what are cold sores from
A person doesn't need to have a cold to get a cold sore. Cold sores can be brought on by other infections, fever, stress, sunlight, cold weather, hormone changes in menstruation or pregnancy, tooth extractions, and certain foods and drugs. In a lot of people, the cause is unpredictable.
The herpes simplex type 1 virus (HSV-1) usually causes cold sores, and the herpes simplex type 2 virus (HSV-2) usually causes genital herpes. The actual sores are similar in appearance for both forms of the virus. Itâs also possible for HSV-1 to cause sores on the genitals and for HSV-2 to cause sores on the mouth.