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PEP is a 28-day course of HIV medicines after a possible exposure. Seek urgent assessment now: when indicated, the first dose should be given as soon as possible, ideally within 24 hours and no later than 72 hours. Contact a provider or emergency department; availability at urgent-care and sexual-health clinics varies.[1][2]
The 72-hour window
CDC is unambiguous: PEP is medicine that prevents HIV after a possible exposure, PEP is for emergency situations only, and PEP must be started within 72 hours (3 days) after a recent possible exposure to HIV. The sooner you start, the better — every hour counts.[1]
Federal guidance narrows the target further. CDC's 2025 recommendations direct health care professionals to ensure the first dose is provided as soon as possible, and ideally within 24 hours, but no later than 72 hours after exposure. Available clinical evidence suggests the shorter the time from exposure to initiation, the greater the likelihood of preventing HIV acquisition.[2]
Two operational details save time in a real emergency. The initial dose should not be delayed due to pending results of any laboratory-based testing, and the first dose should be administered as soon as possible during the initial encounter.[2] The guidance states plainly that exposure to HIV is a medical emergency.[2]
When you need it
CDC lists the situations where PEP may be needed: during sex — for example, if a condom broke — through sharing needles, syringes, or other equipment to inject drugs, or if you've been sexually assaulted.[1]
CDC recommends a 28-day course after a substantial-risk nonoccupational exposure within 72 hours when the source has HIV without sustained viral suppression, or suppression is unknown. If the source’s HIV status is unknown, the decision is made case by case. PEP is not recommended for exposures with no substantial HIV risk.[2]
After a workplace exposure, report it promptly through your workplace procedure and seek immediate clinical assessment. Treating clinicians can call NCCC at 844-275-6222 for PEP advice: weekdays 7 a.m.–5 p.m. Pacific and weekends 10 a.m.–2 p.m. Pacific, excluding holidays. Do not wait for a consultation callback before seeking local care.[8][1]
If a partner living with HIV is on treatment with a sustained undetectable viral load, that changes the calculus: CDC's evidence review found no risk of sexual transmission from people who get and keep an undetectable viral load.[3] Bring that information to the visit; it may mean PEP is not needed.
The 28-day course and what it involves
If you're prescribed PEP, you'll need to take it daily for 28 days.[1] Federal guidance confirms the recommended course is 28 days using a newer-generation three-drug antiretroviral regimen.[2]
On effectiveness, the guidance is honest about the evidence base: no randomized, placebo-controlled clinical trial of nPEP efficacy has been performed, and there are no FDA-approved medications specifically for nPEP. What the accumulated evidence does show is that nPEP, when used as currently recommended — a 72-hour initiation window, a 28-day duration, and a newer-generation three-drug regimen — is safe, generally well tolerated, and likely to reduce the risk for HIV acquisition. Available data indicate nPEP is highly effective when taken as prescribed.[2]
Modern PEP regimens are generally well tolerated. Take the full prescribed course and contact the prescriber promptly about missed doses or side effects rather than stopping on your own. Starting promptly and taking the medicines as prescribed improve protection, but PEP is not a guarantee and follow-up testing is still needed.[2]
If possible exposures are recurring, discuss PrEP. CDC recommends a planned transition from PEP to PrEP for people with ongoing exposure who want it, with HIV testing at completion of PEP and continued follow-up. There does not need to be a gap between the two, but the transition should be arranged with the prescriber.[2][4]
PEP medicines can suppress HIV and delay detection, so ordinary test-window estimates should not be used to decide when you are in the clear. CDC recommends follow-up with both a laboratory antigen/antibody test and an HIV nucleic acid test at 4–6 weeks and 12 weeks after exposure. The clinician may defer the earlier test in selected people who started within 24 hours, completed every dose and are not starting PrEP. Keep the final follow-up even if an earlier result is negative.[7]
Florida angle: where to go tonight
In Florida, seek urgent assessment from a health care provider or emergency department; urgent-care and county sexual-health clinics may also provide PEP, but hours and medication availability vary. The Florida Department of Health has a statewide PrEP and PEP resource page. Its HIV prevention page lists more than 1,600 registered testing sites, which should not be assumed to all prescribe or stock PEP. Do not delay urgent care while waiting for a routine clinic appointment.[1][5][6]
Related questions
What if it has been more than 72 hours?
Still seek prompt care. Evidence is insufficient for CDC to recommend starting nonoccupational PEP more than 72 hours after exposure; this is not proof of an exact biological cutoff. A clinician can assess the exposure, arrange baseline and follow-up HIV testing, evaluate other infections and discuss future prevention, including PrEP when appropriate.[2]
How much does PEP cost?
Costs, clinic hours and medication availability vary. Ask a provider or emergency department about urgent PEP assessment and assistance rather than delaying care to compare prices. A clinic or case manager may help with insurance or medication-assistance programs; no particular clinic’s supply or coverage can be guaranteed.[1][2][5]
Will PEP make me sick?
Modern three-drug PEP regimens are generally well tolerated. Nausea, fatigue or headache can occur, depending on the medicines. Tell the prescriber promptly about side effects or missed doses. Taking the prescribed course matters, but protection also depends on factors such as prompt initiation, and follow-up testing is essential.[2]
Related from RiseUpToHIV
References & Sources
- CDC — Preventing HIV with PEP. States PEP must start within 72 hours, every hour counts, is taken daily for 28 days, lists qualifying exposures, workplace guidance and the PEPline number, and directs people to providers, emergency rooms, or urgent care. ↩ ↩ ↩ ↩ ↩ ↩ ↩
- CDC MMWR — Antiretroviral Postexposure Prophylaxis After Sexual, Injection Drug Use, or Other Nonoccupational Exposure to HIV. Directs first dose ideally within 24 hours and no later than 72 hours, no delay for labs, states HIV exposure is a medical emergency, defines the 28-day three-drug course, and describes the efficacy evidence base. ↩ ↩ ↩ ↩ ↩ ↩ ↩ ↩ ↩ ↩ ↩ ↩ ↩
- CDC — HIV Treatment as Prevention. States studies have shown no risk of sexual transmission from people who get and keep an undetectable viral load. ↩
- CDC — Preventing HIV with PrEP. States PrEP can help protect people who have been prescribed PEP and report continued risk behavior or have used multiple courses of PEP. ↩ ↩
- Florida Department of Health — PrEP and PEP. State resource page for PrEP and PEP services and materials in Florida. ↩ ↩
- Florida Department of Health — HIV Prevention. States Florida has over 1,600 publicly funded and registered HIV testing sites statewide. ↩
- CDC MMWR — Nonoccupational PEP recommendations (2025), laboratory testing and follow-up. HIV antigen/antibody plus NAT at 4–6 and 12 weeks after exposure; ARVs can delay detection. Source. ↩
- NCCC — PEP consultations for clinicians: 844-275-6222, weekdays 7 a.m.–5 p.m. Pacific and weekends 10 a.m.–2 p.m. Pacific, excluding holidays. Source. Checked September 21, 2026. ↩
Community publications like POZ, Positively Aware, and TheBody inform framing and lived-experience context on RiseUpToHIV. Every clinical, epidemiological, or public-health claim above is anchored to a primary source.