own bodies — it’s a way of protecting yourself from HIV that no one else needs to know about or agree to.

Why might someone stop taking (or never take) PrEP?

Taking PrEP is not a lifetime commitment. Some people use PrEP because they’re going through a period in their life where their HIV risk is higher. They might be dating someone who is HIV-positive, or experimenting with their sexuality or just going through a more sexually active period. These types of risks typically don’t last for someone’s entire life, so when circumstances change, someone might decide to stop taking PrEP. It’s normal for all of us to have levels of HIV (and other STI) risk that increase and decrease throughout our lives, and so it’s reasonable to expect that our safer sex practices will change over time. So, there are people who take PrEP when they feel like they need it and stop taking it when it no longer feels necessary.

There are also people who start taking PrEP and then decide it’s not right for them. They might realize that their HIV risk is not really that high, or that they are comfortable with other HIV prevention methods like condoms alone. Those are totally valid reasons to stop taking PrEP. Some other (also totally valid) reasons why people might want to stop PrEP (or just not start in the first place) are:

  • Privacy issues, like worrying that a partner or family member will find the bottle of PrEP and ask about it.
  • Not being able to pay for the medication or get it refilled on time.
  • Concerns about side effects.
  • Not wanting to take a pill every day.

Stopping PrEP isn’t difficult, but it does require a check-in with a medical provider: you might be asked to keep taking the medication for a certain number of days after your last potential HIV exposure before you can stop.

It’s important to note here that problems with side effects, taking medication, paying for PrEP, or dealing with privacy are generally issues that can be solved (and we’ll talk more about problem solving later in this article). However, taking PrEP is a personal choice and no one should feel like they have to be on it — it’s one of many ways to help prevent HIV, not a one-size-fits-all solution.

How do you take PrEP?

If you decided to start taking PrEP, your first step would be having an intake appointment with a PrEP provider. This might be the person who you see for regular medical care, or it could be someone at a sexual health clinic (resources for finding a provider are at the end of this article). During your intake appointment, you’ll have a conversation about the pros and cons of being on PrEP and decide whether it’s right for you. Then, you’ll have blood and urine tests to check out your liver and kidney health and make sure PrEP is safe for you to take. You’ll also be tested for HIV to make sure you’re HIV-negative before starting PrEP and a pregnancy test if you’re capable of becoming pregnant. Most people are also offered a full STI screening during their intake.

If your labs check out, you’ll get a prescription for PrEP about a week after your initial intake visit and you’ll be able to fill it at a pharmacy and start taking the medication. Once you’re taking PrEP, you’ll keep seeing a provider every three months. During these visits, you’ll get a full STI screen, an HIV test, and a chance to check in about any side effects or other concerns you might have. If you ever decided to stop taking PrEP, you’d want to check in with your provider about this, since they might ask you to stay on the medication for a certain number of days after your last HIV exposure.

Why do you still need to get tested for HIV if you’re taking PrEP? The risk of getting HIV while on PrEP is low, but it is not zero, especially if you miss doses. Since PrEP on its own is not a complete treatment for HIV infection (and taking PrEP by itself if you actually have HIV could lead to drug resistance), it’s important to catch HIV infection early and get proper treatment ASAP.

How do you find a PrEP provider?

For many people, taking PrEP is no big deal. Especially if someone already has a regular doctor and has taken medication before, getting regular labs and taking a pill every day can feel pretty straightforward.

However, not everyone has the same access to healthcare. For young folks especially, getting on PrEP could be the first time they’ve had to find a healthcare provider, figure out how to pay for medication, and get into the habit of taking pills and having regular medical appointments. Healthcare can be seriously intimidating and confusing, but the good news is that you don’t need to figure out everything yourself — there are a ton of resources and programs out there to help you find a provider and pay for PrEP.

So to start off: who can prescribe PrEP? PrEP is not available over-the-counter: you need to get it from a medical provider (like a doctor or nurse practitioner) who can prescribe the medication and monitor your labs. This person doesn’t need to be a specialist but they do need to be familiar with PrEP and they should be someone you trust and feel comfortable talking to about sex.

You might already have someone who you see for regular health care who fits this bill. If that’s the case, great! All you need to do is make an appointment with them.

A lot of young people don’t have a regular medical provider, however, and finding a provider can be daunting if you’ve never done it before. It’s also a reality that not all medical providers are comfortable talking about sex and sexuality. Some providers might be unfamiliar with PrEP or think it’s only for very sexually active cis gay men and be reluctant to prescribe it to (for example) women and trans people. And although this should never happen, there are providers who have homophobic attitudes or who behave judgmentally towards people who ask to be on PrEP.

Luckily, you have a lot of options. Sexual and reproductive health clinics (like Planned Parenthood) are one example. Increasingly, places that provide walk-in HIV and STI testing offer PrEP and can often help you navigate tricky issues like insurance. There are several online databases of PrEP providers that you can use to find resources in your area. Finally, if you’re currently a university student, your student health center can likely either provide PrEP or refer you somewhere that does.

In some regions — especially rural areas — none of the above options may seem realistic. If you can’t find a provider who is knowledgeable about PrEP in your area and you can’t find a sexual health clinic nearby, another possible option is telemedicine. Telemedicine involves meeting with a provider over a computer, having your bloodwork done at a local lab, and getting the medication filled at a local pharmacy. This option is increasingly available in the United States.


Being your own advocate: It might feel weird to ask your doctor to do their homework, but it’s a reality that not all providers are up-to-date on sex, gender, and safer sex. Educating your provider is one way to help advocate for your health needs and get more involved in the care you receive.

If your doctor isn’t experienced with PrEP or won’t prescribe it to you because of your gender or sexuality, that doesn’t mean the conversation has to be over. There are some handy resources out there designed to help health providers learn more about PrEP. The Clinician Consultation Center provides HIV and PrEP advice to doctors over the phone and the internet. Another handy resource is the Family Planning Provider PrEP Toolkit, which provides info for reproductive health providers on providing PrEP.

If you’re trying to navigate a sticky relationship with your healthcare provider, trying to find a provider, or hoping to do some self-advocacy around PrEP, check out our article on choosing a doctor and advocating for yourself.


Paying for PrEP

We won’t sugarcoat this — health insurance and health care costs can be really complicated and intimidating and a lot of folks worry that PrEP will be too expensive to afford. There’s a grain of truth to this — in the United States, for example, where health care is very expensive and drug companies get to charge as much as they want for medication, the out-of-pocket cost for PrEP is about $13,000 a year (though thankfully, PrEP is drastically cheaper everywhere else). However, there are programs out there to help people afford the cost of PrEP and in reality, most people pay very little (if anything) to be on PrEP.

You don’t have to deal with finding these programs on your own. Most sexual and reproductive health clinics that provide PrEP will help you figure out how to pay for it. That might look like helping you get signed up for insurance or government benefits or it might involve helping you apply for private programs that help provide medication for free. The bottom line is there are a bunch of resources (and social workers) out there that make it possible for anyone who wants PrEP to be able to afford it.

Taking a pill every day

For some folks, taking PrEP is the first time they have ever taken a daily medication. Getting used to this routine (or really, any new habit) can be hard, especially when someone has a hectic schedule or doesn’t sleep in the same place each night. If this sounds like you, don’t sweat it — there are some simple tips and tricks for getting into a daily pill-taking habit. Pill cases that have separate compartments for each day of the week can be really handy if you have trouble remembering whether you’ve taken your pill each day (setting a reminder on your phone can be helpful here, too). You can also get tiny pill boxes that fit in a pocket or on a keychain, which are useful if you usually keep your medication at home but sometimes sleep elsewhere. If these methods don’t cut it, talk to your PrEP provider about what’s going on! They can help you with more complex troubleshooting.

Dealing with stigma and judgment

Some people worry that if they’re open about taking PrEP, other people will make assumptions about their sexuality and judge them for being “promiscuous.” PrEP is tied up with a lot of things that carry serious stigma, like HIV, queer sex, non-monogamy, and condomless sex (barebacking). Although PrEP is becoming more normalized in some queer and trans communities, people of all genders and sexualities worry about being judged for taking PrEP. A common concern folks have when taking PrEP is whether to tell family, friends, or partners that they take it. There isn’t a single right way to handle disclosure and not everyone decides to be open about their PrEP use. One of the advantages of PrEP is that it’s an HIV prevention method that is under your control. No one else has to know that you take PrEP and you can make your own decisions about who you decide to tell.

If you take PrEP (or are thinking about taking PrEP) and have concerns about disclosure and stigma, you most definitely are not alone. The blog My PrEP Experience has personal stories and information about coping with these issues.

Worried that PrEP makes people stop wearing condoms?

A really common myth — even among sexual health providers and educators — is that people use PrEP as an excuse to stop using condoms, or that PrEP will lead to a rise in STIs. Rates of STIs like chlamydia, gonorrhea, and syphilis have been on the rise in the United States, especially among young women, and some folks have been quick to blame PrEP for leading to lower rates of condom use and higher rates of STIs.

The truth, however, is that some research suggests that taking PrEP does not cause people to stop using condoms and that, at least among gay cis men, condom use was already on the decline before PrEP came out. Although STI diagnoses are common among PrEP users, this is in part because people on PrEP tend to be tested more frequently — most PrEP providers require that their patients get a comprehensive STI screening every three months. In general, people who get tested for STIs more frequently get diagnosed more frequently — because you have to get tested to get diagnosed!

It is true that some people take PrEP specifically because they do not always (or ever) use condoms or because they want to stop using condoms. For the majority of PrEP users, this isn’t the case. Many PrEP patients have found that taking PrEP makes them think more seriously about their sexual health. Taking a big step to protect themselves — like starting PrEP — makes them want to take other steps to protect themselves, like using condoms or limiting their number of sexual partners. Although it makes sense to be concerned about STIs, especially in folks who might not always use condoms, there’s a good chance that part of the hype around condom use in people who take PrEP has more to do with sexual stigma than with science. It’s similar to the hype around comprehensive sexual education and birth control – people have made arguments that access to these things will make teens have lots of “risky sex,” even though we know this isn’t true.

A useful way to think about PrEP and STIs is to make an analogy with birth control methods like the ring, shot, IUD, or pill — none of those birth control methods prevent HIV or STIs, but a lot of folks use them to provide extra security in case a condom breaks. Being safer sex advocates doesn’t mean we would discourage anyone from using birth control methods that don’t protect against STIs. PrEP is often used as a back-up HIV protection in addition to condoms, just as many people back-up their condom use with additional forms of birth control. And even when people do decide to have sex without condoms, PrEP protects against HIV — which is a pretty big deal.

Side effects

Side effects from PrEP fall into two categories: short-term and long-term. Short-term side effects are things you might experience in your first couple weeks of taking PrEP, but that eventually go away. About 90 percent of people who take PrEP do not experience any side effects at all. The remaining 10 percent have mild side effects including stomach aches, headaches, trouble sleeping, nausea, and diarrhea. These side effects are also known as “start-up syndrome” and go away within the first month.

Long-term side effects are things that you might experience after taking PrEP for many months. These include a decrease in bone density and a decrease in kidney health. Both of these side effects resolve when a person stops taking PrEP. For the vast majority of people on PrEP, any changes in bone and kidney health are not major enough to cause health problems (for example, people on PrEP don’t get broken bones more often than people who do not take PrEP). This is true for teens as well as for adults — taking PrEP as a teenager won’t cause you to have brittle bones when you’re older.

If you have concerns or problems with side effects, it’s important to talk this out with a provider. Since PrEP needs to be taken daily in order for it to work, side effects that make you want to stop taking it should be taken seriously. A doctor or nurse can help you find a way to deal with the side effects and most providers have tips and tricks for dealing with things like nausea and diarrhea. Dealing with side-effects doesn’t necessarily involve taking more medication – you might be advised to try taking PrEP with food or at a certain time of day for example – and it’s important to be open with your provider about any prescription or non-prescription drugs you take in addition to PrEP (including recreational drugs, over the counter medications, supplements, and herbal remedies) since some medications can interact with each other.

PrEP, PEP, and Pregnancy

HIV medications aren’t only used to prevent HIV from sexual transmission — they can also be used to help HIV-positive parents have HIV-negative children. The use of PrEP makes it possible for an HIV-negative person to safely co-create a pregnancy with an HIV-positive person. It is also possible for a person with HIV to carry a pregnancy and give birth without passing on HIV — this involves both the pregnant person being on HIV treatment and the infant taking a 4-6 week course of HIV medication after being born (known as infant PEP). Collectively, the methods used to prevent HIV transmission during conception, pregnancy, childbirth, and breastfeeding are known as prevention-of-mother-to-child-transmission (usually abbreviated as PMTCT) — most organizations have not moved towards more trans inclusive language.

If you’d like to learn more about pregnancy and HIV, you can get the basics from AVERT’s website, written for a global audience. If you have more in-depth questions, the website AIDSmap has just about all the information you could want (but be aware that its info on where to go for treatment is geared towards a UK audience).

What about PEP?

PEP stands for post-exposure prophylaxis. While PrEP is medication that you take to prevent HIV before an exposure happens, PEP is medication that you take to prevent HIV after an exposure happens. If PrEP is like birth control for HIV, PEP is like the morning-after pill.

Unlike PrEP, which is two medications in one pill taken daily, PEP is three medications in two pills that are started within 72 hours after the exposure and taken for 28 days. The sooner PEP is started, the better it works.

Until recently, PEP was usually only offered to healthcare or laboratory workers who were exposed at their jobs (for example, a nurse who got stuck with a needle that was used on a HIV-positive patient) or to people who had been sexually assaulted. Today, many areas offer PEP to folks who have been exposed to HIV through sex, such as folks who experienced a condom breaking or who had condomless sex without planning to. Since PEP is now offered to people outside of on-the-job exposures, you’ll sometimes see the acronym “nPEP,” which stands for non-occupational pre-exposure prophylaxis. PEP gives people an extra option for protecting themselves if a condom slips or breaks, if they take risks they didn’t plan to take, or if they later learn they had sex with someone who is HIV-positive.

The drugs that are used in PEP have changed over the years. Most people who take PEP will take Truvada (the same pill that is used as PrEP) plus one other pill. These modern medications have very few side-effects and are extremely effective (up to 99 percent effective at preventing HIV from sexual exposures, in some studies). Older PEP regimens were only around 70 percent effective, harder to obtain, and had more serious side-effects. These things gave PEP a bad reputation and some people still believe that PEP is hard to access and hard to take.

When should someone use PEP?

PEP is only used for exposures that carry a high risk of HIV transmission. Small or theoretical risks (things that hypothetically could transmit HIV but in reality almost never do) generally don’t warrant getting PEP.

Exposures where it does make sense to get PEP are:

  • You had condomless vaginal or anal sex with someone who is or might be HIV-positive.
  • You were sexually assaulted by someone who is or might be HIV-positive.
  • You shared needles, syringes, or other injection drug supplies with someone who is or might be HIV-positive. It is important to note here that unlike PrEP, which is not currently approved for preventing blood-to-blood transmission of HIV, PEP does work to prevent HIV transmission after a needle stick and is approved for this use. (Why this difference? We haven’t done enough research on using PrEP to prevent blood-to-blood transmission of HIV, so we can’t say for sure that it works in these situations. PEP has been used to prevent blood-to-blood transmission in health workers since the late 1980s so we have plenty of evidence that it works).

Exposures that do not warrant PEP include:

  • Blood, sexual fluids, or other body fluids from an HIV-positive person touched your skin. For example, someone with HIV ejaculated on your body outside of your vagina or anus.
  • You were stuck by an old needle (like a needle on the sidewalk or in the trash). Old dirty needles are not a risk for HIV because HIV cannot survive outside of the human body. However, needle sticks are a risk for tetanus and Hepatitis C, so you should still follow up with a healthcare provider if you’ve been stuck with a dirty needle.
  • You had oral sex — either giving or receiving — with someone who is or might be HIV-positive.
  • You had a type of sex or contact that does not transmit HIV, like manual sex, kissing, hugging, or casual contact like sharing cups or silverware.
  • You had vaginal or anal sex with a condom and the condom did not fall off or break.
  • You had any kind of sex with someone who is HIV-negative.
  • You had any kind of sex with someone who is or might be HIV-positive but you were on PrEP and taking it consistently and correctly.

PEP is highly effective, but it is not a good method of routine HIV prevention. Getting PEP might involve a long wait at the emergency room and the medications can be expensive if you do not have insurance.

If you know you are going to engage in behaviors that can cause HIV infection, or if you often have “slip ups” like forgetting to carry condoms, PEP is not the best prevention strategy for you. Rather than waiting until after an exposure happens, it is easier and more effective to protect yourself before an exposure happens. For this reason, many clinics will offer someone PrEP after they finish taking their course of PEP.

What happens when someone takes PEP?

When you’re prescribed PEP, you will be given an HIV test to make sure you aren’t already HIV-positive and you’ll probably be asked questions about your exposure to assess your risk for HIV. If the healthcare provider decides that you need PEP, you’ll be given a 28 day course of medications. Taking the medication as directed and completing the entire course is extremely important.

When you finish taking your 28 days of medication, you will get another HIV test. Many people who test HIV-negative after taking PEP are asked if they want to start taking PrEP. If you think you might have future HIV scares that require PEP, it’s a good idea to consider starting PrEP. Finally, if you took PEP because of a blood exposure (like sharing supplies for injection drug use), you will also get follow up testing for Hepatitis C.

Where can I get PEP?

PEP is an emergency method of preventing HIV and usually, the way to get PEP is to visit the nearest emergency room (as a walk-in patient — this isn’t something that you need to call an ambulance for).

Emergency rooms are a reliable place to access to PEP and are open 24 hours a day, so if you aren’t sure where to go for PEP, the ER is usually your best bet. Going to the ER isn’t a fun experience and usually involves a long wait (sometimes up to several hours), so it’s a good idea to learn of other places to get PEP in your area. Many sexual and reproductive health clinics, such as Planned Parenthood, now provide PEP, as do some urgent care clinics and student health centers. If you have a primary care provider, they might be able to provide PEP as well (just ask them!).

There are PEP resources listed at the end of this article and it’s not a bad idea to learn what’s in your area. Figuring out where to go in the middle of an HIV scare can be stressful, especially since PEP needs to be started as soon as possible — it makes a lot more sense to be prepared and know where to go before an exposure happens.

Protecting your partners if you are HIV-positive: Treatment as prevention

Most of this article focuses on methods of HIV prevention for people who are HIV-negative but we also want to emphasize that HIV-positive folks can do a ton to protect their partners from HIV.

If you’re living with HIV, getting treatment will not only keep you healthy — it can prevent you from giving HIV to your partners. HIV management is a complicated subject, but the quick and dirty version is that when you take HIV medication (called ART or antiretroviral treatment), the amount of HIV in your blood becomes so low that it cannot be measured by a lab test called a viral load test. This is called being undetectable and folks with HIV usually become undetectable within a few months of starting treatment (getting regular lab tests will let you know when this happens).

There is an overwhelming agreement among HIV providers, advocates, and researchers that people with an undetectable viral load do not transmit HIV to their sex partners — as in there are no known cases of this happening, ever. Even the Centers for Disease Control (who tend to be extra cautious when talking about disease prevention) are on board with this.

This knowledge is a major game changer if you are HIV-positive: you can have a satisfying, healthy sex life without fear of giving HIV to your partners.

So — what does being undetectable actually mean?

The language around having a low HIV viral load (a viral load is a test that measures the amount of HIV in someone’s blood) can get a little confusing and there are a few different terms that get tossed around. Undetectable means the amount of HIV in someone’s blood is too low to show up on a lab test that measures HIV. For most lab tests, this means there are fewer than 20-40 copies of HIV per milliliter of blood (so being undetectable doesn’t mean that someone is HIV-negative or that they’ve been cured — there’s still HIV in the body, just a really small amount). Viral suppression is a little different — it means that the amount of HIV in someone’s blood is low enough to say that the infection is under control and unlikely to cause any health problems. Viral suppression is defined as fewer than 200 copies of HIV per milliliter of blood. Finally, untransmittable means there is not enough HIV in someone’s body for it to spread to other people through sex. People with a viral load lower than 1500 copies per milliliter of blood are not able to spread HIV to others through sex. 1500 is a lot higher than the threshold for being undetectable, so it’s safe to say that folks with an undetectable viral load do not transmit HIV through sex.

The concept of undetectable = untransmittable (U=U) is a major step towards confronting HIV stigma. If you want to learn more about the campaign to spread this knowledge, you can find organizations in your area that are spreading the message.

Putting it all together

A major takeaway from this article is that there are a lot of different ways to prevent HIV and none of them are one-size-fits all. PrEP, PEP, and Treatment as Prevention fit into a larger menu of HIV prevention strategies. Whether you choose to use medications or not, there are a lot of different methods you can use to protect yourself from HIV, like:

  • Getting tested regularly for HIV and STIs and getting any treatment you need.
  • Communicating with your partners about your sexual histories, STI/HIV status, and when you last got tested.
  • Using lube and barriers like condoms, gloves, and dental dams.
  • Limiting your number of sexual partners.
  • Having types of sex that are lower risk for HIV, like manual and oral sex, especially with partners whose status you do not know.
  • Being aware of how things like drugs, alcohol, and social situations impact the types of sexual decisions you make and preparing yourself ahead of time (e.g. carrying condoms when you go out dancing).
  • Knowing how you want to protect yourself before you’re in a sexual situation when things get heated.

You might not be doing everything on the list above, but you’re probably doing (or able to do) a few of these things. Since PrEP does not prevent STIs, it’s a smart idea to combine it with other safer sex strategies. Using PrEP with condoms and lube, for example, protects against STIs and pregnancy while providing some of the most surefire HIV protection you could want.

One of the benefits of using PrEP with respect to STI prevention is that you’ll be getting a complete STI screening every 3 months. Getting diagnosed with an STI is a good sign that your safer sex strategies might need a tune up, and you’ll have a chance to talk to a sexual health provider about how you can better protect yourself. There’s a wealth of info on STI risk, lube and barriers, and getting tested. In the meanwhile, if you’re having a hard time dialing in a prevention strategy that works well for you, Toronto’s Gay Men's Sexual Health Alliance has some advice for reducing your STI and HIV risk, even when your safer sex practices aren’t 100 percent perfect (this information was written with gay cis men in mind, but it applies to folks of all genders and sexualities).

News You Can Use

General information about PrEP

PrEP Facts — General FAQ about PrEP.

Prepster — First person stories from people who have taken PrEP.

Positively Aware — Provides multimedia information about PrEP with an emphasis on resources for women.

Project Inform — Provides general information about PrEP and a ton of information about finding and paying for PrEP in the United States.

AVERT — Provides information on PrEP written for a global audience.

Finding a PrEP Provider

PrEP Watch tracks access to PrEP across the globe. Check out their world map to learn whether PrEP is available in your country and learn more about local PrEP advocacy efforts.

The list below is meant to be as inclusive as possible and includes all regions where PrEP is available. Like most medical resources, access to PrEP is concentrated in wealthy (mostly white) countries in North America, Europe, and Australia and New Zealand. Let’s be real — the reason for this comes down to racism and greed.

PrEP is not available in most of Asia, South America, and Africa except through medical studies. If you live in one of these areas, the PrEP Watch website listed above can help you find out if there are any research projects in your area that provide PrEP for free — but if you want to go this route, make sure it’s a study where you receive a drug that’s proven to be effective.

United States: PrEP in the United States is available through public and private health insurance, for free through certain programs, and with at reduced cost through pharmaceutical companies. The website Please PrEP Me allows you to search for PrEP providers by zipcode or talk to a navigator using instant messaging.

Canada: PrEP in Canada is available for free through the national healthcare system Health Canada. Find a provider at Get PrEPed.

United Kingdom: PrEP in the UK is available for free through the NHS. Find a provider at I Want PrEP Now.

Australia and New Zealand: In Australia, PrEP can be obtained at a reduced cost through the national pharmaceutical benefits program or by enrolling in a PrEP study. Learn more about PrEP studies at Come PrEPd or get the latest updates on PrEP in Australia at Queensland Positive People. PrEP is available for free in New Zealand, learn more at Ending HIV.

Mainland Europe: Options for PrEP vary by country — check them out here at PrEP in Europe.

Resources for PEP

You can learn more about the basics of PEP from the website AVERT or from the San Francisco AIDS Foundation.

PEP is available at emergency rooms. Depending on where you live, you can generally also get PEP from your primary health provider, a university health center, or some local sexual and reproductive health organizations (and in the United States, PEP is available at Planned Parenthood clinics). Going to the ER is a safe bet wherever you live. The Canadian safer sex website The Sex You Want (a project of the Gay Men’s Sexual Health Alliance) has some advice for handling a trip to the ER for PEP that is applicable anywhere.


Finn is an HIV and Hepatitis test counselor at the Berkeley Free Clinic, an all-volunteer collective that provides free medical care to anyone who needs it, no questions asked. Finn is passionate about harm reduction, housing rights, and racial justice in public health. When they're not volunteering at the clinic, Finn can be found biking, rock climbing, and aspiring to go back to school to study medical geography.

More like This