Cold sores, also commonly referred to as fever blisters, are fluid-filled lesions that most commonly develop on or directly around the lips. Cold sores are caused by an infection with the herpes simplex 1 virus. According to the American Social Health Association, 50 to 80 percent of adults carry the herpes simplex 1 virus. Cold sores are classified based on five stages through which they go.
Tingling Stage
The initial stage of a cold sore is called the tingling stage or prodrome stage. During this stage, a small area of skin will become swollen and red. The area begins to tingle and may become sore. During the tingling stage, the lesion cannot yet be seen. This stage lasts from one to two days.
Blister Stage
The blister stage occurs when the cold sore actually forms on the surface of the skin and fluid-filled blister becomes visible. There may be a single, large blister or a cluster of smaller blisters grouped together in a smaller area, according to The Patient Education Institute by MedlinePlus. This stage usually lasts two days.
Weeping Stage
The weeping stage, which may also be referred to as the ulcer stage, lasts only one day. This stage is characterized by the breakage of visible blisters. When the blisters break open, the fluid inside of them leaks out and oozes from the cold sore. According to the Patient Education Institute, this is the most contagious stage of cold sore classification because the liquid contained inside the blister contains millions of small herpes viruses.
Scabbing Stage
The scabbing stage is the beginning of the healing process of a cold sore. During the scabbing stage, the broken blisters will begin to form scabs that cover the open sore. In most cases, the initial scab will break open and bleed, triggering another smaller scab to form. This process is repeated until the cold sore disappears from the face. The scabbing stage generally lasts a minimum of two days.
Healing Stage
After the scabs from the scabbing stage have completely fallen off, a small reddish pink area will be left on the face in place of the sore. The cold sore is in the healing stage until the pink area has completely cleared and the skin has returned to normal color. MayoClinic.com notes that most cold sores will completely heal with no leftover visible marks or permanent scarring.
