The testing for any STD must be done within the correct testing period. All infections, STD included, have a so-called ‘incubation period’. During this period, identifying the infection may be difficult. The test may show a false negative result during the incubation period.
STI testing table below provides information on what is the optimal time to get tested after exposure to STI / STD.

The testing window for common STIs is as follows:

Type of STI Pathogen type Testing window Type of test When to retest after treatment
HIV virus 10–33 days for a nucleic acid test.
18–45 days for an antigen/antibody test.
23–90 days for an antibody test
Blood or saliva test. Blood nucleic acid test gives earliest results None
Chlamydia bacteria 1–2 weeks Blood or urine sample, or swab of the throat, rectum, cervix, or vagina 3 months
Trichomonas protozoa (parasite) 1 week to 1 month Swab of rectum, penis, or vagina 2 weeks
Syphilis bacteria Within 3 weeks after sores appear. Sores appear usually 1 week after exposure Blood test 6 and 12 months
Gonorrhea bacteria 5 days to 2 weeks Blood or urine test. Swab of the anus, urethra, cervix, or throat Test 2 weeks after treatment, or 2 weeks later after exposure if the first test is negative
Herpes virus 1–4 months Blood test or swab of a sore None
HPV virus 3 weeks to a few months Pap smear in females only — no approved test for males None
Hepatitis virus 3–6 weeks for hepatitis B. 2–6 weeks for hepatitis C Blood test Retest 6 months later