I tested negative after 15 days—should I test again?« Back to Previous Page

Yes, you should repeat the test.

A negative HIV test at 15 days is encouraging, but it is not final. The final timing depends mainly on which test was done.

Simple rule:
4th generation HIV test (lab test): repeat at 45 days / 6 weeks for a conclusive result. CDC says lab-based antigen/antibody tests usually detect HIV within 18 to 45 days after exposure.

3rd generation / rapid / self / antibody-only test: repeat at 90 days / 3 months for a conclusive result. CDC says antibody tests usually detect HIV within 23 to 90 days, and NACO guidance has long used the practical cutoff of up to 3 months for antibody-based testing.

Important exceptions:
If you took PEP or are on PrEP: the testing plan can change, because antiretroviral medicines can affect or delay HIV test detectability. CDC advises follow-up HIV testing after PEP at 30 days and 90 days, and for people on PrEP, CDC recommends ongoing HIV testing with HIV antigen/antibody plus HIV-1 RNA testing during follow-up.

If you have symptoms such as fever, rash, sore throat, swollen lymph nodes, or other concerning symptoms after a recent exposure, do not wait for the final cutoff date—test as soon as possible and get medical advice. In such cases, an earlier doctor-guided test, sometimes including HIV RNA/NAT, may be needed. CDC notes that NAT can usually detect HIV in 10 to 33 days.

In a nutshell

“A negative test at 15 days is a good sign, but not conclusive. Repeat at 45 days if it was a 4th generation test, or at 90 days if it was a rapid/antibody test. If you took PEP/PrEP or have symptoms, testing may need to be done earlier and follow-up timing can change.”