
A cold sore is contagious during the prodromal period and when a sore is visible, but herpes viruses can be spread even when there are no symptoms or sores. If you get cold sores, it is very important to wash your hands often and keep your hands away from your face. Transmission Herpes viruses are spread by touch. They break and ooze a clear fluid, form a painful sore, and then form a crust or a scab. Not everyone who gets cold sores will notice symptoms during the prodromal period. You can transmit the viruses at this time even though sores aren't yet visible. You may run a low fever (less than 100.5 degrees F or 38 degrees C).

There is no cure for the virus that causes cold sores. Cold sores can be triggered by stress, illness, exposure to the sun or wind, menstrual periods, dental treatment, or other events, but not every outbreak can be associated with a specific trigger. Oral herpes (cold sores, fever blisters) and genital herpes are both caused by viruses in the herpes family. Cold sores are highly contagious and very common. Cold sores, also known as fever blisters or oral herpes, appear on the lips, on the gums, or in the mouth.
