Cold sores are highly contagious. They are caused by the herpes virus that, like any other virus, is passed easily from person to person. One out of every eight people is thought to be infected with the herpes virus and most of these infections occurred early in life. Once the herpes virus is contracted it stays in the body for life as there is no known cure. Someone who is infected with the virus can spread it to others throughout his entire life. So when are cold sores contagious?
They are most contagious when there is an active lesion that is in the weeping stage. The fluid that seeps from a fever blister is teeming with the herpes virus. To curb the spread of the virus it is very important to wash your hands often if you have a cold sore. Not only can you spread the virus to other people but you can spread the virus around to other parts of your own body if for example you touch your cold sore and then rub your eyes or touch your genitals. Since fever blisters often tingle, it is a natural reaction to reach up and brush them or scratch them and when you do, the virus is on your fingers ready to be transmitted on whatever you touch next.
The lesion is contagious during all stages of its eruption, which can last up to 21 days. They usually start with a tingling sensation for a couple of days followed by a small bump that blooms into a weeping lesion that scabs over and slowly shrinks away. At any point, the fever blister is contagious. If a friend or family member has a cold sore it is important to avoid kissing them or sharing personal products like razors or toothbrushes.
Unfortunately, there are other times when cold sores are contagious. The virus can also be spread for a week or two before an outbreak and a week or two after an outbreak. It is also possible that the virus is shedding and is contagious when there is no outbreak at all. During these times, it is impossible to know that you are contagious.
Once a person becomes infected with the cold sore virus, it never goes away. Between outbreaks the virus retreats into the body along the nerves and lies dormant until something triggers it to begin reproducing. When this reproduction is underway, the virus spills into the bodily fluids. This is called virus shedding. At this point, there is no outward indication of viral activity but it is possible to spread the virus to others even though you have no symptoms.
For those reasons, the cold sore virus is easily spread among family members and others with close personal contact. That is why the majority of people harbor the herpes virus. Some may not even know they have it since the initial outbreak may mimic a mild flu and not even produce a cold sore. Some people with the cold sore virus have many outbreaks each year and others rarely have them. Certain triggers, which vary from person to person, seem to set them off. Sun exposure, stress, and eating certain foods are common triggers.
So, when are cold sores contagious? We know for certain they are contagious anytime there is a lesion visible upon the face and it is possible they are still contagious for up to two weeks after they have healed. We also know that a person who has had at least one fever blister sore will be able to spread the virus for the rest of his life and sometimes he will do so when he has no lesion apparent.