What causes cold sores?

Anyone who has had cold sores knows the feeling: a tingling, burning sensation in the lips, a sure signal that a little bump underneath the surface will emerge as an ugly painful red blister that is impossible to hide. If you plaster it with make-up, it often gets worse and there is nothing you can do about it for the next week or two. A few days later, the blister bursts, clear fluid is released and a scab forms.

The herpes simplex virus, generally the strain called HSV-1, is the culprit that causes outbreaks of cold sores. The liquid that comes from the blister when it breaks open is the source of infection and it can be spread through saliva, shared utensils or direct contact. The virus can also be sexually transmitted and can cause genital herpes, as well. The herpes simplex virus lies dormant in the nerve cells until activated. For people who are infected with the virus and suffer from cold sores, this may happen several times a year. The virus can be activated by several conditions; stress, for instance, is a known trigger for cold sores. Cold sores are also called fever blisters, and an illness with fever can cause an outbreak. Hormonal changes in women may cause a cold sore to emerge, as well as fatigue, overexposure to sunlight and even food allergies. Irritation to the mouth, such as dental work, can also trigger a cold sore.


Some of the conditions that are known cold sores triggers can be avoided. People who know that they are infected with the virus and have a tendency to develop cold sores can try stress management, apply sunscreen to the lips, and get enough sleep. If a cold sore develops, you should try to relieve the discomfort and avoid passing it on to others.