Nursing care
HIV Prevention and PrEP, explained for the bedside and the exam
Written and reviewed by Dana Whitfield, RN, MSN · 4 min read · Updated September 2026
Short answer
Pre-exposure prophylaxis, or PrEP, is a daily oral medication, most commonly tenofovir-emtricitabine, taken by an HIV-negative person at ongoing risk of exposure to prevent infection. It requires an HIV test every three months and periodic kidney function monitoring, since tenofovir is renally cleared. It does not treat existing HIV infection and must never be started without a confirmed negative HIV test first.
The idea in one paragraph
PrEP is prevention, not treatment. It is prescribed to someone who does not have HIV but has an ongoing risk of exposure — a serodiscordant partner, inconsistent condom use, injection drug use with shared equipment, or a recent sexually transmitted infection. Daily tenofovir-emtricitabine, taken consistently, reduces the risk of acquiring HIV through sex by around 99% and through injection drug use by over 70% when adherence is high.
The medication works by blocking HIV from establishing infection in cells exposed to the virus. It is not a vaccine and confers no protection once stopped, which is why adherence and ongoing risk assessment matter more than the prescription itself.
Why it matters clinically
Starting PrEP on someone who already has undiagnosed HIV is a serious clinical error. Tenofovir-emtricitabine alone is not enough to suppress an existing infection, and using it as if it were full treatment risks the development of drug-resistant HIV. This is why a negative HIV test is mandatory immediately before the first prescription, not assumed from history.
Renal function is the other clinical thread running through PrEP care. Tenofovir is cleared by the kidneys, and PrEP is generally avoided or dose-adjusted in patients with significantly reduced kidney function. Baseline renal function is checked before starting, and monitored periodically thereafter, alongside the routine three-month HIV testing that catches any breakthrough infection early and prevents the drug being continued as an unwitting single-agent treatment for undiagnosed HIV.
How to apply it at the bedside
Confirm a negative HIV test before any PrEP prescription is initiated or renewed, and reinforce that this test happens again every three months for the duration of therapy. This interval is not arbitrary — it is short enough to catch a new infection before resistance develops from continued single-regimen exposure.
Assess and document baseline renal function before starting, and screen for other sexually transmitted infections and hepatitis B status at the same visit, since tenofovir-emtricitabine also has activity against hepatitis B and stopping it abruptly in a co-infected patient can cause a hepatitis flare. Counsel on daily adherence: PrEP's effectiveness depends heavily on consistent dosing, and missed doses create gaps in protection. Reassess risk factors at each visit rather than treating the prescription as a one-time decision.
Where students get it wrong
A frequent mistake is confusing PrEP with PEP, post-exposure prophylaxis. PrEP is a daily, ongoing regimen for someone at continuous risk, taken before any single exposure. PEP is a short emergency course started within 72 hours after a specific known or suspected exposure. They use overlapping but not identical drug regimens and completely different timing logic.
The second common error is treating the HIV test as a one-time gatekeeper rather than an ongoing requirement. Students sometimes answer that a baseline negative test is sufficient for the duration of therapy, missing that testing repeats every three months. Also watch for skipping the renal function angle entirely — it is easy to focus on the HIV prevention mechanism and forget that tenofovir is nephrotoxic in vulnerable kidneys.
Worked examples
A patient in a serodiscordant relationship asks to start PrEP and reports no recent HIV test. The correct nursing action is to obtain a current HIV test and confirm it is negative before the prescription is initiated, not to proceed based on the patient's self-report of status.
A patient on PrEP for eight months reports occasional missed doses and asks if quarterly testing is still necessary. The correct response affirms that HIV testing every three months continues throughout therapy regardless of adherence pattern, because inconsistent dosing raises the risk of a breakthrough infection going undetected.
How the exam tests it
NCLEX items often test the PrEP-versus-PEP distinction by describing a specific exposure scenario, such as a needlestick or unprotected contact with a known-positive partner, and asking which prophylaxis regimen applies and within what timeframe. Recognizing the 72-hour PEP window versus the ongoing daily PrEP regimen is the key discrimination point.
Other questions present a lab value, such as a rising creatinine or declining eGFR, in a patient on PrEP and ask for the appropriate nursing action, testing whether you connect tenofovir to renal monitoring. Expect distractors that ignore the kidney finding or that suggest discontinuing without further evaluation, when the correct action is reporting the finding for reassessment of the regimen.
The next step on this is the same as on everything else here: answer questions and read the rationales. Our health promotion practice questions are the closest set to what this page covers.
One question from the health promotion set
A client at 30 weeks' gestation reports a headache that will not resolve, blurred vision, and swelling of the hands. Blood pressure is 158/104 mm Hg. Which action should the nurse take first?
Rationale
Headache that will not resolve, visual changes, and a blood pressure of 158/104 after 20 weeks are severe features of preeclampsia — the client is at risk of seizing. Notify and prepare for magnesium sulfate, which is given for seizure prophylaxis rather than for the blood pressure itself. Resting and rechecking in an hour delays treatment, and a urine culture answers a different question entirely.
Answer: B
Common questions
What medication is used for PrEP?
The most commonly prescribed regimen is daily oral tenofovir-emtricitabine. Other formulations exist, but this combination remains the standard first-line choice for most patients at risk of HIV exposure.
How often does someone on PrEP need an HIV test?
Every three months for as long as they remain on the medication. This catches any breakthrough infection early, before continued use of the drug alone could allow drug-resistant HIV to develop.
Can PrEP be started without checking kidney function?
No. Tenofovir is cleared renally, so baseline kidney function is checked before starting and monitored periodically during treatment, since PrEP is generally avoided or adjusted in patients with significant renal impairment.
Is PrEP the same as PEP?
No. PrEP is a daily ongoing regimen for someone with continuous risk of exposure. PEP is a short emergency course started within 72 hours of a specific exposure event and is not meant for long-term use.