Cold sores

Cold sores are caused by the herpes simplex virus. It usually occurs after a fever, infection, cold, or sun, wind, life tension, menstruation, lack of sleep, or when the immune system is suppressed. This disease is highly contagious. The incubation period is about 3-10 days. After the occurrence of cold sores, it may last for 3 weeks. If you have a tendency to be allergic, it is likely that your immune system is weak and you may be susceptible to cold sores.