Are cold sores caused by the same virus that causes colds?
Cold sores are caused by the herpes simplex virus, not by one of the over 200 viruses that leads to colds. People infected with herpes simplex tend to have flare-ups when their immunity is lowered such as during illness or stress. Not infrequently, the herpes infection will cause a mouth sore during or after a bad cold or flu hence the association and the name.
