Cold sore? Transmission of herpes simplex virus

Dear Ask The Doctor: On this past Saturday I developed a cold sore on the side of my mouth, now mind you, I remember getting one at 10 and I wasnt sexually active.I thought it was a pimple and tried to pop it and broke the skin in the process and now it looks disgusting. I have been in a monogamous relationship with a man and when I developed this sore it was right after we slept together (Thursday 2 days later). He tells me he has never had an outbreak before and has gotten one right after we saw each other on Monday. I bought a pack of Zicam and he has something but I didnt know if this was the right treatment and if it can be transfered to his genitals?

Dear Jesselyn: The virus that causes cold sores is known as the herpes simplex virus (HSV). There are two types of HSV, type 1 and type 2. Cold sores are usually caused by type 1. The type 2 virus is the one that causes genital lesions and is transmitted sexually. Herpes simplex infections are contagious. The virus is spread from person to person by kissing or other close contact with sores or even from contact with apparently normal skin that is shedding the virus. Infected saliva is also a means of transmitting the virus. People are most contagious when they have active blister-like sores, and you can catch the virus if you come into direct contact with the cold sore blisters or the fluid inside them, which contains a high number of the viruses. This can easily happen through touching the hands of someone who has touched their blisters. Once the blisters have stopped oozing or have crusted over, the person is no longer contagious. Never touch active lesions in other people (through kissing or sex). When cold sores are active, wash your hands frequently to avoid passing the virus on to others. Once infected, the virus typically resides in a dormant state within the body's nerve cells. The body's immune system is normally able to keep the virus in its inactive state. When an infected person is exposed to a "trigger," or if the immune system is weakened, the virus quickly multiplies and produces sores usually on the lips. There is no known cure for cold sores. Most people don't need treatment, since cold sores go away on their own, but some medications may be helpful like an antiviral medication, ointment form or taken orally to reduce the severity and duration of the lesions.