Post-exposure prophylaxis (PEP) involves taking anti-HIV medications immediately after any potential exposure to HIV (human immunodeficiency virus) to prevent HIV infection (acquired immune deficiency syndrome or AIDS). PEP may prevent HIV from entering the cells in the body and stop someone from getting an HIV infection. However, there is no guarantee that a person exposed to HIV will not become infected with HIV after taking PEP. PEP should be used only in emergencies after exposure to HIV. It should not be used as a replacement for or HIV prevention methods.
PEP normally consists of three anti-HIV drugs from the different drug classes. The most recent guidelines recommend using Truvada (a fixed-dose combination tablet combining emtricitabine and tenofovir) and Isentress (raltegravir) from the integrase inhibitor class.
Effectiveness of PEP
The important things that need to be followed for PEP to work effectively include:
- PEP must be started within 72 hours of possible exposure to HIV for it to be effective.
- It works best if PEP is taken within 24 hours of being exposed to HIV.
- Medication must be taken as advised, regularly every day for 28 days (4 weeks course).
- Drug levels must remain high during the month of treatment to help prevent infection. (Irregular medication will lower the drug levels in the body.)
The PEP treatment will not be effective if:
- The medicines are taken irregularly or incorrectly.
- The medicines are not taken soon enough, which is within 72 hours after potential exposure to the virus.
- The full course of PEP drugs is not completed.
- Further exposures to HIV happen while taking PEP.
What is the role of PEP in the prevention of HIV?
Once HIV enters the body, they infect certain immune cells and replicate within these immune cells. Then, it spreads throughout the body causing HIV infection. PEP works by interfering with this pathway that HIV uses to cause infection in the body. The anti-HIV drugs get into the bloodstream and tissues. This prevents HIV from replicating within the body’s immune cells.
The medicines used in PEP are called antiretroviral medications (ART). These include tenofovir, emtricitabine (these two drugs come in one pill), and a third drug either raltegravir or dolutegravir. These medications prevent HIV from making copies of itself and spreading through the body.
PEP involves using the combination of the three HIV medications, which are taken two to three times a day for 28 days, to reduce the risk of getting HIV infection after a potential exposure to HIV. PEP is effective in preventing HIV infection when it’s taken correctly, but it’s not 100% effective. PEP can lower the risk of getting HIV infection by more than 80%.
When is PEP necessary?
PEP must be taken by a person soon after a known or doubted exposure to HIV to prevent HIV transmission.
Incidences of known or doubted exposure to HIV includes:
- Unprotected sex (without using a condom) with someone whose HIV status is not known or who is HIV-positive.
- Condom breaking during sex.
- Sexual assault.
- Drug users, sharing needles or other injecting equipment with someone who may have HIV.
- Occupational PEP: After exposure to HIV material at work (health care).
- Getting blood or other body fluids that may have HIV in the eyes, mouth, or on the skin.
- A child born to an HIV-positive mother.
What are the side effects of PEP?
PEP is safe. The side effects caused are not life-threatening and can be treated. PEP may cause the following side effects in some people:
HIV.gov. Post-Exposure Prophylaxis. U.S. Department of Health & Human Services. https://www.hiv.gov/hiv-basics/hiv-prevention/using-hiv-medication-to-reduce-risk/post-exposure-prophylaxis
Markelz AE. Postexposure HIV Prophylaxis in Physicians and Medical Personnel. Medscape. https://emedicine.medscape.com/article/1991375-overview
Top How Effective Is PEP? Related Articles
Common Medical Abbreviations & Terms
Doctors, pharmacists, and other health-care professionals use abbreviations, acronyms, and other terminology for instructions and information in regard to a patient's health condition, prescription drugs they are to take, or medical procedures that have been ordered. There is no approved this list of common medical abbreviations, acronyms, and terminology used by doctors and other health- care professionals. You can use this list of medical abbreviations and acronyms written by our doctors the next time you can't understand what is on your prescription package, blood test results, or medical procedure orders. Examples include:
- ANED: Alive no evidence of disease. The patient arrived in the ER alive with no evidence of disease.
- ARF: Acute renal (kidney) failure
- cap: Capsule.
- CPAP: Continuous positive airway pressure. A treatment for sleep apnea.
- DJD: Degenerative joint disease. Another term for osteoarthritis.
- DM: Diabetes mellitus. Type 1 and type 2 diabetes
- HA: Headache
- IBD: Inflammatory bowel disease. A name for two disorders of the gastrointestinal (BI) tract, Crohn's disease and ulcerative colitis
- JT: Joint
- N/V: Nausea or vomiting.
- p.o.: By mouth. From the Latin terminology per os.
- q.i.d.: Four times daily. As in taking a medicine four times daily.
- RA: Rheumatoid arthritis
- SOB: Shortness of breath.
- T: Temperature. Temperature is recorded as part of the physical examination. It is one of the "vital signs."
HIV/AIDS MythsWhat is HIV versus AIDS? What are the symptoms of HIV? Is there an HIV cure? Discover myths and facts about living with HIV/AIDS. Learn about HIV and AIDS treatment options, symptoms, and diagnosis.
HIV vs. AIDSHuman immunodeficiency virus causes HIV infection. Acquired immunodeficiency syndrome (AIDS) is a condition that results after HIV has extensively damaged a person's immune system. Risk factors for HIV and AIDS include use of contaminated needles or syringes, unprotected sex, STDs, receiving a blood transfusion prior to 1985 in the United States, having many sex partners, and transmission from a mother to her child.
HIV/AIDS QuizNow, more than ever, you should know about HIV/AIDS, especially its causes, symptoms treatments, and complications. Take the HIV/AIDS Quiz now!
Human Immunodeficiency Virus (HIV)HIV (human immunodeficiency virus) infection left untreated causes AIDS (acquired immunodeficiency syndrome). The human immunodeficiency virus (HIV) is a type of virus called a retrovirus, which can infect humans when it comes in contact with tissues that line the vagina, anal area, mouth, or eyes, or through a break in the skin. HIV infection is generally a slowly progressive disease in which the virus is present throughout the body at all stages of the disease. Three stages of HIV infection have been described. The initial stage of infection (primary infection), which occurs within weeks of acquiring the virus, often is characterized by the flu- or mono-like illness that generally resolves within weeks. The stage of chronic asymptomatic infection (meaning a long duration of infection without symptoms) lasts an average of eight to 10 years without treatment. The stage of symptomatic infection, in which the body's immune (or defense) system has been suppressed and complications have developed, is called the acquired immunodeficiency syndrome (AIDS). The symptoms are caused by the complications of AIDS, which include one or more unusual infections or cancers, severe loss of weight, and intellectual deterioration (called dementia). When HIV grows (that is, by reproducing itself), it acquires the ability to change (mutate) its own structure. These mutations enable the virus to become resistant to previously effective drug therapy. The goals of drug therapy are to prevent damage to the immune system by the HIV virus and to halt or delay the progress of the infection to symptomatic disease. Therapy for HIV includes combinations of drugs that decrease the growth of the virus to such an extent that the treatment prevents or markedly delays the development of viral resistance to the drugs. The best combination of drugs for HIV are those that effectively suppress viral replication in the blood and also are well tolerated and simple to take so that people can take the medications consistently without missing doses.
Is HIV PEP (Post-Exposure Prophylaxis) Recommended for Me?Post-exposure prophylaxis (PEP) refers to a short course of antiretroviral medications taken soon after a possible exposure to HIV to prevent the virus from infecting your body.
Should I Take PrEP for HIV?Pre-exposure prophylaxis (PrEP) is a course of prescribed medications that people who are at risk of human immunodeficiency virus (HIV) may take to prevent infection. This medication is administered to individuals who have tested negative for HIV but are at a high risk of HIV infection.