How Long After Sex Should You Get Tested for STDs?

Possible HIV exposure in the last 72 hours? Don’t wait to test. Post-exposure prophylaxis (PEP) is an emergency treatment that must be started within 72 hours. Go to urgent care or an emergency room now and ask for PEP. Test later.

There is no single waiting time that works for every STD. A test can only find an infection once there is enough of the germ, or enough of your body’s response to it, to detect. That gap is the window period, and it differs by infection and by test type.

How long after unprotected sex should I get tested?

The honest answer is “twice, if you want to be sure”: once soon, and once after the longest relevant window has passed. Here is how the main windows look, using CDC figures where CDC gives them.

• HIV. CDC says a NAT can usually detect HIV 10 to 33 days after exposure, a lab blood test for antigens and antibodies 18 to 45 days, a finger-prick antigen/antibody test 18 to 90 days, and antibody tests (including home self-tests) 23 to 90 days.
• Herpes blood test. CDC says repeat type-specific testing 12 weeks after the presumed time of exposure is indicated, because an earlier test can be falsely negative.
• Hepatitis C. CDC says antibodies usually take 8 to 11 weeks to become detectable, and an RNA test can find the virus as early as 1 to 2 weeks after exposure.
• Chlamydia, gonorrhea, trichomoniasis and syphilis. CDC does not publish one waiting time for these. The NHS says STIs can take up to 7 weeks to show on a test, and advises waiting that long if you have no symptoms. With symptoms, test now.

When in doubt, use the longer window. The full chart is on the window periods by infection page.

What should I do in the first 72 hours?

If the sex was with a partner who has HIV or whose status you don’t know, HIV is the time-sensitive risk. CDC says PEP is for emergencies and must be started within 72 hours, and its clinical guidance says to start as soon as possible, ideally within 24 hours. A clinician decides whether PEP makes sense for your exposure.

Pregnancy is also time-sensitive if you could become pregnant. Emergency contraception is time-limited too. Women’s Health (a US government site) says some pills work within three days of sex and others within five, so ask a pharmacist or clinician promptly. It does not protect against STIs.

Should I test now or wait?

Do both, if you can:

1. Test now if you have symptoms, or want to know where you stand. A result now mostly reflects older infections, not this exposure.
2. Test again after the window passes. CDC says that after a possible HIV exposure, a negative result should be followed by another test once the window period for that test has passed.

If you are on PEP, CDC says follow-up HIV testing is at 4 to 6 weeks and 12 weeks.

What if I tested negative too early?

A negative inside the window isn’t a clearance. It means nothing was found yet. Repeat the test after the window for that infection. If you can’t tell which window applies, choose the later one, and ask a clinician if you are unsure.

Which test should I ask for?

For most exposures a mix works: a urine or swab test for chlamydia and gonorrhea, blood tests for HIV, syphilis and hepatitis, and a swab for any throat or rectal exposure. If you are unsure, the test finder on this site helps you pick, and a clinician can tailor it to your sex and the body sites involved.

Where can I get tested?

A clinic, urgent care, doctor’s office or health department can all test. The CDC’s GetTested site finds free or low-cost, confidential options. You can also order online and visit a partner lab, which is covered on our other pages. Whichever route you take, tell them the date of the exposure so they can pick the right test.