Cold sore (fever blister) identification: Distinguishing oral herpes from other types of mouth sores.

Cold sores (fever blisters) are usually differentiated from other types of mouth sores by way of observing their appearance and location.

Where do cold sores usually form?

Cold sores are usually found either:

On or at the edge of a person's lip. On the facial skin near a person's mouth.

Each new cold sore breakout will typically form in essentially the same location as any previous cold sore outbreaks.

What do cold sores look like?

Cold sores usually run their course in 8 to 12 days, taking the following forms during the five stages outlined below:

Day 1-2 : The Tingle stage.  [The Prodrome Stage.] In most cases a person's first indication that a cold sore is developing is that they notice a sense of soreness, tautness, or swelling in the location where their cold sore will ultimately form. Sometimes this same area will become slightly reddened. Day 2-3 : The Blister stage. The first readily visible sign of cold sore formation is the appearance of several fluid filled blisters. Usually these blisters are very small (smaller in diameter than the thickness of a dime) and they usually form in a cluster that is no larger than about the size of a nickel. In some cases individual blisters coalesce with others so to form a single larger blister. Day 4 : The Weeping stage.  [The Ulcer Stage.] Cold sore blisters usually rupture soon after they have formed, resulting in a shallow reddish ulceration whose surface becomes gray. This ulcerative phase of cold sore formation can be its most painful stage. This is also the stage during which a cold sore is most contagious. Days 5 - 8 : The Crusting stage. In those facial areas where a cold sore lesion is not kept wet by moisture from the mouth the ulcer will become dry and scab over with a brownish crust. This scabbing formation is often accompanied by an itching or burning sensation. The scab itself will often crack or break, which in turn can cause bleeding. Days 9 - 12 : The Final Healing stage. As time progresses so will the cold sore's healing. Usually a series of scabs will form on the lesion, each one flaking off before it is replaced by a new one. Each new scab will be smaller than the previous one until finally the cold sore resolves itself fully, in most cases without scarring.

Are fever blisters painful?

Yes, cold sores typically are painful although the degree of discomfort they cause can vary greatly from person to person. Additionally, each individual stage of a cold sore's development will have associated with it its own degree of discomfort. Usually the Weeping stage is the most painful.

How contagious is oral herpes?

Yes. Since cold sores contain the herpes simplex virus, if these virus particles are transferred to others they too can become infected. One common route by which the herpes virus is transmitted to others is by way of direct skin-to-skin contact such as kissing someone or even just brushing against their lesion. Virus particles can also be transmitted to others by way of an intermediary object such as an eating utensil, cup, lipstick or lip balm applicator, toothbrush, or even a face towel.

Besides transmitting virus particles to other people it is also important to realize that you can transfer the herpes virus to other parts of your own body. The herpes simplex virus can cause herpetic whitlow, a painful infection of the fingers. A herpes virus infection of the eye can result in corneal blindness. [This is why you should always wash your hands after handling or applying medicine to cold sores.]

The most contagious phase of a cold sore's formation is when its blisters rupture (the Weeping stage). This is because the liquid contained in these blisters holds literally millions of herpes simplex virus particles.

As a cold sore continues to run its course the number of virus particles that are present in the lesion diminishes. Usually by the time a scab has formed (the Crusting stage) the number of virus particles has lessened dramatically. From a practical standpoint however, all phases of a cold sore do have at least some virus present and each phase, from the Tingle stage on to the completion of healing, should be considered to be contagious.