Most of the time the outbreaks seem to have a life of their own and there is no one factor that appears to have initiated or caused the outbreak. There are a number of factors that are known to cause an outbreak of herpes labialis including :
- Emotional and physical stress may alter or lower the immune system allowing the virus to awaken or reactivate.
- Colds or other upper respiratory tract infection may also reactivate the virus. These cold sores are often called fever blisters.
- Sun (including tanning beds) or wind exposure without protection, especially on the lips, may reduce the immune activity in the skin leading to a recurrence of cold sores.
- Hormone changes such as those seen during menstruation
- Local trauma or injury to the skin around the lips including dry cracked lips and injury to the skin following cosmetic surgery, chemical peels or laser therapy
Sources www.coldsores.ca
