Post-Exposure Prophylaxis (PEP) is a medical treatment designed to prevent Human Immunodeficiency Virus (HIV) infection after a potential exposure. This therapy involves taking medication to stop the virus from establishing a permanent infection in the body. PEP is not a routine prevention method but a time-sensitive option used only in urgent, high-risk situations.
Defining Post-Exposure Prophylaxis
Post-Exposure Prophylaxis is the use of antiretroviral (ARV) drugs by an HIV-negative person immediately following a potential exposure to the virus. The goal of this medication is to interfere with the initial stages of the viral life cycle, specifically by preventing HIV from replicating and spreading through the body’s immune cells. By blocking this process, the medication effectively prevents the virus from taking hold and establishing a chronic infection.
The regimen typically consists of a combination of three antiretroviral (ARV) medications taken daily. This approach is distinct from Pre-Exposure Prophylaxis (PrEP), which is taken before exposure for ongoing prevention. Medical standards divide PEP into two categories based on the nature of the exposure event. Occupational PEP (oPEP) is prescribed for incidents like needlestick injuries in a healthcare setting, while Non-Occupational PEP (nPEP) covers other high-risk events, such as unprotected sexual contact or sharing injection equipment.
Determining Eligibility and the Critical Timeline
A healthcare provider must conduct a risk assessment to determine eligibility for PEP, considering the type of exposure and the HIV status of the source. High-risk exposures involve contact with infectious body fluids—such as blood, semen, vaginal secretions, or rectal fluids—through non-intact skin, mucous membranes, or a puncture injury. If the source is known to be living with HIV and has a detectable or unknown viral load, the risk of transmission is substantial, making PEP necessary.
The effectiveness of PEP is directly tied to how quickly treatment begins. PEP must be initiated within 72 hours (three days) of the potential exposure. Starting the medication as soon as possible, ideally within the first 24 hours, provides the greatest chance of success. Starting the regimen after the 72-hour mark is not recommended because the virus is generally considered to have already established infection, significantly reducing the treatment’s ability to prevent seroconversion.
The Administration and Duration of PEP Treatment
Once PEP is determined to be appropriate, the first dose must be taken immediately, often administered in the clinic or emergency room. Before starting, baseline testing is required to confirm the exposed person’s HIV-negative status and check for other conditions. This initial testing typically includes an HIV test, screening for Hepatitis B and C, and blood tests to check kidney and liver function. If the initial HIV test is positive, PEP is not needed, and care shifts to treating established HIV infection.
The standard treatment course for PEP is 28 consecutive days of daily medication. This consistent dosing ensures the antiretroviral drugs remain at effective levels long enough to suppress any initial viral replication. Due to the urgent nature of the intervention, PEP medications are usually prescribed at sites like emergency departments, urgent care clinics, or specialized sexual health clinics. A follow-up plan monitors for side effects and includes repeat HIV testing at the conclusion of the 28-day course and again several weeks later.
Managing Side Effects and Ensuring Adherence
Modern PEP regimens are generally well-tolerated, but some individuals experience temporary side effects as their body adjusts to the medication. Common mild side effects include digestive issues like nausea, vomiting, or diarrhea, fatigue, or headache. Healthcare providers often recommend supportive care, such as anti-nausea medications, to manage these issues. These discomforts are usually manageable and subside as the body adjusts to the drugs.
Adherence to the daily medication schedule is essential. Stopping the course early or missing doses compromises drug levels, which can allow the virus to overcome the treatment and establish a permanent infection. If side effects become severe or unmanageable, the patient should contact their healthcare provider immediately. The provider may be able to adjust the regimen or prescribe alternative medications, ensuring the full four-week course is completed without interruption.