STD Window Periods by Infection (Chart)
Quick answer
A window period is the time between an exposure and the point when a test can reliably find the infection. CDC gives figures for HIV (about 10 to 90 days, depending on the test), hepatitis C (antibodies about 8 to 11 weeks) and herpes blood tests (repeat at 12 weeks). For chlamydia, gonorrhea, trich and syphilis CDC gives no single window, and the NHS says up to 7 weeks. If you may have been exposed to HIV in the last 72 hours, don't wait for a test: go to urgent care or an ER now and ask about PEP.
Your testing days
Chlamydia: NAATRetest if negative before day 49
HIV: Antigen/antibody lab testReliable by day 45
Syphilis: Blood testsRetest if negative before day 49
Too earlyMay detect; retest if negativeReliable
Counted from your most recent exposure. CDC gives no single window for chlamydia, gonorrhea, trich or syphilis; the cautious date uses the NHS "up to 7 weeks". Work out your own dates
Possible HIV exposure in the last 72 hours? Do not wait for a test. PEP is an emergency treatment and CDC says it must be started within 72 hours. Go to urgent care or an emergency room now and ask for PEP.
A window period is the time after an exposure when a test may still come back negative even though an infection is there. It is not a sign that the test failed. It means there isn’t yet enough virus, bacteria or antibody to detect. Where CDC gives a figure, it is shown below. Where it doesn’t, we say so and use the NHS’s cautious guidance instead.
What are the window periods for each STD?
| Infection | Test | When it can usually detect it | Source |
|---|---|---|---|
| HIV | NAT (tests for the virus) | 10 to 33 days | CDC |
| HIV | Antigen/antibody lab test (blood from a vein) | 18 to 45 days | CDC |
| HIV | Rapid antigen/antibody test (finger stick) | 18 to 90 days | CDC |
| HIV | Antibody tests and self-tests | 23 to 90 days | CDC |
| Hepatitis C | RNA test (tests for the virus) | As early as 1 to 2 weeks | CDC |
| Hepatitis C | Antibody test | Usually 8 to 11 weeks | CDC |
| Hepatitis B | Triple panel (blood) | No set CDC window. Average incubation is 60 days (range 40 to 90). Ask a clinician. | CDC |
| Herpes | Type-specific blood test | Repeat 12 weeks after the presumed exposure | CDC |
| Herpes | Swab of a sore (NAAT) | Most sensitive while a sore is present (CDC) | CDC |
| Chlamydia | NAAT (urine or swab) | No single CDC window. Up to 7 weeks for STIs in general. | NHS |
| Gonorrhea | NAAT (urine or swab) | No single CDC window. Up to 7 weeks for STIs in general. | NHS |
| Trichomoniasis | NAAT | No single CDC window. Up to 7 weeks for STIs in general. | NHS |
| Syphilis | Blood tests | No single CDC window. Up to 7 weeks for STIs in general. | NHS |
If you have symptoms, test now rather than waiting for the window to pass. If your result is negative and your exposure was recent, repeat the test after the window.
Why does HIV have so many windows?
Different HIV tests look for different things. A NAT looks for the virus itself, so CDC says it can detect HIV sooner than other tests. Antigen/antibody tests look for a viral protein and for antibodies. Antibody tests, which include most rapid and home self-tests, look only for your body’s response and take the longest.
CDC also says a positive antibody test needs a follow-up test to confirm it. If you take a test inside its window and it’s negative, CDC says to test again after the window has passed.
What about hepatitis B and C?
For hepatitis C, the RNA test can find the virus before antibodies appear. CDC says RNA testing is recommended for anyone who might have been exposed in the past 6 months, even if the antibody test is negative. Antibodies usually take 8 to 11 weeks to appear.
For hepatitis B, CDC doesn’t give a single post-exposure window. It gives an average incubation period of 60 days (range 40 to 90 days). Ask a clinician when to test and whether to repeat. If you know you were exposed to hepatitis B, contact a clinician promptly, because preventive treatment is time-sensitive.
What about chlamydia, gonorrhea, trich and syphilis?
CDC’s treatment guidelines for these infections don’t give one waiting time after exposure. The NHS says STIs can take up to 7 weeks to show on a test, and that with no symptoms it’s best to wait that long. If you test earlier, a clinician may suggest repeating the test.
For people who have been treated, CDC says to retest approximately 3 months after treatment for chlamydia and gonorrhea, and to be tested again about 3 months after treatment for trich. For chlamydia, CDC says a NAAT done less than 4 weeks after finishing treatment isn’t recommended.
What about HPV?
There is no window period to look up for men, because the CDC says there is no test to find out a person’s HPV status and tests aren’t recommended for men. See is there an HPV test for men.
How do I work out my own dates?
Count from the date of your most recent exposure. If you have had more than one since your last test, count from the latest. The window-period calculator on this site does the date math for you, and a clinician can pick the test that fits your timing.
Get care now if
- You may have been exposed to HIV in the last 72 hours. Go to an ER or urgent care now and ask for PEP.
- You were sexually assaulted. Seek urgent care promptly and ask about PEP.
- A fever, new rash or sores after a possible exposure
- Severe pelvic, lower belly or testicular pain
Call 911 for a medical emergency. Otherwise, an urgent care clinic, sexual health clinic or your doctor can see you.
When to test
- Within 72 hours of a possible HIV exposureSeek care now and ask about PEP. CDC says it must be started within 72 hours. A test is not a reason to delay.
- Any time you have symptomsGet tested rather than waiting out a window period. A clinician may repeat the test later.
- About 6 to 7 weeks after an exposureCovers the NHS 7-week guidance for most STIs, and the longest lab-based HIV window (45 days) for an antigen/antibody blood test.
- About 3 months after an exposureCovers the longest HIV windows (90 days), the 12-week herpes blood test repeat, and the hepatitis C antibody window.
Common questions
What is a window period?
It is the gap between an exposure and the time a test can reliably show the infection. CDC defines it for HIV as the time between exposure and when a test can detect HIV in your body. A negative result during the window doesn't rule out infection.
If I test negative inside the window, what should I do?
Test again after the window has passed. CDC says to get tested again after the window period for the test you took.
Why do the windows differ so much between tests?
Different tests look for different things. A NAT looks for the virus itself and can detect HIV sooner than other tests, while antibody tests look for your body's response and take longer.
Do windows change if I'm treated or on PEP?
PEP changes the follow-up schedule. CDC says follow-up HIV testing is at 4 to 6 weeks and 12 weeks for people taking it. Ask the clinician who prescribes it to confirm your dates.
Next: match the test to what happened.
The test finder suggests tests and dates in under a minute. Nothing you enter is stored.
Sources
- CDC, Getting Tested for HIV
- CDC, Clinical Guidance for PEP
- CDC, Hepatitis C: Clinical Screening and Diagnosis
- CDC, Hepatitis C: Clinical Overview
- CDC, Hepatitis B: Clinical Overview
- CDC, STI Treatment Guidelines, 2021: Genital Herpes
- CDC, STI Treatment Guidelines, 2021: Chlamydial Infections
- CDC, STI Treatment Guidelines, 2021: Gonococcal Infections in Adolescents and Adults
- CDC, About Trichomoniasis
- NHS, Sexually transmitted infections (STIs)
This guide is general information written by a patient advocate using public health sources. It is not a diagnosis. Only a clinician or a lab test can tell you whether you have an infection. Read how we write and check our guides.