Can you tell if you have or been exsposed to an std/sti with in 12 hours? if so which one(s)

Too soon: Gonorrhea and chlamydia testing is valid after 4-5 days, but no sooner. Blood tests for syphilis, HIV, etc take a few weeks. Be on the alert for symptoms like discharge from the penis, painful urination, or genital sores, which can show up any time from 2 days to a couple of weeks. Get checked ASAP if symptoms appear, otherwise best to wait a few days.

Don't bet on it: If you suspect you have been exposed pay attention and get checked out with any change in your system or at least every 6 mo.Viral illnesses like herpes and HIV take time to set up in your system and 12 hrs is too soon for them to show their presence, or generate any positive tests.Chlamydia & gonorrhea may produce no symptoms but should turn tests positive within the first week.