About 3 weeks ago I had a cold sore on my lip and had sex with my boyfriend. He gave me oral sex during that time. Today, my vulva is extremely itchy, red, and irritated. Could my fiancé have picked up my cold sore on his lips and infected me with it?

You will need to be examined by a qualified health care provider to see if you have a sexually transmitted infection or some other condition that is irritating you. But it is possible for infections to follow the route you describe. For example, although herpes virus-1 (HSV-1) is most commonly associated with cold sores around the mouth, it can infect the sex organs. And, while herpes virus 2 (HSV-2) is most commonly associated with infections of the sex organs, it can infect the mouth and throat.

During oral sex — anilingus (on an anus), cunnilingus (on a vulva), or fellatio (on a penis) — the HSV-1 or HSV-2 in a cold sore can be passed directly to the sex organs or anus. It is also possible for the fluid from the “weeping” sore to be passed from mouth to mouth and then to the sex organs where it can start an infection. That’s why it’s best for people with open herpes sores, oral or genital, to refrain from intimate contact with other people.

If you are diagnosed with herpes, it may be a good idea for your partner to be tested, too. There are medications available today that reduce the number and severity of outbreaks and also reduce the risk of one partner infecting the other.