A cold sore is a skin infection caused by the herpes virus. It appears as an inflamed area on or near the lips, usually with one or more small blisters. Cold sores may cause itching or burning sensations. After a few days, the blisters dry out and form a scab, which indicates that the skin underneath is beginning to heal.
Once a person is infected with the herpes virus, it remains in the body permanently. Cold sores are transmitted through direct skin contact, such as hugging or kissing. The virus can become active again and lead to a new outbreak when the immune system is weakened, during periods of stress, or after exposure to excessive sunlight. Cold sores also tend to flare up around the time of menstrual cycles. During an active cold sore, the virus is contagious, and touching the blisters can spread the infection to other parts of the body or to other people.
To prevent the spread of cold sores, avoid touching the affected area. Protecting the lips from bright sunlight can also help reduce outbreaks. There are several treatments available that can help prevent or reduce the severity of cold sores.