Cold sores, which often occur on the skin of upper and lower lips, are caused by herpes simplex virus. At first, it was a cluster of small blisters, which felt itchy and gradually merged into large blisters. After bursting, yellow water can overflow and scab slowly. It is easy to be infected with bacteria after rubbing and scratching with hands, and purulent secretion can be seen, with burning sensation and slight pain. Wash the local area with 3% medical hydrogen peroxide, and then apply acyclovir ointment three times a day. Niuhuang Jiedu tablets, vitamin C, drink plenty of water.
Don't scratch and rub with your hands.