 [ Symptoms ] how long after sexual intercourse will one know if they have herpes my fiance just found out she has herpes how long after sexual encounter will you know if you have it how long does it take to after having sex with someone [ Disease ] most helpful answer how long before you know if you have been infected with genital herpes possibly never many people like your fiancee have no idea they are infected with genital herpes that is how it gets spread and men like yourself often have few symptoms if you do get symptoms you will likely notice small blisters on your penis or scrotum these eventually will burst and crust over before disappearing however it is possibly you will never notice them because you know your fiancee positively has herpes you should see your doctor for a blood test to determine whether or not you also have the virus if you do not have the virus and do not want to contract it then you should use a condom it does not provide 100 protection against getting herpes but it is a good start to increase your chances of avoiding the virus do not have sex when your fiancee is having an active outbreak of sores i am sorry to hear your fiancee just learned she has herpes just fyi there is no cure for this yet i wish you both the best