STD Testing After Possible Exposure: Timing and Panels (2026)
After a possible STI exposure, knowing when to test is as important as knowing where. Testing too early — before an infection is detectable — can produce a false negative and false reassurance. This guide covers the window period for each major STI, which tests to order after a specific exposure, and where to find the most affordable options for targeted post-exposure testing.
Key takeaways
- Testing too soon after exposure can produce false negatives — each infection has a minimum window period before reliable detection.
- For HIV: the 4th-generation test is reliable after ~18–45 days. A negative at 90 days is considered conclusive.
- For chlamydia and gonorrhea: wait at least 1–2 weeks before testing.
- For targeted post-exposure testing (not broad screening), individual tests are often more appropriate and cost-effective than a full panel.
Window periods by infection
A window period is the time between exposure and when a test can reliably detect an infection. Testing within the window period may give a false negative even if infection has occurred.
| Infection | Window period (earliest reliable detection) | Conclusive at | Test type |
|---|---|---|---|
| HIV (4th gen, antigen/antibody) | 18–45 days | 90 days | Blood (antigen/antibody) |
| Chlamydia | 1–2 weeks | 2–4 weeks | Urine or swab (NAAT) |
| Gonorrhea | 1–2 weeks | 2 weeks | Urine or swab (NAAT) |
| Syphilis (RPR) | 3–6 weeks | 3 months | Blood |
| Herpes HSV-2 (IgG) | 12–16 weeks | 16 weeks | Blood (IgG antibody) |
| Hepatitis C | 8–11 weeks (antibody); 1–2 weeks (RNA) | 6 months (antibody) | Blood |
| Hepatitis B | 1–9 weeks (antigen) | 6 months (full panel) | Blood |
Window periods are approximate ranges based on currently available assays. Confirm specific window periods with the lab assay used. Source: CDC STI screening guidance.
Which tests to order after exposure
The appropriate tests depend on the type of exposure and your concern:
- Unprotected vaginal or anal sex (unknown partner status): Consider HIV, chlamydia, gonorrhea, and syphilis at minimum. If hepatitis B immunity is unknown, a Hep B surface antigen test is appropriate. Add herpes IgG if concerned, but note the long window period.
- Unprotected oral sex: Gonorrhea and chlamydia are transmissible this way (throat swab may be needed — confirm with the collection site). Syphilis and HIV risk is lower but present. Targeted testing based on the specific exposure is more appropriate than a comprehensive panel.
- Known HIV-positive partner: Contact a healthcare provider immediately if the exposure was recent (within 72 hours) — post-exposure prophylaxis (PEP) may be appropriate. Do not rely on a portal test as the primary response to a high-risk HIV exposure.
- Routine screening (no specific exposure): A comprehensive panel is appropriate. See the STD Testing hub for panel recommendations.
According to the CDC, STI screening recommendations are based on risk factors rather than a one-size-fits-all approach — targeted testing aligned with your exposure is often more informative and cost-effective.
Post-exposure test prices
For targeted post-exposure testing, individual tests or small bundles are often more appropriate than a comprehensive panel. Current lowest prices:
| Test | Best value | Price | Fees note | What's included |
|---|---|---|---|---|
| HIV (4th Generation) | HealthLabs or Walk-In Lab | $49.00 | None stated | Detects both HIV antibodies and p24 antigen |
| Chlamydia & Gonorrhea (urine) | LabReqs or HealthLabs | $99.00 | None stated | Urine-based combined test |
| Syphilis RPR | LabReqs | $39.00 | None stated | Rapid Plasma Reagin with reflex to titer if positive |
| Herpes HSV 1/2 IgG | LabReqs | $59.99 | None stated | HerpesSelect IgG blood test for HSV-1 and HSV-2 |
| Chlamydia only (urine) | Jason Health | $58.00 | $18 fee included in price | Individual chlamydia NAAT |
| Jason Health 5-test STD panel | Jason Health | $108.00 | $18 fee included in price | Chlamydia/Gonorrhea RNA, Syphilis RPR, HIV-1/2 |
| HealthLabs 10-test comprehensive | HealthLabs | $139.00 | None stated | Ten most common sexually transmitted infections |
Prices from each provider's public website, May 2026. Confirm current pricing before ordering.
Honest verdict on value for post-exposure testing
Verdict
- For HIV alone: HealthLabs or Walk-In Lab at $49 — the most affordable 4th-gen HIV test. Test at 45 days post-exposure for a reliable result; retest at 90 days for conclusive.
- For chlamydia + gonorrhea: LabReqs or HealthLabs at $99 for the urine combo test. Test at 1–2 weeks post-exposure minimum.
- For a broader post-exposure panel: Jason Health's 5-test panel ($108, fee-inclusive) or HealthLabs' 10-test panel ($139) are the most cost-effective comprehensive options. Jason Health's panel covers HIV, chlamydia/gonorrhea, and syphilis in one order.
- Note: Testing too early gives meaningless results. Timing matters as much as test selection.
Related pages
- STD Testing hub: Panels, Prices, and What to Know
- STD Panel Cost Comparison (all portals)
- STD / STI Testing Basics Guide
- Lab Tests Without Insurance
- Full provider comparison
Frequently asked questions
When should I test for HIV after exposure?
For a 4th-generation (antigen/antibody) HIV test, the window period is approximately 18–45 days. Testing before 18 days has a high false-negative rate. The CDC considers a negative result at 45 days to be highly reliable, and a negative at 90 days conclusive for 4th-generation tests. If you believe you have had a high-risk HIV exposure within the last 72 hours, seek PEP (post-exposure prophylaxis) from a healthcare provider before relying on a test.
How soon can chlamydia be detected?
Chlamydia can typically be detected 1–2 weeks after exposure using a NAAT test. Testing before 1 week risks a false negative because bacterial load may not be sufficient for detection yet. Testing at 2–4 weeks after exposure provides a reliable result.
Is a herpes test accurate soon after exposure?
No. The herpes IgG antibody test has a long window period — typically 12–16 weeks after infection, and some people take up to 6 months to develop detectable IgG levels. If you test within a few weeks of a potential exposure and get a negative result, it should not be interpreted as conclusive. The IgG test is most useful for determining status when there is no recent known exposure concern.
Should I see a doctor or use an online portal after a possible STI exposure?
For high-risk exposures — particularly potential HIV exposure within 72 hours — seeing a healthcare provider immediately is the right first step, as PEP may be appropriate. For lower-risk situations or follow-up testing after the window period, online portal tests are a convenient and affordable option. Use both resources appropriately: a provider for urgent clinical decisions, and portal tests for routine screening and follow-up.
Sources
- CDC — HIV Testing — https://www.cdc.gov/hiv/testing/index.html
- CDC — STD Prevention Screening Recommendations — https://www.cdc.gov/std/prevention/screeningreccs.htm
- CDC — Herpes Testing — https://www.cdc.gov/herpes/testing/index.html
- CDC — Hepatitis C Diagnosis and Testing — https://www.cdc.gov/hepatitis-c/hcp/diagnosis-testing/index.html
- WHO — Sexually Transmitted Infections — https://www.who.int/news-room/fact-sheets/detail/sexually-transmitted-infections-(stis)
- MedlinePlus — STI Tests — https://medlineplus.gov/lab-tests/sexually-transmitted-infection-sti-tests/
- Provider pricing sourced from each provider's public website, May 2026: HealthLabs, Walk-In Lab, LabReqs, Jason Health.