Medication That Can Prevent HIV Infection

Medication that prevents HIV infection.

STDAware presents a guide to PrEP and PEP

Modern medicine has come a long way in finding ways to reduce the risk of HIV infection as well as manage an active HIV infection so that it does not turn into AIDS.

When it comes to preventing HIV, there are currently two medically proven approaches to reducing HIV infection risk (when taken correctly and consistently). These treatments are PrEP and PEP.

Neither PrEP or PEP can cure HIV. Both PrEP and PEP are preventative measures to assist in ensuring that HIV does not take hold in the body and are specific to certain types of risk.

Once HIV invades the body it cannot be cured. However, there are many effective treatments that can allow an HIV infected individual to continue living a long and fulfilling life. To read more about HIV and treatment options, click here.


About PrEP

PrEP stands for “pre-exposure prophylaxis” and is the antiretroviral (ART) medication regime prescribed to HIV-negative individuals before they come into contact with HIV. PrEP is designed to protect individuals who are at high risk of contracting HIV. Candidates for PrEP fall into two categories:

  • oPrEP (Occupational pre-exposure prophylaxis) for individuals at risk of being exposed to HIV through occupational requirements and conditions such a healthcare worker or official that could be exposed to needlesticks or other biohazards.
  • nPrEP (Non-occupational pre-exposure prophylaxis) for individuals at risk of HIV exposure through sexual activity, orientation, intravenous drug use, demographics, and other social and behavioral factors.

The PrEP protocol is not a vaccine.  PrEP is a daily administration of an oral medication named Truvada®. Truvada is a combination of two drugs commonly used to treat active HIV infections. They are tenofovir and emtricitabine.

PrEP must be taken for a minimum of seven days to become effective during receptive anal sex and a minimum of 20 days to be effective during receptive vaginal sex or the sharing of needles. The time period for effectiveness during insertive anal and vaginal sex is not yet conclusive (CDC, 2018).

PrEP can be 92-99% effective in reducing the risk of HIV infection from sexual contact (NEJM, 2010) and more than 70% effective in reducing HIV infection from needle sharing (when taken correctly) (CDC, 2018).  

Correct and consistent use of PrEP medication is referred to as adherence. Strict adherence to the daily PrEP protocol is crucial to ensuring sufficient levels of medicine exist in the body so that it can fight off any potential HIV exposure and subsequent infection.

In order for a doctor to prescribe PrEP a definitive HIV negative, RNA test result must be provided. An RNA HIV test will detect whether or not there is the presence of the HIV in the blood. Click here to learn more about the RNA HIV test offered by

Ongoing testing for HIV should be performed every 3-6 months to ensure that an individual on PrEP has not become infected with HIV. Taking PrEP while infected with HIV can result in drug resistance. Drug resistance means that the drugs used to treat a condition will be less effective, or not effective at all. 

STDAware offers no-cost post-test consultation with a medical professional for anyone who tests positive for HIV.

While PrEP may be effective in reducing the risk of contracting HIV from an infected partner, the use of condoms in tandem with PrEP is highly recommended because PrEP does not offer any protection against other STDs. Careful and responsible sexual activity is advised for anyone on PrEP. 

PrEP has been found to be effective in consenting serodiscordant relationships (meaning the couple is aware that one partner is HIV positive and the other is not). And it has been approved for use during conception, pregnancy, and breastfeeding. However, some risks associated with long-term use have not yet been determined.

The most common side effects of taking PrEP are upset stomach, nausea, headache, and unexpected weight loss. Less common but more serious side effects could be reduced kidney function and failure, a lactic acid build-up in the body, decrease liver function and failure, bone density problems. Clinical studies showed that kidney function and bone density returned to normal levels once a patient stopped PrEP (NEJM, 2010). 

The cost of PrEP is covered by most insurance plans and Medicare. There are also many medication assistance and social service options available to help cover the cost of PrEP.

Starting a PrEP regime involves more than taking a pill once a day. The challenge of taking prescription medication on a daily basis, at the same time comes with its own set of challenges. In addition to daily administration of oral medication, patients who would like to start PrEP need to understand that PrEP includes regulated and regular doctor’s visits and exams to monitor kidney and liver functions and well as running routine HIV tests to ensure an infection has not occurred.

PrEP does not have to be taken forever. Should a patient decide to stop using PrEP they should take measures to ensure they do so under a medical professionals supervision. 

PrEP vs. PEP

About PEP

PEP stands for “post-exposure prophylaxis,” and is the (ART) medication routine prescribed for individuals who have been exposed to HIV through sexual or needle sharing activity. There are two categories of PEP candidates. They are oPEP and nPEP. 

  • oPrEP (Occupational post-exposure prophylaxis) for individuals who have been exposed to HIV through occupational requirements and conditions such a healthcare worker or official that is exposed to needlestick injury or other biohazards.
  • nPrEP (Non-occupational post-exposure prophylaxis) for individuals who have been exposed to HIV through sexual activity, orientation, intravenous drug use, demographics, and other social and behavioral factors.

PEP is not a vaccine but it an orally administered medication for HIV negative individuals who have reason to believe they have been exposed to HIV. Similar to PrEP, PEP includes the use of named Truvada®, but it also includes the addition of an additional ART called Isentress® (raltegravir). 

PEP must be taken within 72 hours of exposure in order to be effective.  It is best if PEP can be initiated within 24 hours of suspected exposure and the earlier PEP can be started the more successful it is at preventing and HIV infection. Use of PEP must be continued and monitored for 28 days.

PEP is NOT a replacement for condoms or other safe sex measures, and it should only be used as an emergency response to an HIV exposure because of one of the following conditions:

  • Suspected exposure to HIV during sexual activity (e.g., broken condom)
  • Suspected exposure to HIV through need sharing activity (e.g., intravenous drug use)
  • Suspected exposure to HIV through workplace hazards (e.g., medical aid suffering a needle stick injury or exposure to other biohazardous materials)
  • Suspected or unknown exposure due to rape

In any of the instances or similar instances to the above, the individuals should take immediate measures to see a medical professional either through the emergency room or urgent care facilities.

While PEP is highly effective at preventing HIV infections from taking hold in the human body, it is not 100% effective, and therefore the continued use of condoms and other safe sex practices is highly recommended to ensure any potential HIV infection is not spread to additional sexual or needle-sharing partner(s). PEP does not provide any protection against other STDs.

The CDC offers a comprehensive tool on how to reduce your HIV exposure risks.  

Like PrEP, PEP must be taken, orally, daily (sometimes twice daily). Strict adherence to PEP protocol is critical to the success of the treatment and also requires careful monitoring through frequent medical professional follow up visits and laboratory testing to monitor the function of the kidneys, liver, and to check for possible active HIV infection.

The most common side effects of PEP included trouble sleeping, headaches, nausea, dizziness, upset stomach, and fatigue. Less common but more serious side effects could include allergic (sometimes life-threatening) reaction or skin reactions, reduction in liver function or liver failure, reduction of kidney function or kidney failure, vomiting, suicidal thoughts, and weakness. According to the Isentress® website (2018): “Changes in your immune system (Immune Reconstitution Syndrome) can happen when you start taking HIV-1 medicines. Your immune system may get stronger and begin to fight infections that have been hidden in your body for a long time. Tell your doctor right away if you start having new symptoms after starting [Isentress]” This type of immune response could result in latent herpes or hepatitis infection being activated in the body. 

If HIV exposure occurs while pregnant or nursing, a medical professional should perform a careful assessment before starting PEP. Some adjustments may need to be made in the PEP protocol to protect the fetus.  It is advised that breastfeeding mothers who are exposed to HIV avoid breastfeeding for at least three months after exposure and treatment before resuming nursing in order to reduce the risk of passing HIV to the infant through breast milk and to ensure that the levels of toxicity in breast milk are reduced to safe levels (Medscape, 2018). 

PEP is covered by most insurance plans and Medicare. If insurance or Medicare will not cover PEP, urgent applications can be submitted to many Patient Assistance Programs (PAPS), which are run through the manufacturers and can avoid delay in starting PEP.

If PEP is prescribed in response to a sexual assault, partial or full reimbursement for PEP medication and clinical costs can be sought through the Office for Victims of Crime (funded by the U.S. Department of Justice).

Once PEP is concluded, patients should continue to exercise precautions to avoid HIV infection. The CDC and medical experts urge that any sexually active individual, who is not in a long-term, mutually monogamous relationship, is routinely tested for STDs anytime there is a change in sexual partners or habits.

Routine screening is an effective defense against STD infection. STDAware offers full panel and individual testing options.

Resource List

  • Secretary’s Minority AIDS Initiative Fund (SMAIF) –
  • U.S. Department of Health and Human Resources ––pep-
  • San Francisco AIDS foundation –
  • U.S. Centers for Disease Control and Prevention –
  • New England Journal of Medicine –
  • Medscape:
  • Merck & Co., Inc., 2018 –

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