Cold sores (fever blisters) - Stages / Signs & Symptoms / How to identify them. / Pictures.

Cold sores and fever blisters (yes, they're the same thing) can be distinguished from other types of mouth sores by way of evaluating:

  • A) The way the look as they go through their various stages.
  • B) The location in which they've formed.

(Scroll on down this page for pictures illustrating both.)


The appearance of a cold sore will change as it works its way through the five stages of formation outlined below. This process usually takes between 8 and 12 days.

See our "Where do cold sores form?"
graphic below for more pictures.

#1 The Tingle stage (Prodrome stage): Days 1 & 2.

In most cases, a person's first indication that they have a cold sore (fever blister) developing is that they notice a sense of soreness, tautness, or swelling in the area where it will ultimately form.

Appearance - A slight reddening of the area may occur.

#2 The Blister stage: Days 2 & 3.


Appearance - The blisters are usually very tiny (smaller across than the thickness of a dime) and form in a cluster that is no larger than about the size of a nickel.


#3 The Weeping stage (Ulcer stage): Day 4.

The blisters usually rupture soon after they've appeared, resulting in the formation of an ulceration.

Appearance - During this brief stage, the lesion starts off as a red, shallow ulcer whose surface then turns grey.

Notes - This phase of fever blister formation can be the most painful stage and the one during which it's most contagious.

#4 The Crusting stage: Days 5 through 8.


Appearance - The scabbing looks like a dark red or brownish crust. It often cracks or breaks, which results in bleeding.

Notes - The formation of the scab is often accompanied by an itching or burning sensation.

#5 The Final Healing stage: Days 9 through 12.

As time progresses so will the sore's healing.



The locations where cold sores form.

B) Where do cold sores form?

Cold sores typically form either:

  • On or at the edge of the lip.
  • On the face, near the mouth.

(See graphic above too.)

Future cold sores will typically form in essentially the same location as previous outbreaks. Here's why.

C) Are cold sores contagious?

Yes. Since cold sores contain the herpes simplex virus, if these virus particles are transferred to others they too can become infected.

How can the herpes virus be transmitted to others?

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 touching up against their lesion (like during a hug). 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.

Always wash your hands after treating your fever blisters.

You can even transfer the herpes virus to other parts of your own body.

Besides transmitting virus particles to other people, it's also important to understand that you can transfer the herpes virus to other parts of your own body.

Herpes simplex can cause herpetic whitlow, a painful infection of the fingers. A herpes 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.]

When are cold sores the most contagious?

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.

D) 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.

 All FYI's ► 
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