What are the causes of a fever blister or cold sore?

Cold sores: Cold sores or fever blisters are a type of viral infection caused by the herpes simplex virus. The virus is transmitted by contact with an infected individual. Once the virus enters the skin and causes infection, it tends to stay and can cause recurrences, particularly when there is intense sun exposure, an illness like cold/flu, menstrual cycles, minor trauma to lips such as burns or scratches.

Skin contact: Herpes simplex or fever blisters are a viral infection transmitted by skin to skin contact with someone who has been infected with the herpes virus. Herpes can be transmitted by someone that does not have an active lesion at the time of contact so active lesions are not necessary to transmit the virus to someone else.

Virus: Cold sores are normally caused by herpes simplex i & most people have this virus living in the nerves of the mouth. Some rarely have outbreaks while others have them more frequently - usually when under stress. Your md or dentist can prescribe medication to help them resolve faster & reduce the outbreaks.