You may have recently had unprotected sex and are wondering when you should take your STI test. It is important to note that STIs are not detectable by even the most accurate laboratory tests immediately after exposure.
For the most accurate result, you need to wait a certain amount of time after exposure to an infection before taking a test. This period of time is called the window period.
This article is a helpful guide with advice on when you should take your STI test.
Alternatively, you can try our Window Period Calculator for a more tailored time frame on when to test.
Window Periods
A window period refers to the amount of time between exposure to an STI and when a test can accurately detect the infection.
Different STIs have different window periods. For example, gonorrhoea can be accurately detected just 2 weeks after exposure, while syphilis can take up to 12 weeks to show up on a test.
The window period is different from the incubation period. The incubation period considers the time it takes for symptoms to appear. For example, after exposure to an infection, a person may develop symptoms in just a few days, but a test may not be accurate until weeks or months after exposure.
STI Window Periods: When You Should Test
Chlamydia: It can take up to 2 weeks from the time of exposure for a chlamydia test to show a positive result. We recommend waiting 2 weeks from the time of exposure to test for chlamydia.
Gonorrhoea: It can take up to 2 weeks from the time of exposure for a gonorrhoea test to show a positive result. We recommend waiting 2 weeks from the time of exposure to test for gonorrhoea.
Trichomoniasis (Trichomonas vaginalis): It can take 2 to 4 weeks from the time of exposure for a trichomoniasis test to show a positive result. We recommend waiting 4 weeks from the time of exposure to test for trichomoniasis.
Mycoplasma genitalium: It can take up to 2 weeks from the time of exposure for a trichomoniasis test to show a positive result. We recommend waiting 2 weeks from the time of exposure to test for trichomoniasis.
Syphilis: It can take 3 - 12 weeks from the time of exposure for a syphilis test to show a positive result. If you took a syphilis test less than 12 weeks (3 months) after potential exposure, we recommend repeating this after 12 weeks (3 months) have passed.
Human Immunodeficiency Virus (HIV): HIV can take 10 - 45 days from the time of exposure to show up positive in tests. If you took a HIV test less than 45 days (6 weeks) after potential exposure, we recommend repeating this after 45 days (6 weeks) have passed.
Hepatitis B Virus (HBV): It can take 1 week to 6 months from the time of exposure for a hepatitis B virus test to show a positive result. If you took a hepatitis B test less than 6 months after potential exposure, we recommend repeating this after 6 months have passed.
Hepatitis C Virus (HBV): It can take 1 week to 6 months from the time of exposure for a Hepatitis C test to show a positive result. If you took a hepatitis C test less than 6 months after potential exposure, we recommend repeating this after 6 months have passed.
As with all infections, it's best to know sooner rather than later, and many tests will produce a positive result before the window period has passed. Therefore we recommend testing soon after potential exposure, with a repeat test after any window period has passed.
If you are worried you may have an infection, we recommend abstaining from sex until you have been tested (and treated if applicable) for all infections, outwith all window periods.
Still unsure on when to test? Try our Window Period Calculator for further guidance.
You should collect and post your samples on the same day. If possible, your samples should be collected and posted on a day they can be collected by Royal Mail - i.e, not a weekend or a bank holiday.