Since so many people in winter seem to contract cold sores and the associated fever blisters, one would think that we are infected  just like we catch a cold from other sufferers and germs in our surroundingsThe question thus arises whether cold sores are really contagious, or is it just a coincidence that a lot of people get them at the same time of year, when conditions are similar?The answer is that it depends on the cycle of the infection.The cold sores can be transmitted under optimum circumstances for a short while only.So generally Are Cold Sores Contagious is more a question of when rather than if.