What is the difference between a cold sore, herpes, and a canker sore? If they are different can I give my canker sore to someone else during sexual activity?

Canker sores most often occur in the mouth, on the inside of the cheek, beneath the tongue, or anywhere on a mucus membrane. Dr. Polly Wheat, of Barnard Health Services, states that unfortunately "the cause of a canker sore is unknown; thus we can’t say much about transmission." Canker sores, which always occur inside the mouth, are not herpes. However, cold sores occur on the outside of the mouth and are Herpes (usually Herpes Simplex I). Herpes can be transmitted from the oral area to the genital area. This occurs most often through oral sex. Keep in mind however, that it can also be transmitted manually if one touches the cold sore and then touches the genital region. So if you have a cold sore on your lips, take precautions during sexual activity.