STD Window Period Chart — When To Test After Exposure
Updated: Nov 05, 2025 • Clear guidance on earliest reliable testing and recommended follow-up.
Quick overview
This chart summarises typical detection windows and recommended test types for common sexually transmitted infections. Use it to plan initial and follow-up testing after a potential exposure. If in doubt, contact our clinicians for personalised advice.
Window period chart — detection & recommended tests
| Infection | Earliest detectable | Typical reliable window | Best test type | Notes / follow-up |
|---|---|---|---|---|
| HIV (RNA) | ~7–10 days | ≥10–14 days (RNA), 14–28 days (4th-gen for many cases) | HIV RNA (PCR/NAT) or 4th-generation (Ag+Ab) | RNA detects earliest; confirm reactive with follow-up tests. Final reassurance at 12 weeks per guidelines. |
| HIV (Antibody / 4th gen) | ~14 days (4th gen may detect some earlier) | ≥3–4 weeks reliable; repeat at 12 weeks for full certainty | 4th-generation/ELISA and confirmatory assays | Use RNA if exposure <3 weeks; 4th-gen suitable after 2–4 weeks. |
| Syphilis (VDRL / TPHA) | ~3–6 weeks | 3–6 weeks post-exposure typical | VDRL (screen) + TPHA (confirm) | If tested earlier and negative, repeat at 6–12 weeks if concern persists. |
| Gonorrhea & Chlamydia (NAAT) | ~5–7 days (site dependent) | 1–2 weeks reliable | NAAT (urine or swab: urethral, vaginal, rectal, pharyngeal) | Test site selection depends on exposure (oral/anal/genital). |
| Herpes Simplex Virus (lesion swab) | Immediate if lesion present | Lesion PCR positive at presentation | PCR or lesion swab; IgG serology later | Serology (IgG) may take weeks (4–12 weeks) to appear after infection. |
| Hepatitis B (HBsAg) | ~4 weeks (varies) | 4–12 weeks typical | HBsAg (antigen) and anti-HBc | Vaccination status affects interpretation; follow-up testing may be needed. |
| Hepatitis C (HCV RNA / Ab) | RNA ~1–2 weeks; antibodies ~8–11 weeks | RNA early detection; Ab reliable at ~3 months | HCV RNA (PCR) for early; anti-HCV for later | Use RNA if early diagnosis needed (e.g., recent high-risk exposure). |
| HPV (screening) | DNA tests detect infection from exposure, but timing varies | Variable — not typically used for immediate post-exposure testing | HPV DNA (cervical swab), routine screening | HPV is usually assessed as part of routine screening rather than immediate exposure testing. |
Key takeaways: early detection choices depend on test type — NAT/PCR detects genetic material earliest, antigen/4th-gen tests detect earlier than antibodies, and antibody tests often require weeks to months. When in doubt, book a clinician consultation for personalised timing.
Practical testing plan after a possible exposure
- Day 0–3: baseline tests (and for HIV within 72 hours consider PEP — see clinician immediately).
- Day 7–14: consider HIV RNA (PCR) if very recent exposure; NAAT for gonorrhea/chlamydia at 1–2 weeks.
- Week 3–4: 4th-generation HIV (Ag/Ab) test; syphilis testing can start around 3–6 weeks.
- Week 12: final HIV antibody/confirmatory testing for full reassurance per many guidelines.
Note: timing and exact tests depend on exposure type and symptoms — always confirm with a clinician.
Need personalised advice or testing now?
Message us on WhatsApp for a quick triage — we'll recommend which tests and when to repeat them based on your exposure.
Get clinician advice — WhatsAppCommon FAQs
If my first test is negative, do I need repeat tests?
Yes — negative results during the window period may be false. Follow the recommended schedule above or your clinician's advice for repeat testing.
Can you do multiple tests in one visit?
Yes — we can collect multiple samples (blood, urine, swabs) in a single clinic or mobile visit. We'll confirm total price and any home-visit fee when booking.