YES! Cold sores ARE herpes. They are caused in 95% of cases by the herpes virus hsv-1. The other 5% are caused by hsv-2.
I caught genital herpes from receiving oral sex from my boyfriend, who gets cold sores. He didn't have one at the time, and hadn't had one for six months. We thought it was safe when he didnt have one, although we knew when he did have a cold sore he could give me genital herpes.
Lots of people think you aren't infectious when you don't have a cold sore, or 'it isn't the same kind of herpes and you can't transfer it down there'.
Unfortunately, they're all WRONG. You can often be infectious when you have NO cold sore - the virus is still in your system. You are actually infectious about 10% of the time when you have absolutely no cold sore at all.
Receiving oral sex from someone with oral herpes (cold sores) is becoming a VERY common way to catch genital herpes. In fact it is responsible for over half of all new genital herpes cases - 50-60% of new genital herpes infections are caused by the 'oral' herpes virus hsv-1.
I know three other women with genital herpes apart from myself, and all of us have genital hsv-1 caught from a partner that got cold sores giving us oral sex.
Chances of it happening...
8 out of 10 people get cold sores. So the chances of your partner having cold sores are pretty high. IF they do have oral herpes themselves, and have had it more than a few months (enough time to develop antibodies to the virus), it is extremely unlikely they would ever contract genital herpes form receiving oral sex from you. So if your partner has a history of cold sores chances are they are pretty safe.
If they DON'T have a history of cold sores, and don't have oral herpes, their chances are much higher. And I am talking about when you don't have any symptoms, not even a tingle, never mind when you have a cold sore! 70% of herpes infections are passed when no symptoms are present.
Of the girls I know that caught genital hsv-1 through oral sex, one caught it on a one night stand - she didn't even have intercourse with him, they just had oral sex. My sister caught it 3-4 months into a new relationship. I caught it seven years into my relationship with my boyfriend. None actually had a cold sore.
BUT... it took me a long time to catch it. Part of this is because we knew there was a risk so he hardly ever gave me oral sex. Part of it was because he was incredibly careful. If you avoid any time you think you might be getting a cold sore, the slightest tingle or itch, when you are run down or ill because the virus is more likely to be active, and for a good couple of weeks after a cold sore, it should help lower the risk.
Unfortunately, oral sex is never safe sex. You can always use a condom/dam.