PrEP (Pre-Exposure Prophylaxis) is medicine people at risk for HIV take to prevent getting HIV from sex or injection drug use. It is a way for people who do not have HIV but who are at very high risk of getting HIV to prevent HIV infection by taking a pill every day. The pill (brand name Truvada) contains two medicines (tenofovir and emtricitabine) that are used in combination with other medicines to treat HIV. When someone is exposed to HIV through sex or injection drug use, these medicines can work to keep the virus from establishing a permanent infection.
When taken daily, PrEP is highly effective for preventing HIV. Studies have shown that PrEP reduces the risk of getting HIV from sex by about 99% when taken daily. Among people who inject drugs, PrEP reduces the risk of getting HIV by at least 74% when taken daily. PrEP is much less effective if it is not taken consistently. As PrEP only protects against HIV, condoms are important for the protection against other STDs. Condoms are also an important prevention strategy if PrEP is not taken consistently.
In the article
- Key points about PrEP
- How often should you take the PrEP medication?
- Can you switch between daily PrEP and on-demand PrEP?
- How often are medical appointments for PrEP made?
- How long does PrEP take to protect a person from HIV exposure?
- How well does PrEP work?
- Is PrEP effective for treating HIV infection?
- How would you know if PrEP is right for you?
- Would PrEP still work to prevent HIV if you don't use condoms?
- Do you need PrEP when your sex partner has HIV and an undetectable viral load because they are on HIV treatment?
- What are the side effects of the PrEP medications?
- Would you have to take PrEP for the rest of your life? What if you want to stop?
- Is it safe to take PrEP, when you drink alcohol and/or use recreational drugs?
- Can taking PrEP lead to developing drug resistant HIV if you become infected?
Key points about PrEP
There are two approved medications as PrEP for HIV: Truvada (tenofovir disoproxil fumarate 300 mg/emtricitabine 200 mg), and Descovy (tenofovir alafenamide 25 mg/emtricitabine 200 mg). Descovy is not approved for use by cis-gender women. Here are some key points to note about PrEP.
- PrEP medication is prescribed by a healthcare provider. People interested in PrEP can work with a healthcare provider to determine how PrEP can be tailored to their individual needs and circumstances
- PrEP is only for people who are not living with HIV. HIV testing should be conducted before starting PrEP and repeated every three months to make sure the person is not living with HIV. Testing may be done by the healthcare provider or at a conveniently located community-based organization (CBO), healthcare facility or lab
- Some people benefit from counseling and support for taking the medication regularly. If this is needed, the person can talk with the healthcare provider, a trusted CBO, a peer worker, or other provider
- People at risk for HIV are also at risk for sexually transmitted infections (STIs). Counseling about using condoms to prevent STIs and periodic screening for STIs is important and may be provided by the healthcare provider, a trusted CBO, or other provider
How often should you take the PrEP medication?
You and your healthcare provider can work together to decide the best way for you to use PrEP. There are two different ways that people take PrEP:
1. Daily PrEP
Daily PrEP involves people of any gender identity (cis-gender man, cis-gender woman or transgender man or woman) taking 1 pill once a day, every day. With daily PrEP, a person can feel protected from HIV whenever they have sex or inject substances. It is for people who have possible exposure to HIV on a frequent basis, or an unpredictable basis. An important benefit of daily PrEP is that the person is always protected and can establish a daily habit of taking the medication. Daily PrEP with Truvada is the only method proven to be effective for cis-gender women and transgender men who have vaginal intercourse.
2. On-Demand PrEP
On-demand PrEP is only for cis-gender men who have sex with men (MSM). On-demand PrEP involves taking 2 pills, 2-24 hours before a possible sexual exposure to HIV and then continuing to take 1 pill each day until 2 days after their last possible sexual exposure. The only PrEP medication approved for on-demand use is Truvada. If a cis-gender MSM has a single possible exposure, they would take 2 pills, 2-24 hours before having sex and then would take 1 pill each day for 2 additional days.
If a person had several possible exposures over the course of 2 or more days, the person would take 2 pills, 2-24 hours before the possible exposure, then 1 pill for each day they are having sex, and then 1 pill each day for 2 days after the last possible exposure. On-demand PrEP is for cis-gender MSM who have occasional risk for HIV that can be predicted at least 2 hours in advance. Cis-gender women, cis-gender men who have sex with women, people of trans experience, and people who share injection equipment should choose daily PrEP, not on-demand PrEP.
Can you switch between daily PrEP and on-demand PrEP?
It is important to talk with your healthcare provider about whether daily PrEP or on-demand PrEP is right for you. On-demand PrEP is only for cis-gender MSM. Other individuals are not eligible for on-demand PrEP because studies have not demonstrated that it is effective for other populations. Before switching from daily PrEP to on-demand PrEP, or vice versa, a cis-gender MSM should consult with their healthcare provider.
How often are medical appointments for PrEP made?
People who want to take PrEP to prevent HIV can work with their healthcare provider to determine the schedule of medical appointments that best meets their needs. Here is a general description of the schedule of medical appointments for PrEP.
- Initial Medical Appointment: This first appointment includes education about PrEP, a discussion about readiness to take PrEP, a review of daily versus on-demand PrEP, HIV testing, and other lab work. If the person is ready to start PrEP, the medication can be started right after the initial medical appointment
- First Follow-Up Contact: The healthcare provider and person should make a plan for a follow-up appointment or call at a convenient time, usually within 2-4 weeks, to:
- Check in on how things are going, including side effects
- Troubleshoot any problems with payment or access to support services
- HIV testing: The person should have an HIV test every three months to make sure they have not acquired HIV. The healthcare provider can order the testing which can be done at their office, a conveniently located CBO, health facility or lab. It is important that the results of the test are provided to the healthcare provider who prescribed PrEP
- Follow-Up Appointments and Prescription Refills: The frequency of follow-up appointment is established jointly by the healthcare provider and the person
How long does PrEP take to protect a person from HIV exposure?
The PrEP medication must reach and maintain a certain level in the blood and the body’s mucus membranes to provide protection. The amount of time it takes may vary from person to person. For people taking daily PrEP who engage in anal intercourse, the medication must be taken each day for 7 days to reach the level needed for full protection. Cis-gender MSM who are taking on-demand PrEP, must take two pills, 2-24 hours before having sex.
For the receptive partner in vaginal intercourse, it takes approximately 20 days of taking the medication consistently to reach the level of full protection in the female genital tract. This is why cis-gender women and transgender men who have receptive vaginal intercourse should not take on-demand PrEP. People of transgender experience should talk with their healthcare provider about their specific sexual practices to best determine the length of time it will take to be fully protected.
How well does PrEP work?
The PrEP medication works very well at preventing a person from getting HIV. Everyone taking PrEP should be sure to take the medication as agreed upon with the healthcare provider, but it is especially important for cis-gender women and transgender men who engage in vaginal intercourse to take it consistently each day to be fully protected during receptive vaginal intercourse. The more days a person misses a dose, the less protective the medication will be for any exposures that occur during that time period.
Is PrEP effective for treating HIV infection?
PrEP medications are not effective alone for treating HIV infection. If you acquire HIV infection while taking PrEP, the provider who conducted the HIV test should either provide HIV medical care or refer you to a healthcare provider who can provide HIV care. The HIV care provider will conduct lab tests and determine the most effective regimen to treat your HIV infection. There is no evidence that having taken PrEP will impact the effectiveness of your HIV treatment. People who acquire HIV while on PrEP can be successfully treated with HIV medications.
How would you know if PrEP is right for you?
PrEP is one of many options for preventing HIV. HIV is passed from one person to another through sharing injection drug equipment or through anal or vaginal sexual intercourse. People can avoid getting HIV by:
- Not sharing drug injection equipment (needle, syringe, cooker, cotton, etc.)
- Avoiding anal or vaginal intercourse
- Having only one monogamous sex partner whose HIV status is known to be negative
- Having only one partner who is living with HIV and has an undetectable viral load
It is important to be aware that a person living with HIV who is on HIV treatment and is virally suppressed for six months or longer cannot pass HIV to a partner through sex. If you have sex with more than one partner, taking PrEP or consistent and correct use of condoms each time you have sex, can prevent you from getting HIV. The healthcare providers should discuss PrEP as an HIV/STD prevention option for adults or adolescents who:
- Have unprotected anal or vaginal intercourse with:
- A partner whose HIV status is unknown
- A partner who is living with HIV but not on HIV treatment
- A partner who is living with HIV but not does not have an undetectable viral load
- Have unprotected anal or vaginal intercourse with a partner who is living with HIV, on treatment and virally suppressed but wishes to be on PrEP for additional protection
- Are attempting to conceive with a partner who is living with HIV
- Have multiple or anonymous sex partners or, have partners who have multiple or anonymous sex partners
- Participate in sex parties or have partners who do this
- Are involved in transactional sex, such as sex for money, drugs, or housing, including commercial sex workers and their clients, or have partners who do this
- Have been diagnosed with at least one STI in the previous 12 months
- Use of mood-altering substances during sex, such as alcohol, methamphetamine, cocaine, and ecstasy
- Inject substances, or have partners who inject substances, including illicit drugs and hormones
- Are receiving post-exposure prophylaxis (PEP) and have ongoing high-risk behavior or have used multiple courses of PEP
- Request the protection of PrEP even if their sex partners have an undetectable HIV viral load
- Self-identify as being at risk without disclosing specific risk behaviors
- Acknowledge the possibility of, or anticipates risk behaviors in the near future
It is important to weigh the pros and cons and have an open and honest conversation about PrEP with your healthcare provider before beginning PrEP. PrEP is always voluntary and only you can determine if PrEP is right for you.
Would PrEP still work to prevent HIV if you don't use condoms?
If a person takes the PrEP medication consistently as directed, it provides a high level of protection against HIV. Condoms provide protection against sexually transmitted infections (STIs). People who are on the PrEP medication but are not using condoms may be exposed to an STI. It is important to be aware that having an STI can increase a person’s chance of getting HIV if exposed to the virus. Some STIs don’t have symptoms or symptoms may disappear on their own for periods of time.
If you are not using condoms regularly, it would be especially important to have regular testing for STIs and to get treated as soon as possible if you have an STI. Screening for chlamydia and gonorrhea should include swabs of a person’s genitals, rectum and mouth. Learning about the signs and symptoms of STIs is helpful in identifying whether you or one of your partners has an STI. Condom use is recommended but choosing to not use condoms routinely should not prevent you from being prescribed PrEP.
Individuals living with HIV who are taking HIV treatment consistently and have an undetectable viral load for at least 6 months cannot transmit the virus to an HIV-negative partner through sexual activity. In sero-discordant or magnetic couples (one person is living with HIV and the other not living with HIV), PrEP may be used by the HIV-negative partner for additional protection.
What are the side effects of the PrEP medications?
Truvada and Descovy are both recognized as well-tolerated medications with few side effects. In clinical trials, only a small number of people found the side effects serious enough to stop taking the medication. People taking PrEP should discuss any side effects they experience with their healthcare provider. In many cases, side effects are only short term and can be managed. Two important health issues related to taking PrEP include kidney function and bone density.
Your healthcare provider will ask if you have a history of kidney disease and will periodically order lab work to monitor your kidney function. Bone density will be monitored as needed. Scientific evidence shows that when taken as directed, Truvada is safe and effective. Since there are risks to taking any medication, individuals should speak with their healthcare provider about the benefits, risks (side effects), and possible alternatives for every medication they choose to take in order to understand the best choices for their specific situation.
Would you have to take PrEP for the rest of your life? What if you want to stop?
PrEP is not intended to be a life-long program. Rather, it is a program where the healthcare provider works with you to develop an individualized plan with as many renewals of the prescription as you and the healthcare provider agree to. For many people, life circumstances change over time and the risk for HIV may be reduced or eliminated. You should discuss the issue of how long you want to take the PrEP medication with your provider.
If for any reason you want to stop taking the PrEP medication, consult with the healthcare provider who prescribed it, or another provider who is familiar with PrEP. Generally speaking, cis-gender men taking on-demand PrEP should continue taking the PrEP medication for at least 2 days after any possible exposure. Anyone taking daily PrEP should continue taking the medication for 28 days after the last possible exposure.
Is it safe to take PrEP, when you drink alcohol and/or use recreational drugs?
Alcohol and recreational drugs are not known to interact with PrEP medications. It is safe to take PrEP before, after and on days when you are “partying”. In fact, it is important to take extra steps to make sure you take PrEP according to the healthcare provider’s directions when you are “partying”.
Can taking PrEP lead to developing drug resistant HIV if you become infected?
HIV testing is a critical component when using PrEP for HIV prevention. HIV testing is done before a person begins PrEP to ensure that only HIV negative people are prescribed PrEP. Periodic HIV testing for everyone taking PrEP ensures that anyone who gets HIV will be identified quickly so they can be put on an effective treatment regimen. If a person on PrEP gets HIV, drug resistance testing is done to determine an effective treatment regimen. There is no evidence that PrEP can lead to higher rates of drug resistant virus in a person.