How to Read Your STI Test Results

What do 'reactive,' 'detected,' and 'non-reactive' mean?

Non-reactive / negative / not detected: The test did not find evidence of the infection being tested for. This is the reassuring result. Important caveat: a negative result is only as reliable as the *window period* — the time after exposure during which the test can reliably detect the infection. If you tested too soon after a possible exposure, a negative result may need to be confirmed with repeat testing [1, 2].

Reactive / positive / detected: The test found evidence of the infection, or found antibodies suggesting past or current infection. This does not always mean you are currently infected — some tests (especially for syphilis and herpes) can be reactive due to past infection, certain other medical conditions, or occasionally a false positive. A reactive result means confirmatory testing and a clinician conversation are needed before any conclusions are drawn 1Ref 1Workowski KA, Bachmann LH, Chan PA, Johnston CM, Muzny CA, Park I, Reno H, Zenilman JM, Bolan GA (2021).Sexually Transmitted Infections Treatment Guidelines, 2021.Result terminology (reactive, detected, indeterminate), test-specific interpretation for HIV, syphilis, gonorrhea/chlamydia, hepatitis C, and herpes, and confirmatory testing pathways.

Indeterminate / equivocal: The result fell in a gray zone — neither clearly positive nor clearly negative. This requires repeat testing or a different test type 1Ref 1Workowski KA, Bachmann LH, Chan PA, Johnston CM, Muzny CA, Park I, Reno H, Zenilman JM, Bolan GA (2021).Sexually Transmitted Infections Treatment Guidelines, 2021.Result terminology (reactive, detected, indeterminate), test-specific interpretation for HIV, syphilis, gonorrhea/chlamydia, hepatitis C, and herpes, and confirmatory testing pathways.

What do results mean for specific infections?

HIV: Most current tests report 'non-reactive' (reassuring) or 'reactive' (needs confirmation). A reactive result on a screening test is followed by a confirmatory test — a positive screen is not the same as a confirmed HIV diagnosis [1, 3].

Syphilis: Results often include an RPR with a titer (a number like 1:4 or 1:8) and a confirmatory test (TPPA or FTA-ABS). A positive RPR in someone previously treated for syphilis may reflect old infection, not new — your clinician interprets this in the context of your full history 4Ref 4Centers for Disease Control and Prevention (2021).Syphilis — STI Treatment Guidelines 2021 (Web Chapter).Syphilis RPR titer interpretation and distinction between active and prior treated infection.

Gonorrhea and chlamydia: Usually reported as 'detected' or 'not detected.' A detected result always prompts treatment 1Ref 1Workowski KA, Bachmann LH, Chan PA, Johnston CM, Muzny CA, Park I, Reno H, Zenilman JM, Bolan GA (2021).Sexually Transmitted Infections Treatment Guidelines, 2021.Result terminology (reactive, detected, indeterminate), test-specific interpretation for HIV, syphilis, gonorrhea/chlamydia, hepatitis C, and herpes, and confirmatory testing pathways.

Hepatitis C: An initial antibody test reported as 'reactive' or 'non-reactive.' A reactive antibody result requires a confirmatory RNA test to determine whether infection is active or has resolved 1Ref 1Workowski KA, Bachmann LH, Chan PA, Johnston CM, Muzny CA, Park I, Reno H, Zenilman JM, Bolan GA (2021).Sexually Transmitted Infections Treatment Guidelines, 2021.Result terminology (reactive, detected, indeterminate), test-specific interpretation for HIV, syphilis, gonorrhea/chlamydia, hepatitis C, and herpes, and confirmatory testing pathways.

Herpes (HSV): Blood test results include a numeric index value. Values in the low positive range have a meaningful chance of being false positives — your clinician will interpret these carefully and may recommend a more specific test to confirm 1Ref 1Workowski KA, Bachmann LH, Chan PA, Johnston CM, Muzny CA, Park I, Reno H, Zenilman JM, Bolan GA (2021).Sexually Transmitted Infections Treatment Guidelines, 2021.Result terminology (reactive, detected, indeterminate), test-specific interpretation for HIV, syphilis, gonorrhea/chlamydia, hepatitis C, and herpes, and confirmatory testing pathways.

What is the window period and why does it matter?

Every STI test has a window period — the time after a potential exposure during which the test may not yet be able to detect the infection, even if one has occurred [1, 2].

• HIV: most current combination tests can detect infection within a matter of weeks; testing at 45 and 90 days after a potential exposure is often recommended for full certainty 3Ref 3US Preventive Services Task Force; Owens DK, Davidson KW, Krist AH, et al. (2019).Screening for HIV Infection: US Preventive Services Task Force Recommendation Statement.HIV screening test interpretation and the need for confirmatory testing after a reactive HIV screening result
• Gonorrhea and chlamydia: generally detectable within one to two weeks of infection
• Herpes: antibodies can take weeks to months to appear after infection
• Hepatitis C: antibodies typically become detectable within about two months

If you tested soon after a possible exposure, a negative result should be confirmed at the right interval — ask your clinician when to retest.

What happens after an abnormal result?

An abnormal result starts a clinical process — it does not end one. Your clinician will typically:

• Confirm the result with a second test, especially for HIV and syphilis
• Review your history and symptoms in context
• Discuss treatment if the infection is confirmed
• Support you in notifying partners who may need testing
• Schedule follow-up to confirm treatment worked 1Ref 1Workowski KA, Bachmann LH, Chan PA, Johnston CM, Muzny CA, Park I, Reno H, Zenilman JM, Bolan GA (2021).Sexually Transmitted Infections Treatment Guidelines, 2021.Result terminology (reactive, detected, indeterminate), test-specific interpretation for HIV, syphilis, gonorrhea/chlamydia, hepatitis C, and herpes, and confirmatory testing pathways

Partner notification can feel daunting. Clinicians and public health departments can help with this process confidentially.

What if you received results with no explanation?

If you got your results through a patient portal, a direct lab notification, or an at-home kit and no one has called to explain an abnormal result, contact the ordering clinic. A positive or reactive result that has not been followed up may simply mean your provider has not yet reviewed it in their workflow — do not assume it was seen if you have not heard from anyone. You have every right to call and ask 2Ref 2National Library of Medicine (2023).Sexually Transmitted Infection (STI) Tests: MedlinePlus Medical Test.Window period concept and guidance on following up when results are received without clinical explanation.