The "window period" is the time between when you're exposed to an infection and when a test can reliably detect it. If you test during this window, you might get a negative result even if you're actually infected — a false negative.
Timing your test correctly is one of the most important things you can do to get accurate results. Here's the window period for every major STD.
Window period reference table
| STD | Test type | Window period | When to test |
|---|---|---|---|
| Chlamydia | NAAT (nucleic acid) | 1–5 days | At least 5 days after exposure for best accuracy. Can be detected very early. |
| Gonorrhea | NAAT (nucleic acid) | 1–5 days | At least 5 days after exposure. Similar detection window to chlamydia. |
| Syphilis | RPR / antibody | 3–6 weeks | Wait at least 3 weeks. Retest at 6 weeks for confirmation if initial test is negative. |
| HIV (RNA test) | RNA / NAT (early detection) | 9–11 days | Earliest possible detection. Only available through STDcheck (FDA-approved). |
| HIV (antibody) | 4th gen antigen/antibody | 18–45 days | Most standard tests. Wait at least 3 weeks, confirm at 3 months. |
| Herpes (HSV-1 & HSV-2) | IgG antibody (blood) | 2–12 weeks | Wait at least 2 weeks for initial screening. Most reliable after 12 weeks. |
| Hepatitis A | IgM antibody | 2–7 weeks | Test 2+ weeks after exposure. IgM antibodies appear early in infection. |
| Hepatitis B | HBsAg (surface antigen) | 3–6 weeks | Wait at least 3 weeks. Retest at 6 weeks if negative. |
| Hepatitis C | Antibody test | 8–11 weeks | Wait at least 8 weeks for reliable results. Some tests detect earlier. |
| Trichomoniasis | NAAT / wet mount | 5–28 days | Test at least 1 week after exposure for best results. |
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Compare your testing options
Now that you know when to test, the next step is choosing how. We compared the top at-home and lab-based testing services for 2026 — pricing, speed, accuracy, and what's included.
Compare testing options →The general rule: test at 3 weeks, confirm at 3 months
If you've had a potential exposure and aren't sure which STDs to worry about, most doctors recommend testing at 3 weeks after exposure for an initial screening, then retesting at 3 months to confirm. This catches most infections within their reliable detection window.
This is the same recommendation STDcheck's physician team makes — and it makes sense because different infections become detectable at different times. A 3-week test will catch chlamydia, gonorrhea, and early syphilis. A 3-month follow-up confirms HIV, herpes, and hepatitis results.
What is a false negative?
A false negative means the test says you don't have an infection when you actually do. This happens when your body hasn't yet produced enough antibodies (or the pathogen hasn't replicated enough) for the test to detect.
False negatives are the main reason window periods matter. The tests themselves are highly accurate — when used at the right time. CLIA-certified labs using FDA-approved tests achieve 95–99% accuracy when the window period has passed.
What about HIV early detection?
Standard HIV tests look for antibodies, which can take 3–12 weeks to develop. But STDcheck offers the only FDA-approved HIV RNA test, which looks for the virus's genetic material directly. This can detect HIV as early as 9–11 days after exposure — weeks before antibody tests become reliable.
If early detection matters to you (for example, after a high-risk encounter), this is the fastest way to get a reliable answer.
Need the earliest possible HIV detection?
STDcheck's FDA-approved HIV RNA test
Detects HIV as early as 9–11 days after exposure — weeks before standard antibody tests. This is the only FDA-approved HIV RNA test available through an online testing service.
Get the HIV RNA early detection test →How often should you test?
The CDC recommends:
- All sexually active adults: At least once a year for common STDs.
- Multiple or new partners: Every 3–6 months.
- Men who have sex with men: Every 3–6 months for syphilis, chlamydia, gonorrhea, and HIV.
- Pregnant women: Early in pregnancy for syphilis, HIV, and hepatitis B. Chlamydia and gonorrhea if at risk.
- After any potential exposure: Test at the appropriate window period for the specific STD.
Regular testing is normal and responsible. Millions of people do it every year — it's just part of taking care of yourself.
Key takeaway
Timing matters. The best testing approach is to test at 3 weeks after exposure for an initial screen, then retest at 3 months for a definitive answer. This catches the vast majority of infections within their reliable detection windows.
Disclaimer: This article is for informational purposes only. Window periods can vary based on individual factors. Always consult a healthcare provider for personalized medical advice.