Oral herpes is a very common type of infection that is caused by the herpes simplex virus. Many "cold sores" that people get from time to time are caused by one of the herpes viruses. The herpes simplex virus as two different types. Herpes simplex virus type 1 is the type that usually causes infections of the mouth (like cold sores) and herpes simplex virus type 2 is the type that usually causes the sexually transmitted disease. About 10% of the cold sores are caused by herpes simplex type 2 and about 10% of the genital herpes infections are caused by herpes simplex type 1. Thus, for the most part type 1 is associated with the cold sores and type 2 is associated with the genital infection. This means that almost certainly your cold sores are caused by the herpes virus that typically does not cause the sexually transmitted disease. When you do have an open cold sore, there is a very small (theoretical) risk that you could pass this on to someone during oral sex, though we usually don't worry
about this possibility (because it is so small)
I suggest that you schedule an appointment with your primary care physician
when you get one of these sores. He or she can provide you with guidance on how to prevent them from occurring and treat them when they do occur.