A cold sore is a blister caused by the Herpes Simplex Virus (HSV-1) that forms along the mouth, particularly on the lips. The blistering is the active phase of the reproductive cycle of HSV. The HSV microbe can survive in two forms: awake and active or hidden and lying dormant in the nerve. HSV generally spends most of its time in the dormant or sleeping state. When the microbe becomes active, it travels through the nerve to the skin and produce a cold sore. This sore appears and heals in a series of six phases, according to the pharmaceutical company Novartis.
Tingling
The tingling phase of a cold sore is also known as the prodrome phase. The tingling can also be perceived as an itching or burning pain and is also commonly described as a feeling of rawness. These sensations occur as a result of the virus moving from the ganglion or sensory nerve root toward the nerve ending at the intersection of the skin. These sensations can last for one or two days, according to a National Institutes of Health (NIH) reference summary on cold sores. The prodromal symptoms are important to recognize because this is stage where prevention of a full outbreak can occur.
Redness and Swelling
Inflammation is a healthy reaction of the immune system that can occur for a variety of reasons, including infection. There are four cardinal signs of inflammation: redness, swelling, pain or itching and compromised function. A discussion of cold sores by BoardCertified.com, a website established for information on board certified physicians, notes that localized redness and swelling follow the prodromal phase and signify the inflammatory response to the virus multiplying within the skin cells.
Blistering
The blistering of a cold sore is regarded as the “outbreak” stage. During this stage, the virus multiplies and makes its way to the skin, causing an outbreak of small, fluid-filled blisters that occur on the raised and reddened portion of the skin, according to the Novartis website. The virus is actively replicating during the blistering phase, and it is highly contagious. Physical contact with this area should be avoided.
Weeping
The weeping phase of a cold sore is the most painful. Weeping is defined as the sluggish flow or oozing of liquid, according to the Merriam-Webster Online Dictionary. The pain during this phase results from the bursting of the small blisters, which can lead to a shallow ulcer says Novartis. The weeping may result in a yellowish crusting from the drying of the fluid coming out of the blister.
Scabbing
The body heals cold sores similarly to any injury or opening of the skin. A scab develops to cover an injury on the skin like a natural band-aid. First, the body deposits fibrous tissue in the area. Special clot-forming blood cells, other immune cells, and some dried blood become caught in the fibrin network. When they dry up, a scab develops. Novartis notes that this is usually the most embarrassing phase of the cold sore because of its unsightly look.
Healing
After ten to 14 days, a cold sore enters its last phase: healing. New tissue begins to proliferate beneath the scab and causes the scab to flake off within a couple of days. The healing phase of a cold sore should not cause scarring, notes the Mayo Clinic health library. The bright, new, flesh-colored skin will appear where the scab once was. The full cycle of the outbreak ends with the herpes virus going back into its dormant or sleeping state.
