Despite the name, a cold is not what causes cold sores, but a virus infection, called herpes simplex virus type 1 (HSV-1) is to blame. Cold sores usually are transmitted via well-meaning kisses and most already pick it up as a kid.
When someone gets infected with HSV-1, the virus makes its way through the skin and into a group of nerve cells (ganglion). The virus moves in here, takes a long snooze, and every now and then decides to wake up and cause a cold sore. Between outbreaks, HSV-1 hides inside nerve cells, so it's never completely cured.
Not everyone, who gets the herpes simplex virus develops cold sores. In some people, the virus stays dormant (asleep) permanently.
Cold sores generally signal their arrival with a warning period of red, irritated skin. The virus damages your skin as it reproduces. That leaves behind weepy sores that last about a week.
Cold sores usually appear on your lip. Blisters form, burst, and then crust over before they heal. From the time your skin turns itchy or red, the virus is likely present and you can spread it.
You're most contagious when blisters show up and just after they burst. Once your skin is completely healed and looks normal again, you can't spread it that way. But some people can pass the virus through their saliva at any time -- even if they never show the sign of cold sores.
The virus is usually present on an infected person's lip, even if there's no obvious sore. Because the virus often lives in saliva, you can also spread it if you share eating utensils or drinking glasses.
Use caution while you have a sore or are around someone with a cold sore. Don't kiss, drink from the same cup or eat from the same spoon before washing them.
Don't share toothbrushes, lip balm or or lipstick with someone.
Skip oral sex to avoid genital herpes.
Try to wash your hands often.
That will reduce most spread of HSV-1, although you may not be able to control the spread completely. What about a cold sore that isn't on your lip?
They aren't as common, but they can pop up anywhere on your face, like your cheek, chin, or nose. Most people's cold sores reappear in the same area each time.
It can sometimes spread to other parts of the body, when you touch a cold sore, then touch an area of broken skin or a mucous membrane (mouth, nose, genitals), which can lead to a herpes skin infection.
To prevent this, don't pick, pinch, squeeze or even touch the cold sore. If you do touch an active cold sore, don't touch other parts of your body but wash your hands as soon as possible.
Be especially careful not to touch your eyes. If HSV-1 gets into the eyes, it can cause a lot of damage. In fact, infection of the eyes by HSV-1 is the leading infectious cause of corneal blindness.
Cold sores can be dangerous for people whose immune systems are weakened (such as infants and people, who have cancer or HIV/AIDS) as well as those with eczema.
For people with any of these conditions, an infection triggered by a cold sore can be life threatening.
Babies can also get the herpes virus during a vaginal birth if their mother has genital herpes. You can't transmit the virus to your baby by breastfeeding though, even if you have an active cold sore.
It's very unusual for a child to get a cold sore in the first six months, because the antibodies received from their mother offers some protection. But if your baby is younger than 3 months and gets any kind of mouth sore, call the doctor right away.
In young babies, the herpes virus can spread to the brain and other organs, causing serious, potentially permanent or fatal damage.
If your child has a cold sore: wash their hands, try to keep them from picking when they sleep by putting mittens on at night and don't let them share toys, drinks or eating utensils nor kiss other children or babies.
Exposure to sunlight can trigger an outbreak, so sun protection is a good idea.
The take away message is: don't kiss newborns, babies, toddlers, children on the lips ever as you may pass a virus that has no cure. Just smile at them and play peekaboo!